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| Roles of actinomycete natural products in the leaf-cutter ant ecosystem. Different actinomycete species isolated from attine ant integument (Streptomyces spp., Pseudonocardia spp., etc.) secrete natural products with various functions and roles. (Top left) Streptomyces spp. confer ant immunity by producing valinomycin, antimycins, and actinomycins, which inhibit pathogens and parasites. (Top Right) Actinomycetes produce a range of antifungals including dentigerumycins, candicidin, and nystatin variants, which inhibit fungal pathogens (e.g., Escovopsis spp.) but are not detrimental to the attine ant fungal symbiont, L. gongylophorus. (Bottom Left) Pseudonocardia competing for residency on the ant integument use plasmid-encoded niche defense mechanisms by synthesizing 9-methoxyrebeccamycin. (Bottom Right) Natural products from actinomycetes help preserve the attine ant community, which in turn, affects the larger ecosystem. Leaf-cutter ants forage up to 17% of the foliar biomass and the L. gongylophorus symbiont helps degrade organic material, which collectively contributes to carbon turnover.
Source publication
Actinomycetes, filamentous actinobacteria found in numerous ecosystems around the globe, produce a wide range of clinically useful natural products (NP). In natural environments, actinomycetes live in dynamic communities where environmental cues and ecological interactions likely influence NP biosynthesis. Our current understating of these cues, an...
Contexts in source publication
Context 1
... of the most extensively characterized natural systems that harbor actinomycetes is that of the leaf-cutter ants. Actinobacteria associated with fungus-growing leaf-cutter ants produce NP that have been shown to have key roles in shaping this ecosystem (Figure 1) (Currie et al., 1999). Primarily found in the Americas, leaf-cutter ants (including the genera Atta and Acromyrmex) maintain a delicately balanced network that includes their fungal food source, Leucoagaricus gongylophorus, and actinomycetes, which produce antimicrobials to protect the fungal gardens against pathogen invasion ( Schultz and Brady, 2008;Hölldobler and Wilson, 2010;Andersen et al., 2015). ...
Context 2
... antagonism between different species of ant-associated Pseudonocardia was pronounced in more distantly related species, suggesting that competition between Pseudonocardia have shaped this association from its evolutionary origin (Poulsen et al., 2007). Consistent with this idea, Van Arnam et al. (2015) recently found that one Pseudonocardia strain produced a novel rebeccamycin analog that inhibited the growth of competing Pseudonocardia (Figure 1). PacBio sequencing of these strains revealed variations in the rebeccamycin BGCs which were located on plasmids, suggesting plasmid-encoded niche defense (Van Arnam et al., 2015). ...
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... the MALDI-imaging data clearly showed the localization of valinomycin secreted by Streptomyces on the ant cuticle at varying concentrations. Taken together, these data suggest that the presence of integumental biofilms and their secreted NP work in concert to protect fungal gardens from invading bacteria and fungi, while simultaneously contributing to worker ant immunity by inhibiting the growth of entomopathogens (Figure 1) (Schoenian et al., 2011). To corroborate the importance of actinomycete NP in their protective roles against ant-specific pathogens, cuticle-associated biofilms were removed with antibiotic treatment, thereby exposing the ants to attack by the entomopathogenic fungus M. anisopliae, which resulted in increased mortality of Acromyrmex ants ( Mattoso et al., 2012). ...
Context 4
... they are the dominant herbivores in much of the Neotropics ( Costa et al., 2008), the foraging activity of leaf- cutter ants has a large impact in the overall function of their ecosystems (Figures 1 and 2). These ants forage up to 17% of the foliar biomass and contribute substantially to carbon turnover in their forest habitats ( Costa et al., 2008). ...
Similar publications
Like all higher organisms, plants have evolved in the context of a microbial world, shaping both their evolution and their contemporary ecology. Interactions between plant roots and soil microorganisms are critical for plant fitness in natural environments. Given this co-evolution and the pivotal importance of plant-microbial interactions, it has b...
Citations
... They produce more than 70% of bioactive actives with diverse biological activities used in human therapy and other industrially important secondary metabolites [7]. They possess the genetic capacity to produce various kinds of compounds that were never detected in laboratory conditions (Behie et al. 2017). In addition, Streptomyces is one of the most important in the Actinomycetales. ...
Introduction
The emergence of multidrug-resistant bacteria and biofilms requires discovering new antimicrobial agents from unexplored environments.
