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The potential for using cyanobacteria (blue-green algae) and algae in the biological control of plant pathogenic bacteria and fungi
Abstract
Cyanobacteria (blue-green algae) and eukaryote algae occur in freshwater, marine, and terrestrial (soil) habitats. In fact, these microorganisms comprise most of the world's biomass. Although the cyanobacteria are mostly photoautotrophic, some are facultative heterotrophs, capable of growing on certain substrates in darkness. Also, some are non-phototrophic and hence, are obligate heterotrophs. A number of cyanobacteria and eukaryote algae, particularly macroalgae, produce various, biologically active compounds. These include antibiotics which in laboratory tests inhibited bacteria and fungi that incite diseases of humans. In addition, the following fungi which are of interest to plant pathologists, were inhibitedin vitro by substances produced by various cyanobacteria: The saprophytesChaetomium globosum, Cunninghamella blakesleeana, andAspergillus oryzae and the plant pathogensRhizoctonia solani andSclerotinia sclerotiorum. Extracts from seaweeds (macroalgae) sprayed on plants have been reported to reduce the incidence ofBotrytis cinerea (gray mold) on strawberries,Erysiphe polygoni (powdery mildew) on turnips, and damping-off of tomato seedlings. Because many cyanobacteria and algae produce a large number of antibacterial and antifungal materials, are almost never a threat to the environment, and many can be grown in quantity in mass culture, they are suitable candidates for exploitation as biocontrol agents of plant pathogenic bacteria and fungi. Much additional work remains to be done however, to thoroughly evaluate cyanobacteria and algae and their products for this role.
... Cyanobacteria create a wide range of bioactive chemicals such as alkaloids, polyketides, amides, fatty acids, indoles, and lipopeptides with antibacterial, antifungal, antialgal, and antiviral properties by inhibiting growth, metabolic and physiological actions of the pathogens (Dahms et al. 2006;Pradhan et al. 2022a, b;Burja et al. 2001;Gerwick and Sparks 2014;Dayan et al. 2014;Duke 2018;Mohanty et al. 2020). Cyanobacteria cell constituents have been shown to reduce the incidence of Botrytis cinerea on strawberries, Erysiphe polygoni, which causes powdery mildew on turnips and damping off disease in tomato seedlings, as well as saprophytes like Chaetomium globosum, Cunninghamella blakesleeana, and Aspergillus oryzae, and plant pathogens like Rhizoctonia solani and Sclerotinia sclerotiorum (Kulik 1995). Several studies have found that compounds like Fischerellin from Fischerella muscicola have antifungal activity against a variety of plant pathogenic fungi, including Uromyces appendiculatus (brown rust), Erysiphe graminis (powdery mildew), Phytophthora infestans, and Pyricularia oryzae (rice blast), but less effective against Monilinia fructigena (brown rot and Pseudocercosporella herpotrichoides) (Hagmann and Jüttner 1996;Papke et al. 1997). ...
... It primarily affects compositae, particularly lettuce (Lactuca sativa L.) and other rosette plants (Tassara et al. 2008). Fungal plant diseases such as Sclerotium sclerotiorum (Cottony rot of vegetables and flowers) and Rhizoctonia solani were suppressed in vitro by extracts from N. muscorum (Kulik 1995). Nostoc sp., a known potential cryptophycin producer, is a source of natural insecticides against fungus, insects, and nematodes (Biondi et al. 2004). ...
... Cyanobacteria can help farmers to achieve long-term success in agriculture (Singh et al. 2017). Diazotrophs are Kulik 1995;Tassara et al. 2008 cyanobacteria that can be used to make inexpensive and environmentally beneficial biofertilizers via supplementation of nitrogen deficit, soil aeration, water holding capacity, and vitamin B12 to the plants (Song et al. 2005). In the rice crop cultivation area, the most efficient nitrogen-fixing cyanobacteria are Aulosira fertilisima, Anabaena variabilis, Calothrix sp., Tolypothrix sp., Nostoc linkia, and Scytonema sp. ...
Accelerating population growth and depletion of natural energy/resources pose threats to environment as well as to long-term food and energy supply. The use of chemical fertilizers pollutes water and cause soil-erosion, infertility and impose alarming danger to the health of both beneficial microorganism and human. There is need for finding sustainable alternative for biomass production in the anthropocene. Cyanobacteria, a diverse group of prokaryotes are the most successful, the oldest life form on the planet. They play an important role in maintaining and building up soil fertility, increasing plant growth and yield as a natural biofertilizer, nutrient cycling, phosphorus bioavailability, N2-fixation, environmental protection, and also disease prevention. Cyanobacteria convert radiative energy into chemical energy. These biological systems generate oxygen through photosynthesis. These organisms provide food, energy, secondary metabolites, cosmetics, and medications. These high-value products can be made from biomass of cyanobacteria through environment-friendly large-scale cultivation while lowering CO2 levels-a green technology. The biofertilizer of cyanobacterial origin could be the replacement of the chemical fertilizer. The methods of preparation and role of cyanobacterial as biofertilizers for sustainable agriculture are focused in this paper.
... Cell constituents of cyanobacteria are known to cut back the incidence of Erysiphe polygoni and Botrytis cinerea which are pathogenic and are responsible for causing diseases Complimentary Copy in plants. These also reduce the expansion of saprophytes like Chaetomium globosum, Aspergillus oryzae, and Cunninghamella blakesleeana, as well phytopathogens such as Sclerotinia sclerotiorum and Rhizoctonia solani (Kulik 1995). ...
... The fungus Sclerotinia sclerotiorum causes "white mold," one in every of the foremost polytheist plant pathogens, mostly affecting lettuce (Lactuca sativa L.) of Compositae and other species of rosette plants (Tassara et al. 2008). It is found that cell extracts of N. muscorum can inhibit the in vitro growth of several fungal phytopathogens such as Rhizoctonia solani which causes root and stem rots (Kulik 1995). It is estimated that Nostoc sp., produces a potential source of natural pesticides known as cryptophycin, which is pathogenic against certain fungi, insects, and nematodes (Biondi et al. 2004). ...
Cyanobacteria are the largest primitive group of Gram-negative, cosmopolitan, photoautotrophic prokaryotic microflora, which can thrive in marginal areas with a bare minimum requirement of light and nutrients. These are some of the potential organisms that are responsible for a major global evolutionary transformation ultimately resulting in the origin of aerobic metabolism.
In regards to the present challenges concerning agricultural ecosystem and depleting environmental standards, molecular and biotechnological advancements offer a more definitive approach to address food security for later generations and also to resolve the
complex problems of the environment. Certain specific features of cyanobacteria such as their ubiquitous presence, oxygenic photosynthesis, short generation time, rapid growth rate, high biomass yield, production of useful by-products, and biofuels, enhancement of
soil fertility and reduction of greenhouse gas emissions, collectively offered these bio-agents as a gem for sustainable development. Their aptitude to fix atmospheric N2 has rapidly increased their demands as bioinoculants for increasing soil fertility and improving environmental standards.
Genetically manipulated cyanobacteria can be designed with desired genes for the production of several targeted chemicals and bio-fuels such as bio-gas, bio-diesel, etc. resulting in a new pavement for the generation of biofuels that are economically befitted. This chapter is an attempt to assess the importance of ecological information for rational management and exploitation of these organisms and also to highlight the informative
data about the utilities of cyanobacteria and their magnificent roles implied in resolving the agro-ecological problems for the future welfare of human and the planet.
... Algae are one of the chief biological agents that have been studied for the control of plant pathogenic fungi, particularly for soil-borne diseases (Hewedy et al., 2000). Cyanobacteria (blue-green algae) and eukaryotic algae had been reported to produce biologically active compounds, that have antifungal activity (Kulik, 1995;Schlegel et al., 1998), antibiotic and toxic activity (Bonjouklian et al., 1991;Kiviranta et al., 1993). Moreover, Anabaena spp., Scytonema spp., and Nostoc spp. ...
... have been reported to be effi cient for controlling soilborne fungi causing damping-off disease as well as the growth of soil fungus Cunninghamella blakesleana (Frankmolle et al., 1992;Chetsumon et al., 1993). Also, Kulik (1995) reported that culture fi ltrates or cell extracts from cyanobacteria and algae applied to seeds protect them from damping-off fungi such as Fusarium sp., Pythium sp. and Rhizoctonia solani. Furthermore, El-Mougy and Abdel-Kader (2013) reported that commercial blue-green algae extracts, Weed-Max at 2g/l (extracts in powder phase), and Oligo-X at 2 ml/l (extracts in liquid phase) could suppress soil-borne fungi causing root rot of cucumber, cantaloupe, tomato, and pepper plants under plastic greenhouse conditions and enhance the antagonistic ability of bioagents, fungi, bacteria and yeast. ...
Efficiency of various organic acids, organic salts, essential oils, algae (an extract of Chlorella vulgaris and a commercial product), and bioagents against Magnaporthiopsis maydis , causing maize late wilt disease, was evaluated in laboratory and field conditions. For the in vitro tests, isolated M. maydis field strains from Egypt were used. Additionally, in field experiments different application methods were tested for their efficacy throughout two successive growing seasons. Results showed maximum growth inhibition of M. maydis at different concentrations of salicylic acid, ascorbic acid, benzoic acid and humic acid as well as sodium benzoate, potassium sorbate, di-potassim phosphate and calcium choloride, in descending order. The essential oils of carnation, lemongrass and black seed followed a similar trend. The minimum pathogenic fungal growth was achieved when the pathogen was exposed to the antagonistic Trichoderma viride followed by Trichoderma harzianum, Bacillus subtilis and Pseudomonas fluorescens treatments. Under field conditions, the highest disease reduction was recorded after treatment with salicylic acid (all application methods), humic acid (all application methods), sodium benzoate (seed dressing), carnation oil (seed dressing or seed dressing +foliar spray) and the bioagents B. subtilis and P. fluorescens (soil drench). Overall, all treatments and all application methods led to significant lower disease incidence compared to the untreated control in both growing seasons. Additionally, all treatments achieved an enhancement of plant morpho-genesis and yield characters. The most effective combinations of compounds/bioagents and application methods can be considered for future use in IPM management of late wilt disease of maize.
