Diversity Of Streptomyces Research Articles

Culturable Streptomyces spp. from high-altitude, oligotrophic North Western Himalaya: a comprehensive study on the diversity, bioactivity and insights into the proteome of potential species.

The increasing global concern of antimicrobial resistance and shortage of new antimicrobials necessitates exploring untapped terrestrial environments for new bioactive microbiome diversity. The low-temperature and oligotrophic North Western Himalaya (NWH) region has a vast diversity of Streptomyces with potential antimicrobial properties that remain largely unexplored. This study evaluates the diversity of culturable Streptomyces from high-altitude NWH and their potential as a source of new antimicrobials through genus-specific isolation and identification. The results demonstrate a distinct phylogenetic clustering of Streptomyces from different sampling regions of NWH, site-specific variation in culturable β-diversity and species commonness with varying intersite bioactivity among different sites. Further, the study optimized the media selection for large-scale culture cultivation in antibiotic production processes and demonstrated the antimicrobial efficacy of Streptomyces against a range of pathogens through in vitro bioassays using minimum inhibitory concentration determination and antibiofilm activity. Untargeted label-free proteomic profiling also revealed variable expression of stress-response proteins and antibiotic regulators as a competitive survival strategy for selective antagonistic Streptomyces. The findings highlight the potential of NWH in augmenting antimicrobial discovery and combating antimicrobial resistance through the isolation and study of novel bioactive Streptomyces.

Streptomyces Diversity Maps Reveal Distinct High-Specificity Biogeographical and Environmental Patterns Compared to the Overall Bacterial Diversity.

Despite their enormous impact on the environment and humans, the distribution and variety of the biggest natural secondary metabolite producers, the genus Streptomyces, have not been adequately investigated. We developed representative maps from public EMP 16S rRNA amplicon sequences microbiomics data. Streptomyces ASVs were extracted from the EMP overall bacterial community, demonstrating Streptomyces diversity and identifying crucial diversity patterns. Our findings revealed that while the EMP primarily distinguished bacterial communities as host-associated or free-living (EMPO level 1), the Streptomyces community showed no significant difference but exhibited distinctions between categories in EMPO level 2 (animal, plant, non-saline, and saline). Multiple linear regression analysis demonstrated that pH, temperature, and salinity significantly predicted Streptomyces richness, with richness decreasing as these factors increased. However, latitude and longitude do not predict Streptomyces richness. Our Streptomyces maps revealed that additional samplings in Africa and Southeast Asia are needed. Additionally, our findings indicated that a greater number of samples did not always result in greater Streptomyces richness; future surveys may not necessitate extensive sampling from a single location. Broader sampling, rather than local/regional sampling, may be more critical in answering microbial biogeograph questions. Lastly, using 16S rRNA gene sequencing data has some limitations, which should be interpreted cautiously.

Diversity Analysis and Biocontrol Potential of Cultivatable Terrestrial Bacterial Streptomyces in Southern China

Streptomyces are filamentous bacteria that are extensively present in soil, play an important role in carbon cycling, and produce a large number of highly valuable secondary metabolites. In this study, total number of 411 isolates of Streptomyces were collected from ecologically similar habitats from 13 provinces in Southern China. They were clustered into 96 operational taxonomic units including eight potentially new species based on their 16S rDNA sequences. Phylogenetic analysis disclosed that the isolates with similar geographical distributions clustered together. Beta diversity of Streptomyces showed it manifests in a latitudinal diversity gradient (R2 = 0.3828, p = 0.0113). The beta diversity did not change significantly with geographic distance, and this could be due to the large longitudinal and relatively smaller latitudinal sampling range, as the phylogenetic clustering of regions with higher annual average temperature was analyzed with the nearest taxon index (R = −0.23, p = 0.045). Result of the Streptomyces biogeography evaluation shows the diversity of the genus is controlled by many of the same processes. Bioassay results disclosed that there were 27 isolates strongly antagonistic to plant pathogenic fungi and 71 isolates with strong nematocidal activity against pine wood nematode. Our results provide significant insights into the diversity and biocontrol potential of cultivatable Streptomyces in Southern China.

