Physicochemical and Microbial Diversity Analyses of Indian Hot Springs

Abstract

In the present study, physicochemical and microbial diversity analyses of seven Indian hot springs were performed. The temperature at the sample sites ranged from 32 to 67°C, and pH remained neutral to slightly alkaline. pH and temperature influenced microbial diversity. Culture-independent microbial diversity analysis suggested bacteria as the dominant group (99.3%) when compared with the archaeal group (0.7%). Alpha diversity analysis showed that microbial richness decreased with the increase of temperature, and beta diversity analysis showed clustering based on location. A total of 131 strains (divided into 12 genera and four phyla) were isolated from the hot spring samples. Incubation temperatures of 37 and 45°C and T5 medium were more suitable for bacterial isolation. Some of the isolated strains shared low 16S rRNA gene sequence similarity, suggesting that they may be novel bacterial candidates. Some strains produced thermostable enzymes. Dominant microbial communities were found to be different depending on the culture-dependent and culture-independent methods. Such differences could be attributed to the fact that most microbes in the studied samples were not cultivable under laboratory conditions. Culture-dependent and culture-independent microbial diversities suggest that these springs not only harbor novel microbial candidates but also produce thermostable enzymes, and hence, appropriate methods should be developed to isolate the uncultivated microbial taxa.

Diversity and Co-Occurrence Patterns of Fungal and Bacterial Communities from Alkaline Sediments and Water of Julong High-Altitude Hot Springs at Tianchi Volcano, Northeast China

“…The contribution of autotrophic taxa and the flexibility of bacteria to explore different nutrient sources may explain the complicated mutualistic bacterial network described in this study. The phylum Chloroflexi had the highest correlation with other members in the whole bacterial network, which is consistent with the result reported by Narsing Rao et al [18] in a study on physicochemical and microbial diversity in hot springs from three Indian provinces. Although Proteobacteria had a higher relative abundance, this phylum showed a lower level of network correlations compared to less abundant phyla, both in our study and in the previous work performed in India [18], thus suggesting a certain degree of specificity in the interactions between microbes, irrespective of their abundance.…”

“…In addition to the unusual high temperature, various dissolved minerals, such as magnesium, calcium, sodium, chlorides, sulfates, or silica, generally distinguish geothermal water from nongeothermal groundwater [10], thus supporting the presence of distinct microbial communities. For decades, researchers have been exploring the microbial diversity of thermal ecosystems in different continents worldwide, including the near-boiling silica-depositing thermal springs at Yellowstone National Park in the USA [11], hot springs with a wide range temperature (22-75 • C) across the Tibetan Plateau of China [12], intertidal hot springs of Iceland [13], acidic thermal pools of Russia [14], and alkaline hot springs of Kenya [15], using traditional culture-dependent methods [16][17][18], as well as recently developed high-throughput sequencing [15,18]. Novel thermophilic, alkaliphilic, and metal-tolerant species able to produce valuable biotechnological products, such as antibiotics [8], bioethanol [19], and thermostable enzymes [20], have been frequently discovered from hot springs [5,19,21].…”

“…Huo and coauthors [27] showed that pH was a crucial parameter driving the differences in bacterial and archaeal communities between two analyzed hydrothermal areas of the Tengchong hot spring system in Yunnan Province, China. However, the majority of recent studies investigating geothermal environments mainly focused on the diversity of bacterial and archaeal communities [12][13][14][16][17][18], while the diversity and function of fungal communities received much more limited attention [15,25,28].…”

Developing Bioprospecting Strategies for Bioplastics Through the Large-Scale Mining of Microbial Genomes

“…The areas, around which hydrothermal fluid circulate, are rich in carbon and are dominated by microbial thermophilic methanogens ( Minic and Thongbam, 2011 ; Ver Eecke et al, 2012 ). Hot springs are similar in setting, except the water source comes from groundwater and is also rich in microbial life ( Urschel et al, 2015 ; Narsing Rao et al, 2021 ). From observation of environmental PhaC genotypes from niche environments, it seems that PHA producers can be readily found in extremophiles containing extreme physicochemical conditions, so long as there is an abundant carbon source.…”

Analysis of Soil Fungal and Bacterial Communities in Tianchi Volcano Crater, Northeast China

“…To overcome this limitation, diverse methods have been developed to obtain genetic information on the presence of microorganisms living in natural environments. These methods allow the culture-independent analysis of the total microbial genomes called Life 2021, 11, 280 2 of 18 "metagenome" in a particular environment [2,[11][12][13]. The development of molecular biological techniques (particularly high-throughput sequencing) represents a powerful tool to access a much larger proportion of microbial communities, compare to traditional culture-based methods, by means of environmental sample total DNA extraction [14].…”