... Cyanobacteria produce a diverse array of bioactive metabolites that can inhibit fungal and bacterial phytopathogens [83]. Crude extracts prepared from cyanobacteria using various organic solvents have shown antifungal activity against Aspergillus, Fusarium, Sclerotinia, Rhizoctonia, Pythium and other pathogens [84]. ...
Abstract
Purpose: This paper reviews the diverse agricultural applications of cyanobacteria for improving soil health, plant growth, and agricultural sustainability.
Research Method: The paper provides a literature review summarizing recent research on cyanobacteria's roles in soil aggregation, biofertilization, abiotic/biotic stress tolerance, yield improvements, carbon sequestration, and bioremediation. Both laboratory studies and field trials evaluating cyanobacteria's effects on soil properties and plant growth are discussed.
Findings: Cyanobacteria can enhance soil structure, provide fixed nitrogen, mitigate salinity stress, increase crop yields, and sequester carbon. Their stress adaptations, antimicrobial metabolites, and synergies with plants and microbes underpin many benefits. However, translating laboratory research into effective field inoculants remains challenging.
Research Limitation: Variability in effectiveness across cyanobacterial strains, plant species, and environments limits current understanding. More field testing is needed along with assessment of potentially negative impacts.
Originality/Value: This review highlights promising areas for cyanobacteria to promote agricultural sustainability while identifying knowledge gaps in genetics, plant-microbe interactions, and soil ecology that require further study. It emphasizes the need for locally-adapted, integrated solutions leveraging cyanobacteria's multifunctional traits.
... The nitrogen-fixing potential of blue-green algae has also been proposed as a potentially beneficial resource for the production of food crops such as rice (Venkataraman 1979). Interestingly, it has also been suggested that cyanobacteria and microalgae might be utilized to provide beneficial biological control from pathogens of certain crops due to their antifungal and antibacterial and antiviral properties (Kulik 1995;Kreitlow et al. 1999;Mudimu et al. 2014;Prasanna et al. 2015). Although the uses of microalgae biomass for crop production may be more removed from direct utilization in pig production, these end products are worth considering as alternative exports from the system with potential economic returns to benefit the overall costs of production. ...
... Numerous researchers have examined their significance as nitrogen fixers in rice fields. Although most nitrogen-fixing cyanobacteria are likely hetero-cystous, there are certain non-heterocystous species that are capable of fixing nitrogen [11].Plants at a higher level are able to reabsorb the nitrogen that the algae fixed. The nitrogen-fixing capabilities of cyanobacterial species are well-documented, and their use in enhancing soil fertility for environmentally responsible rice farming is widely acknowledged. ...
As a vast and varied collection of microbes, algae are capable of photosynthesis, which allows them to convert energy from sunlight into chemical compounds. The agricultural sector relies heavily on algae due to their usefulness as biofertilizers and soil stabilizers. The use of algae, especially seaweeds, as fertilizers leads to a decrease in nitrogen and phosphorus discharge compared to that produced by animal dung. The water that eventually makes its way into rivers and seas is therefore of higher quality. As dietary supplements for humans, these creatures are farmed all over the globe. They need very little water to grow, and they may be cultivated on desert and abandoned land, producing food that is both clean and carbon neutral. Iodine is abundant in seaweeds. The dietary intake of the milking cow determines the milk's iodine content. If you want more iodine in your milk, feed your cows seaweed. Incorporating algae into chicken feed speeds up the egg- laying process. This article provided a concise overview of algae and its agricultural applications, covering the essentials for anyone involved in this field.
... It is noteworthy that some of the cyanobacterial strains were as effective as the fungicide, or even superior in increasing the surviving seedlings. These findings are in conformity with the findings of Kulik (1995); Ashour and Afify (1999); Afify and Ashour (2023) Who reported that when cyanobacterial isolates added to the seeds plant were protected from soil-borne fungi. The same conclusions previously mentioned regarding the effects of biocontrol agents on the surviving seedlings held true in case of their effects on dry weight and plant height (Table 3). ...
... Algae can be used as biocontrol agents with nematicidal effect, [96][97][98] where extracts and exudates of cyanobacteria have been reported to inhibit hatching and to cause immobility and mortality of juvenile plant parasitic nematodes in vitro. Antifungal and antibacterial activities were also studied where culture filtrate has hydrolytic activity againt phytopathogens [99][100][101] . The most economically important fungal pathogen is Fusarium sp., and other fungal pathogens have also controlled under above studied. ...
Population of the Earth has been projected to reach ~9.7 billion by 2050 and Asia and Africa would be the major contributors to this enhanced population. This increased population is directly related with higher demand of food security in very near future. Modern agricultural management is heavily dependent on the fertilizers for increased crop production, but increasing use of chemical-based and inorganic fertilizers may be a serious threat to the environment and human health. Microalgae have biostimulant and biofertilizer properties which are attracting the interest of farmers and agrochemical industries. Application of microbes such as cyanobacteria, microalgae, endo/ecto-mycorrhizal fungi, rhizobacteria, and others serves as an ecofriendly approach for sustainable agriculture practices. Biostimulants are the products derived from organic matter that are applied in small quantities and are able to stimulate the development and growth of several crops under stressed as well as optimal environmental conditions. Plant biostimulants encompass diverse organic and inorganic substances (humic acids and protein hydrolysates) as well as prokaryotes (plant growth promoting bacteria) and eukaryotes such as mycorrhiza and macroalgae (seaweed). Biofertilizers are products containing living microorganisms or natural substances that are able to improve chemical and biological soil properties,
stimulating plant growth, and restoring soil fertility. Microalgae and cyanobacteria (blue-green algae), are attracting interest from scientists, extension specialists, private industry and plant growers because of their versatile nature, simple unicellular structure, high photosynthetic efficiency, ability for heterotrophic growth, adaptability to domestic and industrial wastewater, amenability to metabolic engineering, and possibility to yield valuable co-products. This review article focuses on the research
achievements on cyanobacteria and microalgae based plant biofertilizers and biostimulants in the agricultural applications. The challenges to commercializing these kinds of biofertilizers are also
discussed.
... Fungi and bacteria are the chief biocontrol agents against plant pathogens particularly soilborne fungi. Although the use of cyanobacteria as biofertilizers is well known for a long time, recently, attention has been focused on the role of cyanobacterial secondary metabolites in phytopathogen control (Kulik, 1995) and their potential application in crop protection (Singh, 2014). The use of cyanobacterial inoculants as antagonists of phytopathogens provides a promising alternative to chemical fertilizers and pesticides which are detrimental for the health of environment. ...
Cyanobacteria, which are Gram-negative prokaryotic oxygenic photoautotrophs, have a remarkable history dating back to the Precambrian epoch, approximately 4.5 billion years ago. During this ancient period, they played a pivotal role in transforming Earth's environment from an anoxic (oxygen-deprived) state to an oxic (oxygen-rich) one. These cyanobacteria display a wide range of morphological and ecological diversity, making them adaptable to various environmental conditions and stress factors. Their cosmopolitan distribution further underscores their resilience and versatility. One of the key attributes of cyanobacteria is their unique ability to perform nitrogen fixation. This biological process enables them to convert atmospheric nitrogen into a usable form, which has proven to be beneficial in agriculture. Cyanobacteria have been successfully employed as bio-fertilizers, particularly in rice ecosystems. This application has the potential to address the increasing demand for sustainable agricultural practices. With the global population projected to surpass 9.1 billion by 2050, the pressure to develop alternative and sustainable agricultural processes becomes paramount. Cyanobacteria emerge as a highly promising resource in this context, offering a multifaceted approach to meet the needs of this growing population. Their utility extends beyond just agriculture. Cyanobacteria can be harnessed for various purposes, including as a source of food, feed, and raw materials for the pharmaceutical and biotech industries. Their versatility makes them a valuable asset in addressing the multifaceted challenges posed by a burgeoning global population.
... Aspergillus oryzae (Trichocomaceae) and plant pathogens such as Rhizoctonia solani (Ceratobasidiaceae) and Sclerotiana sclerotium (Sclerotiniaceae) [10]. Methanolic extracts of Nostoc commune FK-103 (Nostocaceae) and Oscillatoria tenuis FK-109 (Oscillatoriaceae) showed antifungal activities against Phytophthora capsici (Pythiaceae), an oomycete plant pathogen that causes blight and fruit rot of peppers and other important commercial crops. ...
Metal nanoparticles exhibit excellent antifungal abilities and are seen as a good substitute for controlling different kinds of fungi. Of all known taxa, cyanobacteria have received significant consideration as nanobiofactories, as a result of the cellular assimilation of heavy metals from the environment. The cellular bioactive enzymes, polysaccharides and pigments can be used as reducers and coatings during biosynthesis. The probability of the antifungal activity of selenium nanoparticles (SeNPs) to prevent plant fungi that can affect humans was evaluated and a toxic Iranian cyanobacterial strain of Desmonostoc alborizicum was used to study the biotechnology of SeNP synthesis for the first time. Characterization of nanoparticles with a UV-Vis spectrophotometer showed the formation of SeNPs in the range of 271–275 nm with the appearance of an orange color. Morphological examination of nanoparticles with Transmission Electron Microscopy (TEM), revealed the spherical shape of nanoparticles. The results of X-Ray Diffraction (XRD) showed 7 peaks and a hexagonal structure of average crystal size equal to 58.8 nm. The dispersion index of SeNPs was reported as 0.635, which indicated the homogeneity of the nanoparticle droplet size. The zeta potential of the nanoparticles was + 22.7. Fourier-transform infrared spectroscopy (FTIR) analysis exhibited a sharp and intense peak located at the wave number of 404 cm− 1, related to the SeNPs synthesized in this research. The results of the antifungal activity of SeNPs showed among the investigated fungi, Pythium ultimum had the highest resistance to SeNPs (14.66 ± 0.52 µg/ml), while Alternaria alternata showed the highest sensitivity (9.66 ± 0.51 µg/ml) (p < 0.05). To the best of our knowledge this is the first report concerning the characterization and antifungal screening of SeNPs biosynthesized by Iranian cyanobacteria, which could be used as effective candidates in medical applications.