Objectives
This study aims to isolate and characterize a new actinobacterial strain from the Hoggar Mountains in southern Algeria and evaluate its ability to produce bioactive molecules with potential antibacterial and antibiofilm activities.
Methods
A novel halotolerant actinobacterial strain, designated HG-17, was isolated from the Hoggar Mountains, and identified based on phenotypic characterizations, 16S rDNA sequence analysis, and phylogenetic analysis. The antibacterial and antibiofilm activities of the strain were assessed, and the presence of biosynthetic genes (PKS-I and NRPS) was confirmed. Two active compounds, HG-7 and HG-9, were extracted butanol solvent, purified by HPLC, and their chemical structures were elucidated using ESI mass spectrometry and NMR spectroscopy.
Results
The strain HG-17 was identified as Streptomyces purpureus NBRC with 98.8% similarity. It exhibited strong activity against multidrug-resistant and biofilm-forming bacteria. The two purified active compounds, HG-7 and HG-9, were identified as cyclo-(d-cis-hydroxyproline-l-phenylalanine) and cyclo-(l-prolone-l-tyrosine), respectively. The minimum inhibitory concentrations (MICs) of HG-7 and HG-9 ranged from 3 to 15 μg/mL, comparable to the MICs of tetracycline (8 to 15 μg/mL). Their minimum biofilm inhibitory concentration (MBIC 50%) showed good inhibition from 48.0 to 52.0% at concentrations of 1 to 7 μg/mL against the tested bacteria.
Conclusion
This is the first report of cyclo-(d-cis-hydroxyproline-l-phenylalanine) and cyclo-(l-prolone-l-tyrosine) antibiotics from S. purpureus and their anti-multi-drug-resistant and biofilm-forming bacteria. These results indicate that both antibiotics could be used as effective therapeutics to control infections associated with multidrug-resistant bacteria.
... The important role of marine natural products in drug discovery from marine microorganisms, algae, sponges, bryozoans, mollusks, etc., has been well-recognized and highlighted in various documents [12][13][14]. Among the sources of marine-derived natural products, marine-derived actinomycetes have long been prolific chemical synthesizers, providing a great variety of biologically active molecules with unprecedented skeletal structures [15]. When structurally novel compounds possess proton-deficient structures, the elucidation of their structures is more challenging than the analogues of previously reported molecules. ...
Two new proton-deficient metabolites, tandocyclinones A and B (1 and 2), were discovered via the chemical profiling of the Streptomyces sp. strain TDH03, which was isolated from a marine sediment sample collected from the intertidal mudflat in Tando Port, the Republic of Korea. The structures of 1 and 2 were elucidated as new ether-bridged C-glycosyl benz[a]anthracenes by using a combination of spectroscopic analyses of ultraviolet (UV) and mass spectrometry (MS) data, along with nuclear magnetic resonance (NMR) spectra, which were acquired in tetrahydrofuran (THF)-d8 selected after an extensive search for a solvent, resulting in mostly observable exchangeable protons in the 1H NMR spectrum. Their configurations were successfully assigned by applying a J-based configuration analysis, rotating-frame Overhauser enhancement spectroscopy (ROESY) NMR correlations, chemical derivatization methods based on NMR (a modified version of Mosher’s method) and circular dichroism (CD) (Snatzke’s method using Mo2(OAc)4-induced CD), as well as quantum-mechanics-based computational methods, to calculate the electronic circular dichroism (ECD). Tandocyclinones A and B (1 and 2) were found to have weak antifungal activity against Trichophyton mentagrophytes IFM40996 with an MIC value of 128 μg/mL (244 and 265 μM for 1 and 2, respectively). A further biological evaluation revealed that tandocyclinone A (1) displayed inhibitory activity against Mycobacterium avium (MIC50 = 40.8 μM) and antiproliferative activity against SNU638 and HCT116 cancer cells, with IC50 values of 31.9 µM and 49.4 µM, respectively.
... Actinomycetes support the ecology due to their environmentally favourable nature. They have been recognized to generate a range of antibiotics, biocontrol agents, and compounds that encourage plant growth (52)(53)(54)(55). Actinomycetes enhance the soil fertility and production of the plant and also increase the nitrogen level (15). ...
