Untapped bacterial diversity and metabolic potential within Unkeshwar hot springs, India

• Published in: Archives of microbiology Vol. 200; no. 5; pp. 753 - 770
• Main Authors: Mehetre, Gajanan, Shah, Manan, Dastager, Syed G., Dharne, Mahesh S.
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 01-07-2018; Springer Nature B.V
• Subjects: Arsenic; Bacteria; Biochemistry; Biodegradation; Biomedical and Life Sciences; Bioprospecting; Biotechnology; Carbohydrates; Cell Biology; Cell culture; Cellulase; Chromium; Cultivation; Culture media; Ecology; Heavy metals; Hot springs; Life Sciences; Metabolic pathways; Metabolism; Metabolites; Microbial Ecology; Microbiology; Microorganisms; Original Paper; Phylogeny; rRNA 16S; Secondary metabolites; Utilities; Water analysis; Water sampling; Water springs; Xylanase; India; Untapped; Bioprospecting; Bacterial diversity; Cultivation; Heavy metals
• ISSN: 0302-8933; 1432-072X
• DOI: 10.1007/s00203-018-1484-4

Hot springs support diverse and interesting groups of microorganisms adapted to extreme conditions and gaining attention in biotechnological applications. However, due to limitations of cultivation methods, a majority of such extremophiles remain uncultivated and unexplored. The advent of multiple cultivation conditions and specialized culture media could possibly aid to access the unexplored microbial portion of hot springs. In the present study, different media and isolation strategies were applied to isolate hitherto unexplored bacterial taxa in the water samples collected from Unkeshwar hot springs, India. Molecular, phylogenetic and predictive functional characterization of the isolated bacterial population was done using 16S rRNA sequencing coupled with Tax4Fun tools. Furthermore, representative isolates were screened for important enzymes (cellulase, xylanase, amylase, and protease) and heavy metal tolerance (chromium, arsenic) properties. A total of 454 bacterial isolates obtained were mapped into 57 unique bacterial genera and 4 different bacterial phyla. Interestingly, 37 genera not previously isolated from Indian hot springs, were isolated for the first time in the present study. However, most of these genera (23 out of 37) were reported only in metagenomics studies from Indian and global hot springs. Furthermore, around 14 genera not previously cultivated and not detected in metagenomics studies of hot springs are documented here. The metabolic potential was ascertained by determining the abundance of specific genes using in silico based Tax4Fun tool, which identified around 315 metabolic pathways for metabolism of carbohydrates, synthesis of secondary metabolites and degradation of xenobiotic compounds. Bioprospection study revealed that 33 and 25 bacterial genera were positive for enzyme production and resistance to the heavy metals, respectively. The present study revealed the advantages of cultivation methods using a comprehensive multiple isolation approach for exploring untapped and unique bacterial diversity, and also utilities for various biotechnological and environmental applications.