... The growth improvement can be dependent on various aspects. In the case of nitrogen-fixing cyanobacterium, as per the report of Kulk (1995) and Adam (1999), the nitrogenase and nitrate reductase activities of algae associated with the plant surfaces could have induced the plant growth. ...
The capability of microalgae had been studied for a long time; however, some basics of using microalgae as a biostimulant are still in question. In the present work, experiments were conducted to reply to questions such as (a) how does the application time affect the effects of microalgae treatments and (b) does variety or genetic variation cause differences in the effect of microalgae biomass application on the plants? The different times of application had different weightage on different parameters; however, when applied at the early reproductive stage the yield as well as the nitrogen % in grain was significantly affected. As per the comparison, the result suggested that varietal differences had negligible differences in biological yield, hexose content, and total phenol content. Furthermore, microalgae biomass treatment irrespective of the strain species or genus influences the biological photosynthate accumulation and nitrogen uptake or in short, the efficiency of uptake. Finally, the metabolomic analyses suggested the influence of the microalgae strains on the biochemical composition of the plants.
... Extracts from seaweeds have also been shown to reduce plant diseases. Due to their ability to produce antibacterial and antifungal materials and their low environmental impact, cyanobacteria and algae show potential as biocontrol agents for plant diseases (Kulik, 1995). Ultimately, the sustainable cultivation of marine cyanobacteria for bioactive production requires a multifaceted approach that encompasses cultivation methods, selection, and genetic modification. ...
Marine cyanobacterial bioactives, due to their diverse chemistry and promising pharmacological properties, hold significant potential as therapeutic agents. Here, we comprehensively review the scientific state-of-the-art relating to marine cyanobacterial bioactives, including bioprospecting, preclinical and clinical studies, mechanisms of action, safety and toxicity considerations, sustainability, and conservation. We discuss challenges in and opportunities for developing marine cyanobacterial bioactives as therapeutics; we underscore their potential in treating life-threatening health ailments, such as cancer and neurodegenerative, inflammatory and viral diseases. We further articulate the significant potential of marine cyanobacterial bioactives for improving human health, and identify future research directions underpinning their development as therapeutics.
... Indole alkaloids such as the tjipanazoles isolated from Tolypothrix tjipanasensis are toxins produced by cyanobacteria. Therefore, they present interesting antifungal properties, in particular against phytopathogenic fungi causing plant infections (Bonjouklian et al. 1991;Kulik, 1995;Gademann and Portmann 2008;Walton and Berry 2016). ...
The space environment is extreme for plants growth and survival as gravity (gravitropism modification, water distribution), radiations (mutations enhancers), light spectrum regime and temperature are not optimal. Photosynthetic microorganisms are a foreseen solution for supporting plant development, growth, and stress tolerance in closed environments, like those designed for space colonisation. Indeed, photosynthetic microorganisms are known as secondary metabolites producers (exopolysaccharides, indole alkaloids, fertilisers) able to impact plant stimulation. Studying their abilities, application methodologies and best strains for space agriculture may lead to developing a sustainable and efficient approach for food production. Furthermore, as these microorganisms could also be used to produce oxygen and recycle waste materials increasing their interest in closed loop systems is undeniable. In this review we provide an overview of the current state of knowledge about existing biostimulants, their effects and applications, and the potential brought by photosynthetic microorganisms for life in closed environments.
Highlights Cyanobacteria's and microalgae's secondary metabolites can act as biostimulants for vascular plants when applied to the roots or the leaves.
Production of secondary metabolites in cyanobacteria can be enhanced in stressful environments.
Cyanobacteria can survive space-like stress by sur-producing secondary metabolites giving an advantage for space farming as a source of biostimulant compounds.
... (Bloor and England, 1989) are effective in suppressing damping-off and the growth of the soil fungus Cunninghamell ablakesleana. Particularly, seeds treated with cell extracts or culture filtrates from cyanobacteria are shielded from damping-off fungus such Fusarium sp., Pythium sp., and Rhizoctonia solani (Kulik, 1995). 29 of the 298 micro-algal strains evaluated in a previous study's antifungal activity was discovered, this study's focus was chosen because Nostoc communm FA-103 has a wide range of antifungal action against plant pathogenic fungi, particularly F. oxysporum (Kim, 2006). ...
... 작물생육을 촉진하거나 병원성 박테리아를 생물학적으로 제어하여 식물병에 저항성을 유도하는 등의 다양한 분야 에서 사용되어진다 (Kulik, 1995;Lee et al., 2016). ...
... Green algae are perhaps the most extravagant hotspot for some known and novel bioactive compounds with a great deal of differed pharmacological exercises, to be specific, anticoagulant, antithrombotic (Adhikari et al., 2006), antiviral, antitumor (Nishino et al., 1981), antioxidant, anti-inflammatory, antimicrobial, reducing blood lipids, therapeutic potential in surgery, immunomodulatory activity (Ahmad (Hassan, 2007). Kulik (1995) distributed a writing audit abridging the potential for utilizing cyanobacteria and green algae in the natural control of plant pathogenic microorganisms and parasites. Caire et al. (1997) announced that various centralizations of weaken fluid concentrate from nitrogen-fixing cyano-bacterium N. muscorum were effective in the control of a damping-off. ...
The potential wellspring of bioactive compounds from algae to upset the medicinal services has been well-promoted. The
bioactive substances produced by actively growing cells of algae includes proteins, fats, lipids, carbohydrates, phenol,
flavonoid, vitamins, free amino acids, enzymes, growth regulators, pigments, toxins and antibiotics. Truth be told a few items
created through some bioactive compounds in the green and blue green algae, these life forms are a rich wellspring of
fundamentally novel and organically dynamic metabolites such as antimicrobial, antiviral, antifungal, anti-allergic,
anticoagulant, anticancer, antifouling and antioxidant activities dressing. The utilization of bioactive compounds from algae
such as Chara in farming are announced as antimicrobial. Notwithstanding, the maximum capacity of bioactive compounds
in the agribusiness has still not been figured it out.
... Специфической антифунгальной активностью обладают многие биологически активные соединения, выделенные из цианобактерий, относящихся к родам Nostocales и Lyngbya (Kulik, 1995). Идентифицированы и запатентованы метаболиты цианобактерий, подавляющие развитие грибов -патогенов сельскохозяйственных культур (Prasanna et al., 2010). ...
Настоящий обзор посвящен цианобактериям и их метаболитам с полезными для человека свойствами. Метаболиты цианобактерий отличаются уникальным многообразием. Многие из них проявляют антибактериальную, антифунгальную, противоопухолевую, иммуносупрессивную и антиоксидантную активность. Обсуждаются проблемы и перспективы использования цианобактерий и биологически активных продуктов их метаболизма. Рассматриваются вопросы получения лекарственных препаратов и других ценных продуктов (пигментов, ферментов, аминокислот, витаминов, разлагаемого пластика), оценивается потенциал цианобактерий как источника биотоплива.
... Many biologically active compounds isolated from cyanobacteria of the genera Nostocales and Lyngbya have specific antifungal activity (Kulik, 1995). Metabolites of cyanobacteria that suppress the development of fungi that are pathogens of agricultural crops have been identified and patented (Prasanna et al., 2010). ...
This review focuses on cyanobacteria and their metabolites with beneficial properties for humans. Cyanobacteria metabolites are uniquely diverse. Many of them exhibit antibacterial, antifungal, anticarcinogenic, immunosuppressive, antioxidant activity, etc. The problems and prospects of using biologically active products of the cyanobacteria metabolism are discussed. The issues of obtaining pharmaceuticals and other valuable products (pigments, enzymes, amino acids, vitamins, and biodegradable plastic) are considered, and the potential of cyanobacteria as a source of biofuels is evaluated
... Recently, the biorefinery concept has been increasingly used to separate high-value products (nutraceuticals, food, and feed additives, cosmetics, pharmaceuticals) and low-value products such as biofuels, animal feed, and agricultural products (Moreno-Garcia et al. 2017;Arbib et al. 2022). During the last decade, numerous studies have been published focusing on the use of microalgae biomass in agricultural applications as biostimulants, biopesticides, and biofertilizers (Kulik 1995;Carneiro et al. 2021;García-González and Sommerfeld 2016;Grivalský et al. 2022;Ranglová et al. 2021;Ronga et al. 2019). When aimed at agriculture, the important point is the selection of suitable species and strains producing desired bioactive compounds (Ördög et al. 2004;Takács et al. 2019). ...
