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Light microscopy pictures of Navicula sp. (Nsp, left panels), Dunaliella viridis (Dv, middle panels), and Dactylococcopsis salina (Ds, right panels) at the exponential growth phase in high salinity (HS) and low salinity (LS), (A-C) and (D-F) respectively. The cellular length in the different samples in the two conditions is shown in the bar graph (G). Measurements were done in triplicate (n = 3), obtained average and standard deviation values are shown in the graphs.
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Halophilic microorganisms inhabiting hypersaline environments such as salt lakes, Dead Sea, or salt evaporation ponds, have acquired specific cell adaptation to grow within stressful conditions. In this study, we isolated heterotrophic and autotrophic microorganisms from several saltern ponds located at the Natural Reserve “Saline di Trapani e Pace...
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... morphological changes of the photosynthetic microorganisms (i. e. Nsp, Dv, Ds) in LS and HS are shown in Fig. 3. Nsp is a pennate diatom with a length range of 10-20 μm; this unicellular alga in HS condition appeared with yellowish plastids (Fig. 3A and D), confirming previous findings [27]. Dv is a unicellular flagellate green alga of the genus Dunaliella with a smaller cell dimension (~12 × 8 mm) able to change its volume and shape in response ...
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... morphological changes of the photosynthetic microorganisms (i. e. Nsp, Dv, Ds) in LS and HS are shown in Fig. 3. Nsp is a pennate diatom with a length range of 10-20 μm; this unicellular alga in HS condition appeared with yellowish plastids (Fig. 3A and D), confirming previous findings [27]. Dv is a unicellular flagellate green alga of the genus Dunaliella with a smaller cell dimension (~12 × 8 mm) able to change its volume and shape in response to osmotic stress [28]. Here, under HS condition, they showed an increase of about 40% on their volume (~20 × 10 mm) ( Fig. 3B and E). Ds cells ...
Context 3
... yellowish plastids (Fig. 3A and D), confirming previous findings [27]. Dv is a unicellular flagellate green alga of the genus Dunaliella with a smaller cell dimension (~12 × 8 mm) able to change its volume and shape in response to osmotic stress [28]. Here, under HS condition, they showed an increase of about 40% on their volume (~20 × 10 mm) ( Fig. 3B and E). Ds cells are non-motile with a spherical or ovoid shape, 8-10 μm in length, and showed different coloration with salinity level: they were blue-green in LS and yellow-green in HS (Fig. 2C and F). Changes in salinity conditions are already known to induce physiological modifications in diatoms and benthic organisms ...
Citations
... These bacterial halophiles are present in saline environments may be saline soils and salty lakes, and oceans/seas. The presence of extreme halophiles in seawater in Spain, Italy, and the Basque Lakes, British Columbia, Canada is reported by Martínez et al. (2022), Villanova et al. (2021);and Fox-Powell and Cockell (2018) respectively; in the hypersaline lake, Siwa oasis, Egypt by Elsaied et al. (2017); in Indonesia by Chasanah et al. (2020), and from Indian salterns by Rathakrishnan and Gopalan (2022). ...
Microbes including bacteria play an important role in their habitat, some roles are known, and yet others are to be discovered. These bacteria are known to be present in several ecosystems and environments including glaciers and oceans on the earth. The bacteria present in the salty water of the ocean and sea are termed bacterial halophiles due to their ability to grow in saline environments and are important in the regulation of this environment of the sea. However, all the beneficial activities of these halophiles have not been reported yet. In the present investigation, we studied the bacterial halophiles of the Arabian Sea in India, at two locations. At least 3 distinct bacterial halophiles were present in Arabian Sea water at Mumbai, while 5 distinct bacterial halophiles were present in the same Arabian Sea water at Dahanu beach in Palghar district. Based on their salt tolerance limit, these were moderate halophiles (8 % salt tolerance) and extreme halophiles (25 % salt tolerance) and were observed to be of different colony morphology at these locations. These were found to have a beneficial activity viz. to increase the pH (i.e. decreased the acidity in the range of 0.36-0.82) and decrease in electrical conductivity (EC: in the range of 0.46-0.88) of its saline growth medium. These bacterial halophiles were tested for their ability in the rectification of saline soils under in vitro studies. It was apparent from the result that the isolates of bacterial halophiles were capable of lowering the EC of saline soil, although not to the level of the required EC (<4) of normal cultivable soil. Therefore, further studies are required on the use of halophiles to achieve a lower EC of <4 in saline soils to make these suitable for crop cultivation. The use of bacterial halophiles in salt-affected soils for their reclamations can be a new area in microbial research.