Genetic diversity and antifungal activities of the genera Streptomyces and Nocardiopsis inhabiting agricultural fields of Tamil Nadu, India

Actinomycetes receives much attention as plant-beneficial bacteria due to their distinct morpho-physiological, plant growth promoting and antifungal properties. Among the actinomycetes, members of the genus Streptomyces are of specific interest due to their metabolic versatility and ubiquity. The diversity of Streptomyces in different crop fields of Tamil Nadu has not been explored early. In this study, we explored phylogenetic diversity, morphological heterogeneity, and antifungal properties of cultivable actinomycetes isolated from the rhizosphere and bulk soils of different crops collected from 20 distinct districts of Tamil Nadu. A total of 65 actinomycetes were isolated from 40 soil samples including rhizosphere and bulk soils of different crops, and their diversity was analyzed using the 16S rRNA gene sequence. They were then characterized for cultural characteristics and antifungal activity against four fungal strains Fusarium udum, Fusarium oxysporum f.sp. ciceri, Macrophomina phaseolina and Sclerotium rolfsii. Out of the 65 isolates sequenced, 45 were found to be closely related to Streptomyces spp. while the remaining 20 showed similarities with Nocardiopsis spp. Cultural characterization on four different ISP media showed immense diversity among the members of the genera Streptomyces and Nocardiopsis. The strains of Streptomyces spp. and Nocardiopsis spp. showed varying levels of antifungal activity with all strains found antagonistic against both Fusarium udum and Fusarium oxysporum f.sp. ciceris. All the strains obtained in this study have been accessioned at the National Agriculturally Important Microbial Culture Collection (NAIMCC) to increase the database of characterized strains belonging to these two genera in the collection.

Towards quantifying microbial dispersal in the environment.

Towards quantifying microbial dispersal in the environment.

Molecular and biological characteristics of streptomyces diversity in the soils of the Saxaul forest in Mongolia

Saxaul (Haloxylon ammodendron) is a plant with a wide ecological range that forms forests in Mongolia often used as pastures for camels. Actinomycetes were isolated from the soils of the saxaul forest using selective isolation methods. According to the results of phylogenetic analysis based on the sequences of the 16S rRNA gene fragment, it has been established that the obtained isolates belong to the Streptomyces genus. According to the taxonomic position, strains (M41; M42; M 43; C 4-46; C 4-47; C 4-50; M44; C 5-54; C5-60 and C 5-63) demonstrate a high level of similarity (99.20- 100 %) of 16S rRNA gene sequences with type strains of the following species: S. fradiae, S. huasconensis, S. coeruleoprunus, S. tendae, S. rubrogriseus, S. malachitofuscus, S. flavoviridis S. pilosus, S. caelestis, S. azureus, S. fulvissimus, S. microflavus, S. griseussubsp. griseus, S. anulatus, S. cyaneofuscatus, S. luridiscabiei, S. halstedii, S. fulvorobeus, S. pratensis, S. setonii, S. anulatus, S. pratensis, S. caelestis and S. azureus.

The biogeography of Streptomyces in New Zealand enabled by high-throughput sequencing of genus-specific rpoB amplicons.

We evaluated Streptomyces biogeography in soils along a 1200 km latitudinal transect across New Zealand (NZ). Streptomyces diversity was examined using high-throughput sequencing of rpoB amplicons generated with a Streptomyces specific primer set. We detected 1287 Streptomyces rpoB operational taxonomic units (OTUs) with 159 ± 92 (average ± SD) rpoB OTUs per site. Only 12% (n = 149) of these OTUs matched rpoB sequences from cultured specimens (99% nucleotide identity cutoff). Streptomyces phylogenetic diversity (Faith's PD) was correlated with soil pH, mean annual temperature and plant community richness (Spearman's r: 0.77, 0.64 and -0.79, respectively; P < 0.05), but not with latitude. In addition, soil pH and plant community richness both explained significant variation in Streptomyces beta diversity. Streptomyces communities exhibited both high dissimilarity and strong dominance of one or a few species at each site. Taken together, these results suggest that dispersal limitation due to competitive interactions limits the colonization success of spores that relocate to new sites. Cultivated Streptomyces isolates represent a major source of clinically useful antibiotics, but only a small fraction of extant diversity within the genus have been identified and most species of Streptomyces have yet to be described.

Analysis of diversity of actinomycetes from arid and saline soils at Rajasthan, India

Actinomycetes are ubiquitous microbes with a variety of applications in industry and medicine. It is well known that different ecosystems harbour unique microbial populations, that is, bacterial diversity can be influenced by geography and ecology. Diversity studies of actinomycetes from extreme habitats in Rajasthan state of India was carried out in this study. The Sambhar salt lake and arid regions (sand dunes in Thar Desert and stone quarries) were mainly studied to understand the prevalence of halotolerant and xerotolerant actinomycetes. Isolation was done on selective media followed by morphological studies, estimation of diversity and 16S rDNA gene sequencing. All the samples had both streptomycete and non-streptomycete populations and the dominance values for sand dunes and salt lake ranged from 0.14 to 0.36 which indicate even spread or equal dominance of taxa. For taxon specific communities, the dominance values range from 0.13 to 0.43 confirming the existence of Streptomyces diversity. Actinomycetes represented nearly 77% of the culturable bacterial population in Sambhar salt Lake which could be due to their ability to survive in conditions of stress and adapt to the extremes in the environment. 16S rRNA gene sequences of few isolates from Rajasthan exhibited resemblance to isolates from geographically distant Sahara Desert (Tunisian section). 16S rRNA gene sequences suggest the isolates obtained from the Thar Desert and salt lake could be novel strains.