The microalga Chlamydopodium fusiforme MACC-430 was cultured in two types of outdoor pilot cultivation units—a thin-layer cascade (TLC) and a raceway pond (RWP) placed in a greenhouse. This case study aimed to test their potential suitability for cultivation scale-up to produce biomass for agriculture purposes (e.g., as biofertilizer or biostimulant). The culture response to the alteration of environmental conditions was evaluated in “exemplary” situations of good and bad weather conditions using several photosynthesis measuring techniques, namely oxygen production, and chlorophyll (Chl) fluorescence. Validation of their suitability for online monitoring in large-scale plants has been one of the objectives of the trials. Both techniques were found fast and robust reliable to monitor microalgae activity in large-scale cultivation units. In both bioreactors, Chlamydopodium cultures grew well in the semi-continuous regime using daily dilution (0.20—0.25 day⁻¹). The biomass productivity calculated per volume was significantly (about 5 times) higher in the RWPs compared to the TLCs. The measured photosynthesis variables showed that the build-up of dissolved oxygen concentration in the TLC was higher, up to 125–150% of saturation (%sat) as compared to the RWP (102–104%sat). As only ambient CO2 was available, its shortage was indicated by a pH increase due to photosynthetic activity in the thin-layer bioreactor at higher irradiance intensities. In this setup, the RWP was considered more suitable for scale-up due to higher areal productivity, lower construction and maintenance costs, the smaller land area required to maintain large culture volumes, as well as lower carbon depletion and dissolved oxygen build-up.
Key points
• Chlamydopodium was grown in both raceways and thin-layer cascades in pilot-scale.
• Various photosynthesis techniques were validated for growth monitoring.
• In general, raceway ponds were evaluated as more suitable for cultivation scale-up.
Graphical Abstract
... This influence can be, on one hand, positive, with several studies reporting that biomolecule-producing cyanobacteria promote germination, root length, shoot length, fresh weight, and dry weight, and other physiological parameters such as pigment content or phytohormone pool [29,31,32]. But on the other hand, some strains can release compounds with biocidal activity, such as certain polyketides, amides, alkaloids, fatty acids, indoles, and lipopeptides [33][34][35][36]. ...
The potential of some soil cyanobacteria to influence plant development through the release of biologically active substances has been extensively characterized. The use of cyanobacterial culture supernatants is among the strategies for this purpose, as they contain compounds that can influence plant development. However, there is little information on how the remaining nutrients from the culture medium used, could contribute to the effect observed in the treated plants. In the present work, Trichormus sp., a native Chilean cyanobacterium isolated from drylands whose supernatants improved the cumulative germination and the shoot and root growth of the native grass Polypogon australis, was selected. The observed effects were significant when compared with water as a control but did not significantly differ when the BG-11 nutrient medium was used as a control. The nutrient content of Trichormus sp. supernatants was characterized throughout the growth phases of the culture on BG-11 medium, showing an important decrease in P (100 %) and Mn (84 %) content after the late exponential phase. Based on these results, a P and Mn-free BG-11 medium (BG-11 M) was prepared. In a bioassay with P. australis, the BG-11 M effect was compared with Trichormus sp. supernatants, which contained 40 % of P and 46 % of Mn with respect to the original BG-11 medium. The results showed that the BG-11 M was less effective in promoting the shoot growth of P. australis than the supernatants, indicating that both elements, P and Mn, have a role in the development of P. australis. We emphasize the need to consider the composition of nutrients remaining on the culture medium when evaluating the effects of cyanobacterial cultures on plant growth and development.
... Increasing concentrations of glutamic acid, seaweed extract and selenium in the study were associated with the promotion. The effect of glutamic acid and seaweed extract on stimulating growth characters could be due to their essential actions on enhancing cell division and the biosynthesis of organic foods [27,28]. In this respect, selenium was able to promote plant growth and improve leaf area of Valencia orange and Zagloul date palms [19,20]. ...
This work was conducted through two successive seasons (2018 and 2019) on Grand Nain banana grown in a private orchard located at El-Kalubia Governorate, Egypt to evaluate seaweed extract, selenium and glutamic acid effects on vegetative growth, yield as well as physical and chemical properties of the fruits. Plants were sprayed four times (mid of April, May, June and July) with glutamic acid at 50 or 100 ppm, seaweed extract at 0.05 or 0.1% and selenium at 50 or 100 ppm, as a single or combined applications. Treatments were very effective in stimulating all vegetative growth parameters, bunch weight as well as physical and chemical fruit properties comparing with to the control treatment. A superior effect was obtained with the foliar spray of seaweed extract, followed by glutamic acid and selenium. Spraying banana plants four times with a mixture containing glutamic at 100 ppm + seaweed extract at 0.1%+ or selenium at 100 ppm recorded the best results with reference to vegetative growth, bunch weight and fruit properties.
... Algal extracts are known for their antimicrobial, nematocidal, herbicidal, and insecticidal/acaricidal properties against crop pathogens and can be used as biopesticides [11,12,13]. The word biopesticide refers to naturally occurring biochemical compounds such as exopolysaccharides, hydrophobic biomolecules, and hormones (14) that are commonly produced by various microorganisms like bacteria, fungi, virus and algae or by genetically modified plants with the genes from these microbes that are used to control pests in agricultural practices. ...
Agricultural crops have become more resistant to synthetic pesticides and pressure mounts regarding their effect on our health and the environment. When these compounds leach into the ground waters, they become direct sources of human health hazards. Also, agricultural runoffs can cause widespread damage to flora fauna and in general affect the food chain in an ecosystem. To combat these deleterious effects, the race is on to bring biopesticides to market that are safe, effective at scale, affordable and can ensure future food security. In this present scenario there is an urgent need to look for alternate sources of similar compounds to replace synthetic pesticides that are sustainable, ecofriendly, and easily available to be mass produced. In this effort microalgae may play a very significant role as they have the capacity to produce a wide array of bioactive compounds with pesticidal properties. As a part of their daily metabolic activities through different physiological pathways they are known to produce and release compounds with anti-bacterial, anti-fungal, anti-protozoal, pesticidal, insecticidal properties. Microalgae, especially the cyanobacteria have very fast growth rates and are potent sources of raw material for the generation of these compounds therefore considered significant while considering biopesticides to replace synthetic ones. This review explores the use of microalgae driven release of biochemicals and secondary metabolites produced by microalgae, or microalgal biomass, that can serve as future promising biopesticides to replace the agrochemicals used these days in agriculture.
... Biologically active compounds are obtained from cyanobacteria which exhibit antibacterial, antifungal, antialgal, and antiviral activities (Teuscher et al. 1992; (Kulik 1995). Fischerella muscicola produces Fischerellin having antifungal potential against Uromyces appendiculatus causing brown rust, and Erysiphe graminis causing powdery mildew. ...
... The results explained that spraying with cyanobacteria caused an improvement in pepper plant resistance against biotic stresses, including fungal pathogens [49]. Furthermore, antifungal activity of A. platensis [50], D. muscorum [51], and A. oryzae [18] against fungal pathogens were also reported. Reducing symptoms and severity of infection is one of the most important goals of using fungicides, whether chemical or biological [52]. ...
Research in plant pathology has increasingly focused on developing environmentally friendly, effective strategies for controlling plant diseases. Cyanobacteria, including Desmonostoc muscorum, Anabaena oryzae, and Arthrospiraplatensis, were applied to Capsicum annuum L. to induce immunity against Fusarium wilt. Soil irrigation and foliar shoots (FS) application were used in this investigation. The disease symptoms, disease index, osmotic contents, total phenol, Malondialdehyde (MDA), hydrogen peroxide (H2O2), antioxidant enzymes (activity and isozymes), endogenous hormone content, and response to stimulation of defense resistance in infected plants were assessed. Results demonstrated that using all cyanobacterial aqueous extracts significantly reduced the risk of infection with Fusarium oxysporum. One of the most effective ways to combat the disease was through foliar spraying with Arthrospira platensis, Desmonostoc muscorum, and Anabaena oryzae (which provided 95, 90, and 69% protection percent, respectively). All metabolic resistance indices increased significantly following the application of the cyanobacterial aqueous extracts. Growth, metabolic characteristics, and phenols increased due to the application of cyanobacteria. Polyphenol oxidase (PPO) and peroxidase (POD) expressions improved in response to cyanobacteria application. Furthermore, treatment by cyanobacteria enhanced salicylic acid (SA) and Indole-3-Acetic Acid (IAA) in the infected plants while decreasing Abscisic acid (ABA). The infected pepper plant recovered from Fusarium wilt because cyanobacterial extract contained many biologically active compounds. The application of cyanobacteria through foliar spraying seems to be an effective approach to relieve the toxic influences of F. oxysporum on infected pepper plants as green and alternative therapeutic nutrients of chemical fungicides.
... Biologically active compounds are obtained from cyanobacteria which exhibit antibacterial, antifungal, antialgal, and antiviral activities (Teuscher et al. 1992;Dahms et al. 2006 (Kulik 1995). Fischerella muscicola produces Fischerellin having antifungal potential against Uromyces appendiculatus causing brown rust, and Erysiphe graminis causing powdery mildew. ...
The importance of cyanobacteria has increased tremendously due to their unique capabilities including ubiquitous presence, short generation time and the ability to fix atmospheric nitrogen. Cyanobacteria are considered to be a rich source of novel metabolites that are of great importance from an agricultural and industrial point of view. The worldwide increase in population seen over the last decades has contributed to the increasing demand for food supplies, which can only be achieved through improvements in agricultural productivity. Cyanobacterial biomass is an effective biofertilizer source for improving agricultural productivity by boosting soil physicochemical characteristics including mineral nutrient status and water holding capacity of demeaning lands. Environmental quality can also be increased by applying cyanobacteria as a bio-inoculant. They are also being used in the industrial and domestic wastewater treatments for the removal of phosphate, ammonia and other heavy metals such as Cu, Fe, Cr, Ni and Mo. The photoprotective role of cyanobacteria is another important application in industrial sectors. Cyanobacteria have been genetically designed with novel genes to
produce many biofuels such as biodiesel, bio-hydrogen and bio-methane.
The role of cyanobacteria as food products and biofertilizer in
agricultural sectors has prompted researchers to come up with welldefined
applications of cyanobacteria. This chapter is an attempt to enlist
useful facts about cyanobacteria and their possible role in resolving the
agricultural as well as industrial issues in the future welfare of the world.