... Moreover, Providencia stuatrti sp. and Lysinibacillus fusiformis sp. were isolated from high-salt environments [38]. From saltern ponds in Trapani, Sicily, Halomonas sp., Salinibacter ruber, and Brevibacterium sp. have been isolated [66]. Various bacterial and archaeal halophiles were isolated from a hypersaline lake in the south of Tunisia, and identified as Salicola sp., Bacillus sp., Halorubrum sp., Natrinema sp., Haloterrigena sp. ...
... Also, Marinococcus, Salinibacter, and Cytophaga were isolated from solar salterns of Tamil Nadu, India [72]. Furthermore, similar halophilic bacteria such as Salinibacter ruber, Brevibacterium sp. and Halomonas sp. have been isolated from saltern ponds of Trapani, Sicily [66], and Salinivibrio kushneri has been isolated from salterns, Spain [73]. Although many species belonging to the recovered genera have been described in previous studies, our findings spotlighted the diversity of these strains with emphasis on their extracellular enzymatic activity. ...
Halophilic bacteria are promising reservoirs for halotolerant enzymes that have gained much attention in biotechnological applications due to their remarkable activity and stability. In this study, 62 halophilic bacterial strains isolated from a solar saltern were screened for the production of various extracellular enzymes. The results revealed that 31 strains (50%) were positive for amylase production while 26 strains (41.9%) were positive for protease. Further, 22 strains (35.48%) exhibited β-glucosidase activity and only 17 (27.41%) demonstrated lipase activity. Of the investigated halophiles, ten strains growing in the presence of ≥15% NaCl (w/v) were selected and identified based on their 16S rRNA gene sequences as Halomonas meridiana, Salinivibrio costicola, Virgibacillus oceani, Virgibacillus marismortui, Marinobacter lipolyticus, Halobacillus karajensis, Salicola salis, Pseudoalteromonas shioyasakiensis, Salinicoccus amylolyticus, and Paracoccus salipaludis. Therefore, the present study highlights the diversity of the culturable halophilic bacteria in a Mediterranean solar saltern, harboring various valuable halotolerant enzymes.
... The use of microalgae as biomass has several advantages as they are more efficient in performing photosynthesis and grow more rapidly than land plants, they can grow in nonarable lands (not competing with edible biomasses) and are used in wastewaters remediation [22]. Furthermore, microalgal biomass may be used in pharmaceutical and cosmetic industries, thanks to its content of high-value bio compounds such as carotenoids, proteins and lipids [23,24]. ...
... The organisms that can thrive under high salinity conditions (>30% of NaCl concentrations) are known as halophiles. Such organisms can be found in three main domains: bacteria, archaea and eukarya and they can be found in hypersaline environments such as saline lakes (Menasria et al., 2018;Ruginescu et al., 2020;Villanova et al., 2021). ...
Extremophiles are magnificent living beings who thrive in extreme environmental
conditions. Many scientific studies focusing on identifying extremophiles, their
products, and their mechanisms have been recorded in the recent decades. Such
studies have mainly focused on extremophiles and the feasibility of using them in
various arenas including biofuel synthesis and agriculture. Extremophiles generate the
least harmful and biodegradable industrial waste in most cases and produce
consistent and higher yields under adverse conditions. Although, several whole-cell
extremophiles, extremolytes and extremozymes are currently being used for
industrial purposes, many more extremophiles, their products and mechanisms are
yet to be discovered. Furthermore, metagenomic studies and genetic engineering of
the desired extremozymes into mesophilic hosts and increasing their specificity using
nanotechnology would lead to more advanced discoveries. Finding novel
extremophiles and their products is expected to revolutionize a vast array of
industries. Accordingly, extremophiles are considered as tomorrow’s game changers
that drive the industrial world towards the development of a bio-based economy.
... In the case of metabolite products, some stresses are often applied to the cultivation to stimulate biomolecule production. Some examples of the employed stresses are high salinity and high light (Arena et al., 2021;Villanova et al., 2021), flashing light (Lima et al., 2020(Lima et al., , 2022 and nutrient deficiency (Solovchenko et al., 2008). ...