Research on the natural resources found in medicinal plants and endophytes makes important contributions to a wide variety of fields, including drug development, agribusiness, biotechnology, and sustainable development. Endophytes are a group of microorganisms that can be discovered in the rhizosphere of plants being used in medical treatment. These microorganisms have the capability of producing a wide range of primary and secondary metabolites by utilizing a variety of distinct biosynthetic pathways. Several different technologies, such as genetic modification and artificial intelligence (AI), play a significant role in the acceleration of endophytic research. These methods aid in the discovery and synthesis of novel compounds with medicinal promise, the predictive analysis of bioactive compounds, the identification and classification of endophytes, and the optimization of potential bioactive compounds. In light of this, the current review focuses on providing a concise comprehension of the influence of bioactive compounds secreted by specific endophytes on medicinal plants through the application of significant technologies in the field of endophytic research.
... previously isolated from marine sponges and octocorals demonstrated bioactivity against both coral and human pathogens and were shown to possess biosynthetic pathways (e.g., non-ribosomal peptide synthetases) involved in the production of natural products (Palomo et al. 2012;Monti et al. 2022). Other bacterial genera within the phyla Actinobacteria and Proteobacteria exhibiting high betweenness centrality values in both E. flexuosa and A. americana networks are known to synthesize antimicrobial compounds and/or molecules which can interfere with quorum sensing signals, thereby influencing the abundance of other host-associated prokaryotes and/or opportunistic pathogens (Bérdy 2005;Behie et al. 2017;Raimundo et al. 2018;Rajasabapathy et al. 2020;Siro et al. 2022). ...
Unlabelled:
Despite the current decline of scleractinian coral populations, octocorals are thriving on reefs in the Caribbean Sea and western North Atlantic Ocean. These cnidarians are holobiont entities, interacting with a diverse array of microorganisms. Few studies have investigated the spatial and temporal stability of the bacterial communities associated with octocoral species and information regarding the co-occurrence and potential interactions between specific members of these bacterial communities remain sparse. To address this knowledge gap, this study investigated the stability of the bacterial assemblages associated with two common Caribbean octocoral species, Eunicea flexuosa and Antillogorgia americana, across time and geographical locations and performed network analyses to investigate potential bacterial interactions. Results demonstrated that general inferences regarding the spatial and temporal stability of octocoral-associated bacterial communities should not be made, as host-specific characteristics may influence these factors. In addition, network analyses revealed differences in the complexity of the interactions between bacteria among the octocoral species analyzed, while highlighting the presence of genera known to produce bioactive secondary metabolites in both octocorals that may play fundamental roles in structuring the octocoral-associated bacteriome.
Supplementary information:
The online version contains supplementary material available at 10.1007/s13199-023-00923-x.
... These are widely spread in soil and are involved in dead organic matter decomposition, nitrogen fixation, and phosphate solubilization. Actinomycetes can produce antibiotics, biocontrol agents, and plant growth-promoting substances (Behie et al. 2017). Actinomycetes conquer the pathogens such as Pythium ultimum and Erwinia carotovora, causing damping-off and post-harvest rot diseases, respectively, in plants ( AbdElgawad et al. 2020). ...
The global increase in the frequency of climatic extremes exposed the plants to various abiotic stresses. Assuring food as well as nutritional security of the increasing climate change-induced abiotic stress turned out to be a major challenge for the sustainability of crop production in the current era. To cope with this situation, researchers have already recommended many climate-smart strategies. However, these alternatives are sometimes technically complex, costly, and nonrenewable. Therefore, there is an urgent requirement to move into an ecologically friendly, cost-effective, and sustainably appropriate alternative in the current situation of climate change. It was well-established recently that microbes can be considered in agriculture as environmentally friendly and cost-effective biotechnological resources. Microorganisms are unraveling their unique properties in recent times for the mitigation of the negative effects of abiotic stresses on crops. In this chapter, the prospects of the most prominent beneficial microorganisms (viz., plant growth-promoting rhizobacteria, mycorrhizal fungi, actinomycetes, and cyanobacteria) in terms of their innate stress-tolerant mechanisms such as biosynthesis of phytohormones, ion homeostasis, induction and accumulation of osmoprotectants, nutrient uptake enhancement, and antioxidant mechanisms have been discussed elaborately to understand the potential of soil microorganisms in imparting plant stress tolerance.KeywordsAbiotic stressesBeneficial microorganismsRhizosphereStress tolerance
... Actinomycetes memproduksi senyawa antimikroba yang mampu menghambat bakteri yang bersifat Gram positif ataupun Gram negatif dengan persentase sebesar 75% [24]. Selain itu, senyawa metabolit lain yang dapat dihasilkan oleh bakteri Actinomycetes melalui proses fermentasi yaitu staurosporin, diastaphenazine, 3-acetonylidene-7prenylindolin-2-1 dan antimycin [26]. Mekanisme kerja antimikroba yang berasal dari senyawa metabolit sekunder ini yaitu dapat menghambat sintesis protein bakteri [27]. ...