... Biological control through the addition of microorganisms to the rhizosphere, such as cyanobacteria, can be an effective means of control of certain soilborne diseases of strawberries. Many bacterial species are natural inhabitants of soil and some can fix nitrogen, thus enhancing soil fertility as well as controlling plant disease (Kulik, 1995). The uses of other fungi as control for pathogenic fungi have also been evaluated. ...
Historically, root diseases have been a production-limiting problem for the strawberry industry worldwide. Even though this disease is of great economic importance, the etiology remains unresolved. However, soilborne fungal root pathogens, particularly Pythium and Rhizoctonia spp. have been implicated as major role players. Presence of nematodes in soil and favourable environmental conditions also play significant role in the disease development. Development of integrated disease management strategies is dependent upon a more complete understanding of the etiology, biology and ecology of the disease complex.
... Cyanobacteria have been reported to produce many metabolites, which have been identified as toxins, antibiotics, and protease inhibitors (Rastogi and Sinha, 2009;Schwarzenberger et al., 2010;Singh et al., 2011); some have been chemically characterized as neurotoxins causing the inhibition of acetylcholine esterase and/or functions such as acetylcholine. This is essentially because several cyanobacteria produce various biologically active compounds that could be utilized in the biological control of plant pathogens (Kulik, 1995;Kim, 2006). These bioactive compounds are biologically active molecules that, at low concentrations, affect a living organism, tissue, or cell beneficially or detrimentally (Armstrong et al., 2019). ...
Background
Plant-parasitic nematodes are one of the major constraints to soybean production around the world. Plant-parasitic nematodes cause an estimated $78 billion in annual crop losses worldwide, with a 10–15% crop yield loss on average. Consequently, finding and applying sustainable methods to control diseases associated with soybean is currently in serious need.
Methods
In this study, we isolated, purified, characterized, and identified a novel cyanobacterial strain Oscillatoria sp. (blue-green alga). Based on its microscopic examination and 16S rRNA gene sequence, the aqueous and methanolic extracts of Oscillatoria were used to test their nematicidal activity against Meloidogyne incognita hatchability of eggs after 72 h of exposure time and juvenile mortality percentage in vitro after 24, 48, and 72 h of exposure time and reduction percentage of galls, eggmass, female number/root, and juveniles/250 soil. Also, the efficacy of the extract on improving the plant growth parameter and chlorophyll content under greenhouse conditions on soybean plant cv. Giza 111 was tested. Finally, the expression of PR-1, PR-2, PR-5, and PR15 (encoding enzymes) genes contributing to plant defense in the case of M. incognita invasion was studied and treated with Oscillatoria extract.
Results
The aqueous and methanolic extracts of Oscillatoria sp. had nematicidal activity against M. incognita. The percentage of mortality and egg hatching of M. incognita were significantly increased with the increase of time exposure to Oscillatoria extract 96.7, 97, and 98 larvae mortality % with S concentration after 24, 48, and 72 h of exposure time. The aqueous extract significantly increased the percentage of Root-Knot nematodes (RKN) of egg hatching, compared with Oxamyl and methanol extract at 96.7 and 97% after 72 h and 1 week, respectively. With the same concentration in the laboratory experiment. Furthermore, water extracts significantly reduced the number of galls in soybean root, egg masses, and female/root by 84.1, 87.5, and 92.2%, respectively, as well as the percentage of J2s/250 g soil by 93.7%. Root, shoot lengths, dry weight, number of pods/plant, and chlorophyll content of soybean treated with Oscillatoria water extract were significantly higher than the control increasing by 70.3, 94.1, 95.5, and 2.02%, respectively. The plant defense system's gene expression was tracked using four important pathogenesis-related genes, PR-1, PR-2, PR-5, and PR15, which encode enzymes involved in plant defense.
Conclusions
Oscillatoria extract is a potential nematicide against root-knot nematode invasion in soybean.
... Regarding the horticultural experiment, consumers are increasingly concerned about the link between food safety and human health. In this respect, natural sources (yeast, seaweed extracts, compost, etc.) play a crucial role [31][32][33][34]. Farmers are more interested in using natural sources as bio-control agents in agriculture to provide safe food [35,36]. ...
... Kausalya and Rao [11] pointed out that the presence of antifungal agents in the extraction of seaweeds, for example, Sargassum polycystum and S. tenerrimum may be used to produce innovative agents for the benefit of humankind. Martin [12] tested extracts from large algae on plants and found a significant decrease in the occurrence of strawberry and turnip diseases caused by Botrytis cinerea and Erysiphe polygoni, respectively, owing to the occurrence of a category of biologically effective compounds created by macroalgae. ...
Fusarium wilt caused by Fusarium oxysporum f. sp. lycopersici (FOL) in tomatoes is globally recognized as one of the most significant tomato diseases, both in fields and in greenhouses. Macroalgae contain a diversity of bioactive complexes. This research was carried out to assess the value of the extracts from three macroalgae (Sargassum dentifolium belongs to Phaeophyta, Gracilaria compressa belongs to Rhodophyta, and Ulva lactuca belongs to Chlorophyta) against wilt disease in tomato plants. The fungal pathogen was isolated from diseased tomato plants growing in several parts of Saudi Arabia. Isolates of the pathogen were identified by morphological and molecular methods. Three organic solvents, in addition to water, were used for extraction to assess the effect of reducing FOL hyphal growth on potato dextrose agar (PDA). Radial reductions in pathogen hy-phal growth were seen with all of the solvent and water extracts, but the three macroalgae methanol extracts that were tested showed the greatest reduction in pathogen hyphal growth. The total phenol content of the S. dentifolium extract was higher than that of the other two macroalgae. The phe-nolic compounds showed variability in all of the extracts that were identified and calculated by high-performance liquid chromatography (HPLC). Phloroglucinol (7.34 mg/g dry weight), vanillic acid (7.28 mg/g dry weight), and gallic acid (6.89 mg/g dry weight) were the phenolic compounds with the highest concentrations in the S. dentifolium, G. compressa, and U. lactuca extracts, respectively. The mycelium of FOL treated with a crude macroalgae extract of tested at 100 μg/mL was examined with a scanning electron microscope. The results showed an obvious difference between the extract-treated and untreated hyphae. The extract-treated hyphae collapsed and bruised, as well as; empty and dead. In the greenhouse experiment, S. dentifolium powder was used to evaluate its effect on disease decline. It led to a decrease in disease severity of 40.8%. The highest total yield (560.8 g) was obtained from the plants treated with S. dentifolium powder. We recommend the use of macroalgae extracts to combat fungal phytopathogens. Because chemical fungicides are extremely toxic to humans and the environment, macroalgae extracts are a good alternative that can be widely and safely used in the field .
... Increasing concentrations of glutamic acid, seaweed extract and selenium in the study were associated with the promotion. The effect of glutamic acid and seaweed extract on stimulating growth characters could be due to their essential actions on enhancing cell division and the biosynthesis of organic foods [27,28]. In this respect, selenium was able to promote plant growth and improve leaf area of Valencia orange and Zagloul date palms [19,20]. ...
... Продукты метаболизма цианобактерий проявляют антифунгальную активность по отношению к таким широко распространенным патогенным грибам, как Candida albicans, Penicillium notatum, Aspergillus oryzae, Trichophyton mentagrophytes, Ustilago violacea, Sclerotinia sclerotiorum, Rhizoctonia solani и др. Специфической антифунгальной активностью обладают многие биологически активные соединения, выделенные из биомассы цианобактерий, относящихся к Nostocales и Lyngbya [Kulik 1995]. Идентифицированы и запатентованы метаболиты цианобактерий, подавляющие развитие грибов -патогенов сельскохозяйственных культур [Prasanna et al. 2010]. ...
Книга посвящена цианобактериям, древнейшим обитателям нашей планеты. Отличаясь особой жизнестойкостью, они существуют во всех регионах Земли при самых разных климатических условиях. Цианобактерии играют значительную роль в экологии биосферы, морей, океанов, иных водоемов, в сельскохозяйственной экологии, в геоэкологии и др. В книге обобщены материалы о строении
и метаболизме цианобактерий, их систематике и методах идентификации. Дана характеристика цианотоксинов и процессов их образования, их распространения в природных экосистемах, их роли в патологии человека и животных. Рассмотрены клинические данные острых и хронических заболеваний, вызванных токсичными метаболитами цианобактерий. Особое внимание уделено образованию
цианобактериями метаболитов, которые могут быть использованы в народном хозяйстве, для фармацевтических целей, как продукты питания человека и животных, в целях биоремедиации. Рассмотрены условия, которые способствуют развитию цианобактерий в водной среде и почвах, особенности воздействия их интенсивного размножения на окружающую среду. Приведены методы регуляции их развития, способы очистки воды как от самих цианобактерий, так и от их метаболитов. В книге подчеркивается ограниченность существующих пред-
ставлений о цианобактериях и их метаболитах. Формулируются те направления исследований, результаты которых способствовали бы положительному влиянию
цианобактерий на окружающую среду, применению их метаболитов в различных областях, в том числе для целей здравоохранения. Книга рассчитана на экологов и специалистов иных дисциплин, интересующихся цианобактериями.
... They are simple in cell structure, photosynthetic, oxygen budding, and poses both characteristics of microbes and higher plants. It constitutes a tremendous prospective reservoir for food, fuel, feed, fertilizer, medicine, and biochemical (Gustafson et al., 1989;Sundararaman et al., 1996;Kulik, 1995;Soltani et al., 2005;Carmichael, 1994). ...
Bioremediation is considered to be a less expensive and effective alternative to the physicochemical methods for degrading the chemical pesticides or industrial effluents. Several microorganisms are capable of degrading harmful chemical pesticides, i.e., bacteria, actinomycetes, fungi, as well as cyanobacteria. However, the main advantage of using cyanobacteria is its ability to sustain in harsh environments and making the environment clean. Also, their phototropic nature, mastery of nitrogen fixation, and capability to produce bioenergy makes them a potential candidate for the sustainable future. Some possible cyanobacterial genera like nostoc, spirulina, anabaena, etc., have been reported to have the ability of toleration and degradation of various types of herbicides and toxic pollutants of the marine ecosystem. This chapter will focus on different cyanoremediation aspects of the agroecosystem, radioactive compounds, heavy metals, wastewater effluents, etc. Future scope concerning energy generation will also be highlighted.