Microalgae and cyanobacteria are a precious source for the production of biofuels/bioenergy, biomaterials and valuable biochemicals. Beyond photosynthetic CO2 conversion, microalgal systems can involve the valorisation of waste streams and the implementation of green chemistry, industrial symbiosis, and circular bioeconomy approaches. However, their sustainability is uncertain, thus their large-scale application is hindered. The numerous life cycle assessments (LCAs) performed so far are mostly based on data extrapolated from lab-scale experiments or the literature, leading to qualitative and controversial results. This paper reviews primary data-based LCA studies on microalgal pilot to industrial-scale plants. Sixteen studies satisfied the selection criteria, despite they used primary data almost exclusively for cultivation and harvesting. The outlined current status (methodology, inventory, energy performance and environmental impacts) highlighted the lack of uniformity in the applied methods and the presentation of results, as well as some lack of transparency. Nevertheless, the review concluded that electricity consumption and infrastructure are major hotspots. Therefore, the use of renewable energy for supplying the process and of sunlight for biomass photosynthesis should be preferred. The upstream processes produce large impacts. Thus, a suitable reactor, geographic location, and harvesting method should be selected. Biofuels are not competitive in most cases, but some promising multi-product biorefinery scenarios have been presented. To improve the environmental profile of microalgal high-value compounds (e.g., astaxanthin or biostimulants), co-product valorisation, waste stream utilization, renewable energy deployment, and compound productivity should be enhanced. More efforts on LCA of large-scale plants are required, especially looking at integrated biorefinery concepts, to take a crucial step towards the implementation of sustainable commercial systems.
... cultivated under salt stress (Villanova et al., 2021a). The salinity in the tested RAS wastewater was only slightly higher than in the microalgae cultivation medium (Table 1). ...
The overall goal of this study was to provide solutions to innovative microalgae-based technology for wastewater remediation in a cold-water recirculating marine aquaculture system (RAS). This is based on the novel concept of integrated aquaculture systems in which fish nutrient-rich rearing water will be used for microalgae cultivation. The produced biomass can be used as fish feed, while the cleaned water can be reused, to create a highly eco-sustainable circular economy. Here, we tested three microalgae species Nannochloropis granulata (Ng), Phaeodactylum tricornutum (Pt), and Chlorella sp (Csp) for their ability to remove nitrogen and phosphate from the RAS wastewater and simultaneously produce high-value biomass, i.e., containing amino acids (AA), carotenoids, and polyunsaturated fatty acids (PUFAs). A high yield and value of biomass were achieved for all species in a two-phase cultivation strategy: i) a first phase using a medium optimized for best growth (f/2 14x, control); ii) a second “stress” phase using the RAS wastewater to enhance the production of high-value metabolites. Ng and Pt performed best in terms of biomass yield (i.e., 5-6 g of dry weight, DW.L⁻¹) and efficient cleaning of the RAS wastewater from nitrite, nitrate, and phosphate (i.e., 100% removal). Csp produced about 3 g L⁻¹ of DW and reduced efficiently only nitrate, and phosphate (i.e., about 76% and 100% removal, respectively). The biomass of all strains was rich in protein (30-40 % of DW) containing all the essential AA except Methionine. The biomass of all three species was also rich in PUFAs. Finally, all tested species are excellent sources of antioxidant carotenoids, including fucoxanthin (Pt), lutein (Ng and Csp) and β-carotene (Csp). All tested species in our novel two-phase cultivation strategy thus showed great potential to treat marine RAS wastewater and provide sustainable alternatives to animal and plant proteins with extra added values.
... Using mass spectrometry and genome analysis, Graupner et al. (2012) studied the characteristics of antifungal virulence factors in the pathogen Janthinobacterium agaricidamnosum, which causes soft rot in Agaricus bisporus. With the rapid development of molecular biotechnology, molecular markers have been widely used in the classification, identification, and genetic diversity analysis of fungi; this is also due to the fact that they are stable, can be used rapidly, and are low cost (Villanova et al., 2021). Notably, reports on pathogens that cause disease in Agaricus bisporus during postharvest storage are rare. ...
In this study, we developed oregano essential oil-mesoporous nano-silica (OEO-MSNPs), a new and safe eco-friendly antifungal system. MSNPs showed ordered mesoporous structures by TEM, which can provide space for loading OEO. The FTIR characterization of MSNPs and OEO-MSNPs showed that OEO was successfully embedded into the MSNPs. The loading rate of OEO-MSNPs to OEO reached about 60%, and OEO-MSNPs had better antifungal activity against the mold (Curvularia lunata MF380802.1) found in postharvest decayed Agaricus bisporus. The antifungal effects of OEO-MSNPs against Curvularia lunata MF380802.1 (C. lunata) were investigated. Then, our results showed that the antifungal effect of OEO-MSNPs had a minimum inhibitory concentration (MIC) and a minimum fungicidal concentration (MFC) at 0.20 mg/mL and 0.40 mg/mL, respectively. Furthermore, the integrity of cell membranes and nuclear membranes of C. lunata was destroyed during the interaction with OEO-MSNPs, resulting in the exudation of nucleic acids, proteins, and other substances in vitro. This work provides a theoretical basis for the development of effective treatments to address the infection of C. lunata during the storage and preservation of Agaricus bisporus. This newly developed method for encapsulating EOs in MSNPs has potential application in the design of effective antimicrobial materials.