Actinomycetes merupakan bakteri Gram positif, berbentuk batang panjang, dan dapat dimanfaatkan sebagai antimikroba karena dapat memproduksi senyawa metabolit sekunder. Faktor yang mempengaruhi produksi senyawa tersebut adalah waktu fermentasi dan pH. Salmonella typhi merupakan bakteri patogen yang menimbulkan penyakit demam tifoid. Penelitian ini bertujuan untuk mengetahui lama optimasi fermentasi isolat Actinomycetes dengan kontrol pH terhadap pertumbuhan bakteri S. typhi secara In Vitro. Jenis dan desain penelitian yang digunakan adalah studi true experimental dan Rancangan Acak Lengkap (RAL). Media Starch Casein Agar (SCA) digunakan untuk membiakkan Isolat Actinomycetes lalu melakukan fermentasi pada media yang mengandung mannitol 2%, pepton 2%, dan glukosa 1% serta diinkubasi selama 1, 2 dan 3 hari. Metode uji aktivitas antimikroba menggunakan metode sumuran pada media Nutrient Agar (NA). Bakteri Actinomycetes dengan lama fermentasi 1, 2 dan 3 hari disertai dengan kontrol pH mampu menghambat pertumbuhan bakteri S.typhi dengan rata-rata zona hambat yang terbentuk yaitu 13,70 mm; 15,41 mm dan 15,09 mm. Uji Kruskal Wallis menunjukkan adanya perbedaan yang bermakna terhadap zona hambat pada tiap kelompok perlakuan. Kelompok fermentasi hari ke-2 memiliki efektivitas antimikroba terbesar dengan nilai rata-rata zona hambat sebesar 15,41 mm. Mekanisme aktivitas antimikroba meliputi menghambat sintesis protein, menghambat dinding sel maupun menghambat sintesis DNA bakteri. Kata kunci: Actinomycetes; antimikroba; kontrol pH; lama fermentasi; Salmonella typhi
... Changes in the abundances of taxa in the poplar root microbiome may also indicate differences in microbial fitness under different biotic and abiotic conditions. Many of these compounds are induced in response to specific environmental cues (Behie et al., 2017). We postulate that the overproduction of specific metabolites within plant roots leads to exudation of the over-produced metabolite into the rhizosphere and apoplast, where it can foster the growth of specific microbial taxa (Badri et al., 2013;Balmer et al., 2013;Bai et al., 2014). ...
Root microbiota composition shifts during the development of most annual plants. Although some perennial plants can live for centuries, the host–microbiome partnerships and interaction mechanisms underlying their longevity remain unclear.
To address this gap, we investigated age‐related changes in the root metabolites, transcriptomes, and microbiome compositions of 1‐ to 35‐yr‐old Populus tomentosa trees.
Ten co‐response clusters were obtained according to their accumulation patterns, and members of each cluster displayed a uniform and clear pattern of abundance. Multi‐omics network analysis demonstrated that the increased abundance of Actinobacteria with tree age was strongly associated with the flavonoid biosynthesis. Using genetic approaches, we demonstrate that the flavonoid biosynthesis regulator gene Transparent Testa 8 is associated with the recruitment of flavonoid‐associated Actinobacteria. Further inoculation experiments of Actinobacteria isolates indicated that their colonization could significantly improve the host's phenotype. Site‐directed mutagenesis revealed that the hyBl gene cluster, involved in biosynthesis of an aminocyclitol hygromycin B analog in Streptomyces isolate bj1, is associated with disease suppression.
We hypothesize that interactions between perennial plants and soil microorganisms lead to gradual enrichment of a subset of microorganisms that may harbor a wealth of currently unknown functional traits.
... Actinobacteria are known to produce 70% of the antibiotics used today. 40,41 Screening have been carried out to obtain isolates that produce antivibrio compounds. Actinobacteria mainly Streptomyces spp. ...