... These natural materials in addition to their lethal activities on pests preserve the environment of pollution, maintain the equal distribution of fauna, and also keep the beneficial animals (Abdel-Raouf et al., 2012). Fungi and bacteria are the main biological agents that have been studied for the control of plant pathogens, particularly soil-borne fungi (Kulik, 1995). ...
... The antibacterial and antifungal effects of cyanobacteria thus represent a promising approach to suppress, or at least minimize, plant diseases caused by pathogenic organisms. Nevertheless, it must be noted that most studies only investigate the in vitro effect of extracts and this does not automatically imply any effect in vivo [110]. ...
Cyanobacteria are ubiquitous phototrophic prokaryotes that find a wide range of applications in industry due to their broad product spectrum. In this context, the application of cyanobacteria as biofertilizers and thus as an alternative to artificial fertilizers has emerged in recent decades. The benefit is mostly based on the ability of cyanobacteria to fix elemental nitrogen and make it available to the plants in a usable form. However, the positive effects of co-cultivating plants with cyanobacteria are not limited to the provision of nitrogen. Cyanobacteria produce numerous secondary metabolites that can be useful for plants, for example, they can have growth-promoting effects or increase resistance to plant diseases. The effects of biotic and abiotic stress can as well be reduced by many secondary metabolites. Furthermore, the biofilms formed by the cyanobacteria can lead to improved soil conditions, such as increased water retention capacity. To exchange the substances mentioned, cyanobacteria form symbioses with plants, whereby the strength of the symbiosis depends on both partners, and not every plant can form symbiosis with every cyanobacterium. Not only the plants in symbiosis benefit from the cyanobacteria, but also vice versa. This review summarizes the beneficial effects of cyanobacterial co-cultivation on plants, highlighting the substances exchanged and the strength of cyanobacterial symbioses with plants. A detailed explanation of the mechanism of nitrogen fixation in cyanobacterial heterocysts is given. Finally, a summary of possible applications of co-cultivation in the (agrar-)industry is given.
... Several types of algae have been reported to inhibit soil-borne fungus, including Anabaena spp., Scytonema spp., and Nostoc spp.. The mycelial growth of plant pathogenic fungus was entirely suppressed by extracts from certain algae (Galal et al., 2011;Kulik, 1995). ...
In pursuit of an environmentally benign fungicide alternative, the current study explored the antifungal activity of Chlorella vulgaris extracts against six plant pathogenic fungi (in vitro). The well diffusion agar method was used to investigate the growth inhibition of Fusarium oxysporum, Fusarium sp., Fusarium solani, A. flavus, A. niger, and A. alternata using the three C. vulgaris extracts viz. methanol (CvME), acetone (CvAE), and diethyl ether (CvDE). Different concentrations of CvDE were also investigated against F. oxysporum. The morphological modifications in F. oxysporum treated with CvDE (5mg/kg) were studied using SEM and the chemical composition of CvDE was also determined by GC-MS analysis. All extracts, with the exception of A alternata, were found to be effective in inhibiting the growth of plant pathogenic fungi. The CvDE extract, followed by CvME and CvAE, was found to be efficient against tested fungi. The CvDE was most effective against F. oxysporum with a 73.3% growth inhibition. The effects of various CvDE concentrations on F. oxysporum were found to be dosage dependent. The SEM micrograph revealed that CvDE-treated F. oxysporum had substantially less conidia than the control. The CvDE treatment damaged the mycelial structure as well. Major chemical components detected in CvDE were Heptaldehyde (15.7%), Octadecenoic acid, methyl ester (12.6%), Hexadecanoic acid (12%), 3-Decyn-2-Ol (10.98%), (E)-3,7,11,15-tetramethylhexadec-2-ene (9.76%), heptadecane-1,2,3,4,5-pentol (8.7%), Docosane, 4-methyl (7.28%).
Two experiments were conducted to develop a Nano green manganese and assess its effect on grapevines. The first experiment was microbiological, where several incorporation strategies were utilized to enrich the yeast with manganese, as follows: (1) adding manganese to the liquid medium (growth phase), (2) adding after 24 h of incubation (non-growth phase). As the results, growth phase reduced the possibility of medium contamination. Manganese concentration in the yeast cells was increased as that of manganese sulphate in the medium. Manganese incorporation in yeast cells was 99.93% higher than that of the medium at 0.0195 g/l of manganese. Although the concentration of manganese in the medium raised the OD of yeast cell biomass, manganese sulphate had no passive influence on it. The second experiment was horticultural, done on Flame Seedless grapevines, since both active fresh and frozen yeast enriched with manganese resulted from the first experiment were sprayed twice a year at 10 or 20 cm3/l comparing with manganese sulphate, and manganese chelate. The results demonstrated that yeast extracts in both forms increased the yield and improved fruit properties. The most effective treatment on vegetative growth, yield and fruit properties was the frozen yeast enriched with manganese at 20 cm3/l.
Microalgae are a source of scientific curiosity and inspiration for their utilization as ‘inoculants’ in agriculture and the commercial production of high-value products. Their diversity and abundance in the soil environment highlight the fact that these integral members of the soil microbial community modify the physical and chemical conditions of soils and interact with other microorganisms and even with higher plants with varying degrees of association. However, to date, the agronomic benefits of the nitrogen fixation trait of cyanobacteria have not been fully realized. Thus, the ecological functions of these organisms in the biological soil crusts should be thoroughly evaluated and widely applied given that climate change events can increase desertification. Currently, the crop yield increments and pest control due to these biostimulants and the reclamation of saline and sodic soils by these bioameliorants are considered economically marginal. Similarly, the carbon capture and storage by eukaryotic microalgae and cyanobacteria in soils are poorly understood. Limitations in their commercial production for agricultural use include inadequate technological innovations and the enormous expectation for yield increments, together with the contemporary monetization of their environmental benefits. Thus, this critical review presents the desirable reappraisal of their agronomic benefits and the invigoration of research and culture collections to utilize these organisms or their metabolites, considering the evolutionary consequences and environmental advantages and finally their commercial production for widespread application in agriculture.
Microalgae are one of the impressive life forms. Since microalgae are a photosynthetic organism, they are produced in conditions which include light, water, CO 2 , nutrients and with proper temperature and pH. Hence, the cultivation circumstances of microalgae are of great importance for maximum production. Lately, microalgae are in the spotlight for biofuel generations, microalgal compounds and industrial uses. Furthermore, biofuels created from microalgae are recognized as the most important renewable sources of industrial manufacturing. This chapter explicates general information about algae, and systems used to cultivate microalgae for these applications and future research.
Soils are the environments used by significant types of organisms, for example, microbes, archaea, algae, fungi, insects, annelids and plants. The wayfaring utilization of different synthetic substances to upgrade agronomic efficiency prompted grave outcomes like structural unsteadiness, the assembly of hazardous contaminants and so forth, prompting a biological lopsidedness between soil, vegetation and microbes. Nonetheless, the main job of microalgae and cyanobacteria to compensate for the yield of plants and other possible arrays stays unexplored yet. The purpose of this chapter is to feature the importance of this novel group of microorganisms with regard to fertility and health of the soil. This interesting group of photosynthetic eukaryotic organisms additionally has solicitations in current farming trends through promising and prolonged nutrient expediency, synchronizing natural carbon and soil fertility and improving plant development and harvest yields, because of incitement of soil microbial enactment. Microalgae are betrothed with the formation of metabolites, for example, growth hormones, polysaccharides, antimicrobial composites and so forth, which undertake a significant job in the plant colonization and multiplication of microbial and eukaryotic organisms in soil.KeywordsBiopesticidesCyanobacteriaMicroalgaeNitrogen fixationPhytohormonesSoil fertility
In view of their broad color variation and superior antioxidant activity, carotenoids are widely used in the food, cosmetic, pharmaceutical, and feed industries. Cyanobacteria are well-known producers of commercially important carotenoids, such as β-carotene and zeaxanthin. Furthermore, metabolic engineering of cyanobacteria for the production of valuable carotenoids, such as astaxanthin and lutein, has garnered significant interest in recent years because it offers the advantages of simple cultivation, harvesting, and genetic manipulation. This chapter describes the potential of cyanobacteria as carotenoid producers, the applications of carotenoids, the biological activities exhibited by carotenoids (e.g., antioxidant, cardioprotective, and anticancer), and the recent progress in carotenoid processing technology (e.g., extraction, formulation, and isomerization).
In this present situation, the ongoing pressure to reduce the use of pesticides and synthetic fertilizer inputs is a major challenge for sustainable agriculture. Microbial applications are a safe and renewable mode in the maintenance of agricultural productivity. Algae are acknowledged for their wide application ranging from agriculture to industries. They play a crucial role in sustainable agriculture and are used as bio-fertilizer and soil stabilizers, decreasing the need for synthetic fertilizers. The major focus is laid on the role of algae, microalgae, and cyanobacteria in soil fertility and their beneficial roles in agriculture and the maintenance of environmental sustainability.
