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

Abstract

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.

Advances in Antarctic Research for Antimicrobial Discovery: A Comprehensive Narrative Review of Bacteria from Antarctic Environments as Potential Sources of Novel Antibiotic Compounds Against Human Pathogens and Microorganisms of Industrial Importance

“…The antagonistic properties of organisms inhabiting extreme environments have not been investigated as extensively as they have for mesophiles [17]; however, the traditional approach of isolating and cultivating new microorganisms from underexplored habitats is still productive [6]. In recent years, research has exploited untapped and extreme environments, including the polar regions, complex marine habitats, and hyperthermal environments, to discover novel bioactive compounds with antibacterial, antifungal, and antitumor properties, and apply them to current clinical challenges [15,18,19,20,21]. This review summarizes the findings from research on Antarctic bacteria producing antimicrobial compounds, in order to: (i) Highlight the importance of the Antarctic ecosystem as a promising source for discovering novel antibiotics, (ii) demonstrate the significance of a growing body of research focused on antimicrobial activity of Antarctic bacteria, and (iii) highlight the strains already isolated from different Antarctic regions and their potential application against human pathogens and phytopathogens and in other industrial and pharmaceutical applications.…”

Screening of Bacteria Producing Asparaginase Free of Glutaminase and Urease from Hot Springs in West Sulawesi

“…The isolation of oligotrophic bacteria which was conducted using dilute R2A medium reduced the blooming of fast-growing bacteria (Kumar, et al, 2014). Although, Firmicutes, including Bacilli were obtained in small number, this phylum are well known cosmopolitan and fast growing taxa since the medium used are not suitable for the bacteria (Mehetre, et al, 2018). The presence of genus Staphylococcus, Pseudomonas, and Rhodococcus as thermotolerant aquatic bacteria in this study was supported by the work of Kumar et al (2014).…”

Root-Zone Restriction Regulates Soil Factors and Bacterial Community Assembly of Grapevine

“…Magnesium was positively correlated with the Dienococus-Thermus phylum in control, while it was negative in treated plants. This may be because magnesium increases the production of the hydrolytic enzyme-producing bacteria, and this activity may be hindered by root-zone restriction [ 102 ]. A similar phylum remained possessed with a positive correlation with Fe in both the cultivation techniques because Fe-rich sources affect the diversity of Dienococus-Thermus, as reported by [ 103 ].…”