Vibriosis causes serious problems and economic loss in aquaculture and human health. Investigating natural products as antivibrio agents has gained more attention to combat vibriosis. The present review highlights the chemical diversity of antivibrio isolated from bacteria, fungi, plants, and marine organisms. Based on the study covering the literature from 1985-2021, the chemical diversity ranges from alkaloids, terpenoids, polyketides, sterols, and peptides. The mechanisms of action are included inhibiting growth, interfering with biofilm formation, and disrupting of quorum sensing. Relevant summaries focusing on the source organisms and the associated bioactivity of different chemical classes are also provided. Further research on in vivo studies, toxicity, and clinical is required for the application in aquaculture and human health.
... Phylum Actinobacteria has been known as the most diverse bacterial group in nature and includes the genus of Streptomyces can be isolated from many different environments (Worsley et al., 2020). These Gram-positive bacteria have a high GC content and show a remarkable range of morphologies (Behie et al., 2017). The genus has also represented numerous functional secondary metabolites, and nearly 17% of the metabolites have biological activities (Harir et al., 2018). ...
... The genus has also represented numerous functional secondary metabolites, and nearly 17% of the metabolites have biological activities (Harir et al., 2018). Notably, Actinobacteria produce two-thirds of all known antibiotics used in the clinic today, but also a vast array of anticancer, immunosuppressants, anthelmintics, herbicides, and antiviral compounds in addition to extracellular enzymes (Behie et al., 2017). Streptomycetes is a core group in agro-ecosystems and can improve plant health and migrate from the rhizosphere to the endosphere (Kim et al., 2019a). ...
Plant microbiota has influenced plant growth and physiology significantly. Plant and plant-associated microbes have flexible interactions that respond to changes in environmental conditions. These interactions can be adjusted to suit the requirements of the microbial community or the host physiology. In addition, it can be modified to suit microbiota structure or fixed by the host condition. However, no technology is realized yet to control mechanically manipulated plant microbiota structure. Here, we review step-by-step plant-associated microbial partnership from plant growth-promoting rhizobacteria to the microbiota structural modulation. Glutamic acid enriched the population of Streptomyces, a specific taxon in anthosphere microbiota community. Additionally, the population density of the microbes in the rhizosphere was also a positive response to glutamic acid treatment. Although many types of research are conducted on the structural revealing of plant microbiota, these concepts need to be further understood as to how the plant microbiota clusters are controlled or modulated at the community level. This review suggests that the intrinsic level of glutamic acid in planta is associated with the microbiota composition that the external supply of the biostimulant can modulate.
... A variety of natural compounds secreted by actinomycetes that live in the rhizosphere have been proven to aid in plant defense against pathogenic bacteria and fungi (Rungin et al., 2012;Suárez-Moreno et al., 2019). In addition, biogeographic studies on Streptomyces ecology have proposed that niches dominated by Streptomyces species with broad and extremely effective inhibitory phenotypes may act as competitive hot spots, implicating the Streptomyces as critical for sustaining plant health (Behie et al., 2017). As a result, all isolates in the current study were initially screened for antimicrobial property against an important plant pathogen using the coculture technique. ...
Phytophthora is an important, highly destructive pathogen of many plants, which causes considerable crop loss, especially durians in Thailand. In this study, we selectively isolated Streptomyces from the rhizosphere soil with a potent anti-oomycete activity against Phytophthora palmivora CbP03. Two strains (SNN087 and SNN289) demonstrated exceptional plant growth-promoting properties in pot experiment. Both strains promoted mung bean ( Vigna radiate ) growth effectively in both sterile and non-sterile soils. Metagenomic analysis revealed that Streptomyces sp. SNN289 may modify the rhizosphere microbial communities, especially promoting microbes beneficial for plant growth. The relative abundance of bacterial genera Bacillus , Sphingomonas , Arthrobacter , and Pseudarthrobacter , and fungal genera Coprinellus and Chaetomium were noticeably increased, whereas a genus Fusarium was slightly reduced. Interestingly, Streptomyces sp. SNN289 exhibited an exploratory growth, which allows it to survive in a highly competitive environment. Based on whole genome sequence analysis combined with an ANI and dDDH values, this strain should be classifiable as a new species. Functional annotation was also used to characterize plant-beneficial genes in SNN087 and SNN289 genomes for production of siderophores, 3-indole acetic acid (IAA), ammonia, and solubilized phosphate. AntiSMASH genome analysis and preliminary annotation revealed biosynthetic gene clusters with possible secondary metabolites. These findings emphasize the potential for application of strain SNN289 as a bioinoculant for sustainable agricultural practice.