Our ever-increasing population has inflicted enormous amount of pressure on agriculture sector. To meet the increased food demands, use of synthetic pesticides and fertilizers has been favored since Green Revolution. Lately repercussions of these chemical pesticides have been observed, they negatively impact environment by leaching to groundwater and also have an unenviable effect on non-targeted organisms. These are potentially toxic to humans as well, a study in Punjab disclosed that because of the excess use of carcinogenic pesticides like DDT and Lindane, there are 90% cancer patients per 1 Lakh people compared to the national average of 80%. The chemical pesticide intensive agriculture also envisages a high cost of agricultural production and over exploitation of natural resources such as water and soil. Hence shifting towards sustainable and cost-effective alternative seems mandatory, this can be achieved by use of biologically-active compounds that have proven abilities in crop protection. Microalgal and Cyanobacterial biomass (or their extracts) are gaining particular attention in this arena, they have demonstrated undeniable potential as a source of essential nutrients and metabolites with different bioactivities, which can significantly improve crop productivities. A biomass extract from Nostoc can kill Helicoverpa armigera larvae at a dose of 2.20 mg/cm2. The antimicrobial substances produced includes nostocyclyne A, nostofungicidin, nostocin A, Ambigol A and B, hapalindoles, tjipanazoles and scytophycins and exhibit fungicidal activity against plant pathogens. The biocontrol agents present in cyanobacteria depicts diversified application in improving the farming practices in modern day agriculture. This manuscript anchors the prospective role of cyanobacteria and its by-products in agricultural pest management and its impact on environment.
An increasing human population necessitates more food production, yet current techniques in agriculture, such as chemical pesticide use, have negative impacts on the ecosystems and strong public opposition. Alternatives to synthetic pesticides should be safe for humans, the environment , and be sustainable. Extremely diverse ecological niches and millions of years of competition have shaped the genomes of algae to produce a myriad of substances that may serve humans in various biotechnological areas. Among the thousands of described algal species, only a small number have been investigated for valuable metabolites, yet these revealed the potential of algal metabolites as bio-pesticides. This review focuses on macroalgae and microalgae (including cyano-bacteria) and their extracts or purified compounds, that have proven to be effective antibacterial, antiviral, antifungal, nematocides, insecticides, herbicides, and plant growth stimulants. Moreover, the mechanisms of action of the majority of these metabolites against plant pests are thoroughly discussed. The available information demonstrated herbicidal activities via inhibition of photosyn-thesis, antimicrobial activities via induction of plant defense responses, inhibition of quorum sensing and blocking virus entry, and insecticidal activities via neurotoxicity. The discovery of antime-tabolites also seems to hold great potential as one recent example showed antimicrobial and herbi-cidal properties. Algae, especially microalgae, represent a vast untapped resource for discovering novel and safe biopesticide compounds.
Tropical marine algae have proven to be a rich source of bioactive compounds with biomedicinal potential. Marine algae with topical cleansing (Reichelt & Borowitzka, 1984), antifungal (Welch, 1962; Moreau et al., 1984), antineoplastic (Mayer & Panick, 1984; Patterson et al., 1984), antifertility (Naqvi et al., 1980), and antiviral, including anti- herpes (Ehresmann et al., 1977, 1979; Hatch et al., 1979; Naqvi et al., 1980; Caccamese et al., 1980, 1981; Rinehart et al., 1981; Yamamoto et al., 1982) activities have been reported. Hoppe (1979) reviewed the broad worldwide usage of algae in folk medicine.
Seventy one species of marine macrophytes from the Central Mediterranean have been screened for the production of antibacterial, antifungal, antiviral, cytotoxic and antimitotic compounds. Sixty five of the species displayed some kind of activity and most of them were active on more than one organism or cell tested. Antifungal activity was the most widespread (70% of the plants), whilst the incidence of antibacterial activity was extraordinarily low (6% of the plants). Of the plants tested 21% showed antiviral activity, 35% were cytotoxic and nearly 50% had antimitotic properties. The maximum level of activity was found among the Chlorophyfa; some members of the Bryopsidales (Flabellia petiolata, Caulerpa prolifera, Halimeda tuna) were the most active species. Most of the dominant species in Mediterranean phytobenthic communities (Corallina elongata, Lithophyllurn lichenoides, Phyllophora crispa, Cystoseira spp., Halopteris spp., Codium spp., Halimeda tuna, Valonia utricularis, Posidonia oceanica, Zostera noltii and Cyrnodocea nodosa) exhibited strong antifungal properties.
We tested “Roots” (Lisa Products Corp., New Haven, Conn.), a proprietary mixture of humic acids, marine algae extracts, thiamine, and ascorbic acid. The objective of this study was to assess the effectiveness of this organic biostimulant (OB) on pod production of green beans (Phaseolus vulgaris L.).
Seeds of beans cv. Bush Blue Lake 274 (Agway Inc., Syracuse, N.Y.) were sown and germinated in trays filled with vermiculite. In test A, the first set of 120 seedlings was transplanted, one seedling per pot, to 2.8-liter pots that contained a 1 potting soil (Agway) : 1 vermiculite (v/v) mix. The fresh weights of the pods of all biostimulant-treated groups were significantly higher than those of the control (P < 0.05). In test A, the values were 14% and 16% over the control, respectively, and in the validation test (test B), fresh weight for OB at 1% was 18% higher than that of the control. The fresh weights were similar for
OB at 1% and 3% in test A. No vegetative growth differences were observed in these experiments, and pod water content (mean 92%) was similar for all treatments.
The book describes the biological ways in which diseases of plants, caused by pathogenic microbes, can be controlled without the use of chemical pesticides. The basis of biocontrol (in microbiology, ecology and plant pathology) is described and many examples of control measures in commercial use or development are given. There is increasing interest in biocontrol from the general public, environmentalists and the major world agrochemical companies, and this easily read text presents recent developments in the subject. The book provides enough references and literature citations to allow a more detailed investigation of particular diseases or control systems to be made. This textbook is suitable for graduate and undergraduate students in botany, biology, microbiology, plant pathology, agriculture, horticulture, crop science, microbial ecology, crop protection and related courses.
Ways of stimulating soil algae, an agronomically important part of the soil biota, are reviewed, including by: 1) agricultural practices and reclamation (soil cultivation, crop rotation, fertilization, regulation of the water regime, liming, use of pesticides, etc), and 2) "algalization', ie inoculation of soil with live algae and their metabolites. -Journal summary
Liquified seaweed, marketed in the U.K. as “Maxicrop” and the U.S.A. as “Seaborn”, although having no direct insecticidal or fungicidal effect, has been shown to increase the resistance of crop plants to certain pests and diseases. These include aphids, red spider mites, powdery mildew, botrytis and an unidentified complex of fungi responsible for the damping-off of seedlings.
In recent years there have been considerable changes in attitude towards the use of chemicals in agriculture. Increasing public awareness concerning the quantities and types of chemicals used and their potential impact on the environment has led to more stringent regulations on their use and, in some cases, removal from the market. Consequently, interest has focused on alternatives to chemicals, particularly for pest and disease control. The use of biological disease control measures is one of the strategies available and much experimental work is being carried out to assess its commercial applicability.
Gloiosiphones A [1] and B [3] have been isolated from the temperate red marine alga, Gloiosiphonia verticillaris. Gloiosiphone A possesses a new C10 carbon skeleton composed of a 1-methylspiro[4.4]nonane ring, trivially termed the gloiosiphane ring system. It was isolated as the dimethyl derivative 2 obtained upon treatment of the crude antimicrobial fractions with CH2N2. Metabolite 3 is a structurally related C5 natural product. The structures of 2 and 3 were assigned on the basis of spectral analysis.
The δ-lactone malyngolide, an antibiotic effective against Mycobacterium smegmatis and Streptococcus pyogenes, was isolated from the dichloromethane extract of a shallow-water variety of the blue-green alga Lyngbya majuscula Gomont. Its skeletal structure and relative stereochemistry were established by spectral analysis, chemical degradation, and a lanthanide-induced proton chemical shift study. The absolute configuration was determined by a circular dichroism study and by converting malyngolide to levorotatory methyl 2-methyl-5-oxotetradecanoate which had an optical rotation comparable with that of methyl 2(R)-methyl-5-oxoheptanoate. The structure was verified by X-ray crystallographic analysis of the levorotatory saponification product, (2R,5S)-5-hydroxy-5-(hydroxymethyl)-2-methyltetradecanoic acid.
This study is part of an investigation into the occurrence of plant growth substances in marine unicellular algae. Auxins and gibberellins have previously been detected. This paper reports the occurrence of phytokinins in algae, using the radish leaf test.
The technique of the test is described and a few modifications examined. Radish leaves were shown to be more responsive than swede leaves. Some requirement for a minimum temperature below 7° C during the growing period of the plants appeared to be a factor for maximum response. The size and age of the leaf were shown to influence kinetin activity. Chemicals tested included benzyl adenine, a 9-substituted benzyl adenine, and kinetin. Kinetin showed lower activity than the benzyl adenines. Kinetin kept in the solid state at −20° C for 2 years was as active as freshly prepared kinetin. Gibberellic acid (GA2) at 10⁻⁵ g/ml sometimes showed activity equivalent to 10⁻⁵ g/ml kinetin. Indole-3-yl acetic acid at concentrations of 10⁻⁴ to 10⁻⁶ g/ml was inactive.
The radish leaf test was successfully used to demonstrate phytokinins in extracts of two species of unicellular marine algae, and in marine phytoplankton samples. Amounts found were within the range 0.1 to 1.0 mg/kg with one exception of 10 mg/kg. Phytokinin activity in these extracts decreased over a period of a few weeks when stored at −20° C.
This article presents the current status of chemical research on the toxins of freshwater and marine blue-green algae. The author gives brief historical accounts of the isolation and identification of (a) anatoxins from Anabaena flos-aquae, (b) saxitoxin and related compounds from Aphanizomenon flosaquae, (c) polypeptides from Microcystis, (d) debromoaplysiatoxin from Oscillatoriaceae, and (e) lyngbyatoxin from Lyngbya majuscula.