Taxonomic and functional diversity ofStreptomycesin a forest soil

In this work we report the isolation and the characterization of 79 Streptomyces isolates from a French forest soil. The 16S rRNA gene phylogeny indicated that a great diversity of Streptomyces was present in this soil, with at least nine different and potentially new species. Growth plate assays showed that most Streptomyces lineages exhibit cellulolytic and hemicellulolytic capacities and potentially participate in wood decomposition. Molecular screening for a specific hydrogenase also indicated a widespread potential for atmospheric H2 uptake. Co-culture experiments with representative strains showed antagonistic effects between Streptomyces of the same population and between Streptomyces and various fungi. Interestingly, in certain conditions, growth promotion of some fungi also occurred. We conclude that in forest soil, Streptomyces populations exhibit many important functions involved in different biogeochemical cycles and also influence the structure of soil microbial communities.

Presence and Diversity of Streptomyces in Dendroctonus and Sympatric Bark Beetle Galleries Across North America

Recent studies have revealed several examples of intimate associations between insects and Actinobacteria, including the Southern Pine Beetle Dendroctonus frontalis and the Spruce Beetle Dendroctonus rufipennis. Here, we surveyed Streptomyces Actinobacteria co-occurring with 10 species of Dendroctonus bark beetles across the United States, using both phylogenetic and community ecology approaches. From these 10 species, and 19 other scolytine beetles that occur in the same trees, we obtained 154 Streptomyces-like isolates and generated 16S sequences from 134 of those. Confirmed 16S sequences of Streptomyces were binned into 36 distinct strains using a threshold of 0.2% sequence divergence. The 16S rDNA phylogeny of all isolates does not correlate with the distribution of strains among beetle species, localities, or parts of the beetles or their galleries. However, we identified three Streptomyces strains occurring repeatedly on Dendroctonus beetles and in their galleries. Identity of these isolates was corroborated using a house-keeping gene sequence (efTu). These strains are not confined to a certain species of beetle, locality, or part of the beetle or their galleries. However, their role as residents in the woodboring insect niche is supported by the repeated association of their 16S and efTu from across the continent, and also having been reported in studies of other subcortical insects.

Comparison of Streptomyces diversity between agricultural and non-agricultural soils by using various culture media.

Streptomycetes play a key role in the sustainability of agriculture and indicates the level of health of soil, especially when considering the richness of them that are involved in biological control of soil borne diseases. 20 different soil samples were taken from agricultural (7) and non-agricultural places (13) and populations of streptomycetes were quantified in order to select the general culture media that had better reflect the changes of these bacteria. The most efficient medium for the isolation of Streptomyces was starch casein agar by the addition of nystatin. Pretreatment of soil samples with CaCO3 (1%) increased the streptomycetes occurring on the isolation plates. To establish a correlation with soil physico-chemical parameters, such as pH, salt, N, P, K, Na, Fe, Zn and Cu were also determined, most of the correlations being significantly positive on the quantification of Streptomyces diversity. Streptomycete counts ranged from a high of 6.7 x 10 6 to a low of 2.3 x 10 6 cfu/g dry soil of non-agricultural soils. Streptomycetes constituted 4.8 to 45.8% of the total culturable bacterial community. Higher streptomycete densities were greatest in non-agricultural soils with an average of 14.0% compared to agricultural soils with average of 10.1%. These results suggest that these bacteria may be represent an unexplored resource for pharmaceutical drug discovery but also may provide additional disease control in agriculture.

Chemical screening: A simple approach to visualizing Streptomyces diversity for drug discovery and further research

The morphological and biochemical characteristics of Streptomyces species tend to be very similar, and thus the elucidation of their diversity is both time- and money-consuming. Here we evaluated various streptomycetes isolates using a chemical screening approach in order to establish their secondary metabolite patterns, thereby avoiding the possible discounting of morphologically similar strains. Results demonstrated that each isolate presented a unique pattern of secondary metabolites independently of their morphological and biochemical characteristics. We also established the enormous diversity in metabolic products among our isolates, and thus many potentially new metabolites may be studied in further research. Our results indicate that chemical screening is a simple selection method for recognizing the specific fingerprint of each isolate, highlighting the particular metabolic characteristics of each with respect to the other studied strains.