... The reason for this choice is that microalgae harvested from an environment are already adapted to its solicitation and then more resistant when employed in industrial applications. This idea was already applied to Sicily for different applications [6][7][8]. ...
In this work, municipal wastewater was treated with microalgal/activated sludge consortia. We aimed at obtaining a positive interaction between the microalgae and the heterotrophic bacteria and identifying the best combination for bioremediation purposes. A strain of Chlorella sp CW2 employed in this work was isolated from AS and molecularly characterised in this work for the first time. This strain and another previously isolated strain (Chlorella sp Pozzillo) were inoculated alone and in combination with AS in different ratios in wastewaters. Microalgae/activated sludge growth curves were obtained by using a UV–vis spectrophotometer and a fluorimeter to distinguish the contribution of the photosynthetic microorganisms to the total growth. The effectiveness for the bioremediation of municipal wastewaters was evaluated by measuring the COD, the total nitrogen and total phosphorous content at the end of batch cultivations. Overall, the best abatement was achieved by the microalga Chlorella sp CW2 inoculated with activated sludge in the ratios 1:2 and 2:1, with a decrease of 81.39 % ± 0.56, 86.12 % ± 0.43, 82.89 % ± 2.66 and 82.5 % ± 0.83, 72.66 % ± 0,46, 97.15 % ± 0.44 of COD, total nitrogen and total phosphorous, respectively. Finally, the residual biomass, constituted by a sludge enriched in microalgae, was analysed for its content in carbohydrates, lipids and fatty acid in order to suggest the best application for its valorisation. Considering the final composition of the obtained biomass and its remediation potential, the most promising sample may be the microalga Chlorella sp CW2 inoculated with activated sludge in the ratio 1:5.
... Halophiles can be isolated from brackish or hypersaline environments and comprises organisms from genus like [135]. ...
Limits of life on earth is still an expanding topic and extensive research is being carried out throughout the world. These limits are the nether and higher boundaries of various parameters like atmospheric, geochemical, temperature and water/nutrient availability. By the means of evolution many microorganisms have evolved and adapted to harsh extreme conditions whose study can give us insight into their defense mechanisms and adaptive strategies. The secondary metabolites as well as enzymes which are stable over a broad range of conditions can be extracted and put forward for the betterment of the environment and humankind. This review focuses on extremophiles living in the extreme environmental conditions of temperature, radiation, desiccation, salinity and pH.
... To the best of the authors knowledge, this is the first time that a halophilic mixed culture consisting of these three halophilic genera (Oceanobacillus sp., Halomonas sp. and Aliifodinibius sp.) is described for the use in a biological RPB treatment process. The discovery and usage of novel isolated halophilic microorganisms and their exploitation in a biotechnological and industrial context was already successfully demonstrated (Guven et al., 2018;Rezaei Somee et al., 2018;Zare et al., 2019;Hasanzadeh et al., 2020;Villanova et al., 2021). Besides, the usage of a co-culture might be even beneficial for the present bioprocess. ...
Integrating bioprocess solutions for treatment and subsequent reuse of saline residual process brine into industrial processes could increase the sustainability of production chains. However, such bioprocesses require large-scales and a robust operation over a prolonged period. Consequently, the aim of this study was to analyze scale-up equivalence as well as continuous and stable process performance of a previously established lab scale process for the degradation of organic contaminants (formate and aromatic compounds) in an industrial context. To that end, a pilot-scale bubble column bioreactor system equipped with a membrane-based cell retention system for process intensification was integrated at an industrial production site. The process was successfully scaled-up and continuously operated for more than 210 days. Overall, the process proved to be robust towards changing compositions of the residual process brine stream and degradation rates for organic contaminants were close to 100%. Interestingly, due to the unsterile process conditions, the original Haloferax mediterranei culture was replaced by a novel halophilic bacterial community consisting of three bacterial genera. To further improve process economics and productivity, an optimization of the co-substrate feeding strategy for glycerol is required, as results indicated a potential correlation between glycerol feeding and formate degradation rates. To that end, decoupling of the glycerol feeding from the residual process brine feed is a potential way to increase process control options and allow for easy adaptation of the process to changing residual process brine compositions. Ultimately, the process described here could be a promising alternative for chemical or physical methods of treating residual process brine and once more underlines the potential to exploit natural microbial diversity for industrial purposes.