The antibiotic properties of Chlorococcum humicolum (Naeg) Rabenh. (Chlorophyceae) have been investigated. The alga contains a wide spectrum antibiotic substance, which forms zones of inhibition up to 30·5 mm wide. Of the seven test organisms studied, it is effective against Cryptococcus neoformans, Bacillus pumillus, Escherichia coli, Sarcina lutea, Bacillus subtilis and Staphylococcus aureus.
A thermotolerant species of Phormidium produced extracellular anti-microbial material during batch culture. Although this material was inactive when screened against a number of other cyanobacteria, it inhibited the growth of a wide range of Gram-positive and Gram-negative heterotrophic bacteria, Candida albicans and Cladosporium resinae.
In biological agriculture and horticulture diluted extracts of seaweed are applied to promote growth, prevent pests and diseases and improve the quality of the products. The efficacy of the extracts is probably based upon plant hormones (mainly cytokinins) and trace nutrients present in the extracts. A survey of the recent literature is given concerning the properties of seaweed extracts, methods of application, their effects and putative working mechanisms. The significance of seaweed extracts in biological agriculture and horticulture is evaluated, regarding environmental aspects of production and use.
The tropical marine cyanobacterium Hormothamnion enteromorphoides produces a suite of cytotoxic and antimicrobial cyclic peptides. The structure of the most lipophilic of these, hormothamnin A, was determined by interpretation of physical data, principally high NMR and FAB MS, in combination with chemical derivitization and degradation schemes. Isolation of a key pentapeptide fragment DPHE-D-LEU-L-ILE-D-allo-ILE-L-LEU, obtained under partial hydrolysis conditions, was instrumental to the final structure determination. β-D-aminooctanoic acid (D-BAOA) was characterized as a per-ester derivative following complete acid hydrolysis and Z-didehydrohomoalanine (DHHA) was spectroscopically in the intact peptide. The remaining residues (HYPRO, 2 × HSER, GLY) were evident from amino acid and spectroscopic analysis. Sequencing of these residues made use of knowledge from fragments, high field NMR (NOESY and ROESY) and FAB MS analysis of the intact peptide. Absolute stereochemistries of the α-amino residues were determined by HPLC analysis of the acid liberated residues derivatized with Marfey's reagent. The absolute stereochemistry of the β-amino residue was shown by circular dichoroism analysis, HPLC analysis of the Marfey derivative, and chiral synthesis of a homolog. By these techniques, hormothamnin A was demonstrated to possess a cyclo-[D-PHE-D-LEU-L-ILE-D-allo-ILE-L-LEU-GLY-D-BAOA-L-HSER-DHHAL-HYPRO-L-HSER] structure.
Bioactivity-directed isolation of the extract of the cyanophyte Tolypothrix tjipanasensis has led to the isolation of fifteen new N-glycosides of indolo[2,3-a]carbazoles designated tjipanazoles A1, A2, B, C1, C2, C3, C4, D, E, F1, F2, G1, G2, I and J. The structures of the alkaloids were determined by physical methods, chemical degradation and synthesis. Tjipanazole J is the only compound having the pyrrolo[3,4-c] ring of previously described indolo[2,3-a]carbazoles.
It is often claimed that application of seaweed extract, which contains plant growth regulators, can be beneficial in crop production. The present paper gives details of trials carried out in Victoria, Australia in the 1981 — 1982 growing season. A commercially available extract made by alkaline hydrolysis of Ascophyllum nodosum was applied to lettuce and cauliflower plants. It is concluded that when applied at the recommended rates beneficial effects in yield are obtained. In the case of the lettuce plants seaweed extract application caused a significant decrease in the number of lettuce failing to form hearts and a significant (at the 99 per cent confidence level) increase in the weight of marketable lettuce and in their mean heart diameter. In the case of cauliflower plants seaweed extract application led to a significant increase in curd diameter.
Culture filtrates and organic solvent extracts of 132 marine and 400 freshwater microalgal cultures produced a total of 18 and six inhibitory effects, respectively, when screened against six test fungi. These results indicate that marine microalgae show more potential in the search for new antifungal agents than do freshwater species. No taxonomic trends were seen in the results. Organic solvent extraction of algal biomass appeared to be the most effective means of producing these inhibitory effects.
Dechlorofontonamide, anhydrohapaloxindoles B and M, and hapalonamides G, H, and V have been isolated as minor indole alkaloids from a cultured strain of the terrestrial blue-green alga Hapalosiphon fontinalis.
On the basis of a comparative study of 178 strains of cyanobacteria, representative of this group of prokaryotes, revised definitions of many genera are proposed. Revisions are designed to permit the generic identification of cultures, often difficult through use of the field-based system of phycological classification. The differential characters proposed are both constant and readily determinable in cultured material. The 22 genera recognized are placed in five sections, each distinguished by a particular pattern of structure and development. Generic descriptions are accompanied by strain histories, brief accounts of strain properties, and illustrations; one or more reference strains are proposed for each genus. The collection on which this analysis was based has been deposited in the American Type Culture Collection, where strains will be listed under the generic designations proposed here.
Experiments were carried out to define the effect of mixing upon primary productivity. The method compares the production of a water column with C-14-labelled samples (i) along a classic vertical profile and (ii) with a rotating system moving between the surface and the bottom of the pond, which was 0.5 m deep. In all the experiments, photosynthesis was best in the moving flask. The effect of mixing is particularly important at sunrise and sunset hours: the vertical photosynthetic budget may be over 2.5 times that of homogeneous non-turbulent water. These results have clear implications for monitoring intensive outdoor algal cultures.
Three different solvents viz. benzene, chloroform, and methanol have been used successively to obtain crude extracts from five different algae. These extracts were tested against both gram-positive and gram-negative bacterial strains for their antibacterial activity. The chloroform extract exhibited the greatest antibacterial activity
Extracts of Dilsea carnosa, Laurencia pinnatifida, Odonthalia dentata and Polysiphonia lanosa reduced the rate of colony extension in Microsporum canis and Trichophyton verrucosum, with seasonal variations in the levels of inhibitory activity. Antifungal activity was not detected in any extract of Chondrus crispus, although some stimulation of colony extension in M. canis was recorded. None of the algal extracts exhibited antifungal activity against Aspergillus flavus, A. fumigatus or Candida albicans.
Phenolic compounds were determined in methanolic extract from the algal mass of aNostoc muscorum culture. Bioassays with two human pathogens,Candida albicans andStaphylococcus aureus indicated that algal phenolic compounds evoked significant growth inhibition for both species (89.1% and 88.2%, respectively). It is suggested that this strong inhibitory effect is of potential medicinal value.
Eighteen new indole alkaloids, hapalindoles C-Q and T-V, have been isolated from the cultured cyanophyte Hapalosiphon fontinalis. The gross structures and relative stereochemistries of these 18 minor hapalindoles have been determined by using spectral methods. The relative stereochemistries of hapalindoles A, D, and K have been confirmed and the absolute configuration of hapalindole K has been established as 11R,12R,13R by X-ray crystallography. Assuming that all of the alkaloids have the same absolute stereochemistry as K, all of the hapalindoles isolated to date are 11R and all of the chlorine-containing ones are 13R. With the exception of hapalindole L, all of the hapalindoles are 12R. Hapalindoles A and B, the major alkaloids in the blue-green alga, and several of the minor hapalindoles are 10R,15S. Some of the alkaloids, however, viz. C-G and U, are 10S,15S and two, viz. H and Q, are 10R,15R. Most of the hapalindoles are tetracyclic, but C-F and Q are tricyclic; none of the tricyclic hapalindoles isolated to date, however, are 10R,15S. Hapalindole T is an unusual thiocarbamate and hapalindole V is 10-hydroxyhapalindole G.
The lipophilic extract of the cultured terrestrial blue-green alga Scytonema pseudohofmanni Bharadwaja contains five novel macrolides, scytophycins A (1), B (2), C (3), D (4), and E (5), which exhibit cytotoxicity and antifungal activity. The structures of 1-5 have been determined mainly from spectroscopic data. The relative stereochemistries of the scytophycins are based on an X-ray crystallographic analysis of a transformation product of scytophycin C (8) and comparison of the 1H and 13C NMR spectra of 1-5. The absolute stereochemistries of the scytophycins have been deduced from a circular dichroism study of the dibenzoate ester 16, obtained in five steps from scytophycin B, and comparison of the CD curves of 1-5. These novel secondary metabolites appear to be biogenetically related to the marine natural products swinholide A, ulapualides A and B, and kabiramide C.
A broad-spectrum fungicide, calophycin, has been isolated from Calothrix fusca EU-10-1, a terrestrial blue-green alga belonging to Nostocaceae, and identified to be a cyclic decapeptide, cyclic (L-Ala-D-Asp-L-Asn-L-Gln-Gly-L-Arg-L-N-MeAsn-L-Pro-(2R,3R,4S)-Hamp-L-Val), where Hamp is a (2R,3R,4S)-3-amino-2-hydroxy-4-methylpalmitic acid unit and MeAsn is an N-methylasparagine residue. Its total structure, including absolute stereochemistry, was determined by a combination of spectral and chemical studies, including synthesis of the unusual β-amino acid Hamp.
The isolation and structural elucidation of ambiguine isonitriles A-F from the terrestrial cyanophytes Fischerella ambigua UTEX 1903, Hapalosiphon hibernicus BZ-3-1, and Westiellopsis prolifica EN-3-1 are described. The structures of A-F were determined by spectroscopic methods and confirmed for indolenine D by X-ray crystallography. The new alkaloids are characterized by an additional isoprene unit attached to C-2 of the indole moiety. In ambiguines D-F the isoprenyl substitutent is further fused to the isonitrile-bearing carbon.
Algae are a large and diverse group of organisms from which a wide range of secondary metabolites have been isolated. A number of these compounds possess biological activity such as toxicity, antibacterial, antifungal, antiviral, antitumour and other specific activities. An indication of the range and diversity of algal metabolites and their biological activities is given and the potential of algae as a source of useful biologically active products is discussed.