Abstract
Hot springs are considered to be a unique environment with extremophiles, that are sources of industrially important enzymes, and other biotechnological products. The objective of this study was to undertake, analyze, and characterize the microbiome of two major hot springs located in the state of Madhya Pradesh explicitly, Chhoti Anhoni (Hotspring 1), and Badi Anhoni (Hotspring 2) to find out the inhabitant microbial population, and their functional characteristics. The taxonomic analysis of the microbiome of the hot springs revealed the phylum Proteobacteria was the most abundant taxa in both the hot-springs, however, its abundance in hot-spring 1 (~88%) was more than the hot-spring 2 (~52%). The phylum Bacteroides (~10–22%) was found to be the second most abundant group in the hot-springs followed by Spirocheates (~2–11%), Firmicutes (~6–8%), Chloroflexi (1–5%), etc. The functional analysis of the microbiome revealed different features related to several functions including metabolism of organics and degradation of xenobiotic compounds. The functional analysis showed that most of the attributes of the microbiome was related to metabolism, followed by cellular processes and environmental information processing functions. The functional annotation of the microbiomes at KEGG level 3 annotated the sequences into 279 active features that showed variation in abundance between the hot spring samples, where hot-spring 1 was functionally more diverse. Interestingly, the abundance of functional genes from methanogenic bacteria, was higher in the hot-spring 2, which may be related to the relatively higher pH and temperature than Hotspring 1. The study showed the presence of different unassigned bacterial taxa with high abundance which indicates the potential of novel genera or phylotypes. Culturable isolates (28) were bio-prospected for industrially important enzymes including amylase, protease, lipase, gelatinase, pectinase, cellulase, lecithinase, and xylanase. Seven isolates (25%) had shown positive results for all the enzyme activities whereas 23 isolates (82%) produced Protease, 27 isolates (96%) produced lipase, 27 isolates produced amylase, 26 isolates (92%) produced cellulase, 19 isolates (67%) produced pectinase, 19 isolates (67%) could produce lecithinase, and 13 isolates (46%) produced gelatinase. The seven isolates, positive for all the enzymes were analyzed further for quantitative analysis and identified through molecular characterization.
Highlights
Extremophilic microorganisms thrive in diverse and extreme conditions and constitute a major part of the biosphere (Mirete et al, 2016)
Dissolved oxygen (DO), Biological oxygen demand (BOD), and chemical oxygen demand (COD) were measured to understand the level of oxygen concentration. Both samples Hot-spring1 and Hot-spring2 had shown BOD in the normal range but the COD of sample Hot-spring2 was found to be much higher than Hot-spring1 demonstrating the presence of more organics in the water
Different other factors like available organic carbon, total dissolved solids, salt concentration play a crucial role in shaping the microbial community structure as the microbial diversity do not have a monotonic relationship with temperature, where different other environmental or spatial factors may be responsible for determining the microbial community (Purcell et al, 2007)
Summary
Extremophilic microorganisms thrive in diverse and extreme conditions and constitute a major part of the biosphere (Mirete et al, 2016). The accessibility of thermophiles to survive at high temperatures is related to their incredibly thermostable macromolecules present in them (Brock, 2001) These thermophilic microorganisms have been studied extensively for thermostable enzymes such as amylases, cellulases, chitinases, pectinases, xylanases, proteases, lipase, and DNA polymerases, etc. Industrially important enzymes from thermophiles such as amylase (extracellular), protease (extracellular), lipase (extra/intracellular), gelatinase (extracellular), pectinase (extra/intracellular), cellulase (extra/intracellular), lecithinase (extracellular), and xylanase (extracellular) has been used extensively. Most of these enzymes are found to be optimally active at temperatures close to the host organism’s optimal growth temperature. Some of the extracellular and cell-bound hyperthermophilic enzymes were optimally active at temperatures above, sometimes far above than the host organism’s optimum growth temperature (Vieille and Zeikus, 2001)
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