Spatial Physiochemical and Metagenomic Analysis of Desert Environment.

Investigating the bacterial diversity and their metabolic capabilities are crucial for interpreting ecological patterns in desert environment, and assessing the presence of exploitable microbial resources. In this study, we evaluated the spatial heterogeneity of physico-chemical parameters, soil bacterial diversity and metabolic adaptation at meter scale. Soil samples were collected from two quadrates a desert environment (Thar Desert, India) which face hot arid climate with very little rainfall and extreme temperatures. Analysis of physico-chemical parameters and subsequent variance analysis (p-values < 0.05) revealed that sulfate, potassium and magnesium ions were the most variable between the quadrates. Microbial diversity of the two quadrates was studied using Illumina bar coded sequencing by targeting V3-V4 regions of 16S rDNA. As the results, 702504 high-quality sequence reads, assigned to 173 operationaltaxonomic units (OTUs) at species level. The most abundant phyla in both quadrates were Actinobacteria (38.72%), Proteobacteria (32.94%), and Acidobacteria (9.24%). At genus level, Gaiellarepresented highest prevalence, followed by Streptomyces, Solirubrobacter, Aciditerrimonas, Geminicoccus, Geodermatophilus, Microvirga, and Rubrobacter. Between the quadrates, significant difference (p-values < 0.05) was found in the abundance of Aciditerrimonas, Geodermatophilus Geminicoccus, Ilumatobacter, Marmoricola, Nakamurella and Solirubrobacter. Metabolic functional mapping revealed diverse biological activities, and was significantly correlated with physico-chemical parameters. The results revealed spatial variation of ions, microbial abundance and functional attributes in the studied quadrates, and patchy nature in local scale. Interestingly, abundance ofthe biotechnologically important phylum Actinobacteria, with large proposition of unclassified speciesin the desert suggested that this arid environment is the promising site for bioprospection.

Biosynthetic Potential of Bioactive Streptomycetes Isolated From Arid Region of the Thar Desert, Rajasthan (India).

Acquisition of Actinobacteria, especially Streptomyces from previously underexplored habitats and the exploration of their biosynthetic potential have gained much attention in the rejuvenated antibiotics search programs. Herein, we isolated some Streptomyces strains, from an arid region of the Great Indian Thar Desert, which possess an ability to produce novel bioactive compounds. Twenty-one morphologically distinctive strains differing in their aerial and substrate mycelium were isolated by employing a stamping method. Among them, 12 strains were identified by a two-level antimicrobial screening method, exerting antimicrobial effects against a panel of indicator strains including methicillin-resistant Staphylococcus aureus and vancomycin-resistant Enterococcus species. Based on their potent antimicrobial activity, four isolates were further explored by 16S rRNA gene-based identification, genetic screening, and metabolomic analysis; and it was found that these strains belong to the genus Streptomyces. The selected strains were found to have polyketide synthase and non-ribosomal peptide synthetase systems. In addition, extracellular metabolomic screening revealed that the isolates produced analogs of doxorubicinol, pyrromycin, erythromycin, and 6-13 other putative novel metabolites. These results demonstrate the significance of Streptomyces inhabiting the arid region of Thar Desert, suggesting that similar arid environments can be considered as the reservoirs of novel Streptomyces strains that could have biotechnological significance.