Indus and Nubra Valley hot springs affirm the geomicrobiological specialties of Trans-Himalayan hydrothermal systems

Aquificae overcomes competition by archaeal thermophiles, and crowding by bacterial mesophiles, to dominate the boiling vent-water of a Trans-Himalayan sulfur-borax spring

“…On the other flank of the hot water pool, a wall of travertine, sulfur, and boron mineral deposits [10,16] guard the crater and debars the spring-water from escaping the pool (Fig 1C). Water (having temperature 85°C and pH 7.5) was collected as described at length previously [5,10,17,18] from Lotus Pond's vent at 13:00 h of 29 October 2021, when ebullition was strong and fumarolic activity copious. For microscopic studies, 500 mL vent-water was passed through a sterile 0.22 μm mixed cellulose ester membrane filter (Merck Life Science Private Limited, India) having a diameter of 47 mm, and inserted into a sterilized cryovial containing 5 mL of autoclaved 0.9% (w/v) NaCl solution supplemented with 15% (v/v) glycerol.…”

“…Conversely, as the bioenergetic cost of cell system maintenance get relaxed down the temperature gradient, habitability, and therefore in situ diversity, increases for most microbial taxa except for the true thermophiles [11,12]. Idiosyncratic to the low-biodiversity community structure axiomatic for hydrothermal vent ecosystems, a geochemically unusual category of Trans-Himalayan hot springs, located on the either side of the tectonically active Indus Tsangpo Suture Zone (ITSZ, the collision intersection between the Asian and Indian continental crusts engaged in Himalayan orogeny) in eastern Ladakh, India [13][14][15][16], has recently been reported for their extra-ordinarily diversified vent-water microflora [5,10,17,18]. Compared with other well studied hydrothermal systems, the geochemical specialty of these Trans-Himalayan hot springs lies in their paucity of dissolved solids in general and calcium and silicon in particular, which again is accompanied by the exceptional abundance of boron, chlorine, sodium, and various sulfur species including both sulfide and sulfate.…”

Fluctuation of gut microbiome in Cirrhinus mrigala is associated with changes in dissolved oxygen of water

“…To improve accuracy and diversity estimates, the resulting sequence was ltered for quality value 20 once more and reads shorter than 100 bp were trimmed using FASTX-Toolkit predictions (v0.0.13.2). USEARCH was used for clustering, and operational taxonomic units (OTUs) were created with a cut-off of 97% 16S rRNA gene sequence identity (Edgar 2013;Mondal et al 2022). Singletons were removed before clustering into OTUs.…”

Thermal Endurance by a Hot-Spring-Dwelling Phylogenetic Relative of the Mesophilic Paracoccus

“…Accordingly, our knowledge on microbial adaptation to high temperature is based largely on hot spring isolates that grow in vitro either obligately at ≥80°C ( 1 , 2 ) or facultatively between 30°C and 80°C ( 3 , 4 ). Members of mesophilic microbial groups (taxa having no member reported for laboratory growth at >45°C), on the other hand, though unexpected in high-temperature environments, often get stochastically introduced by local geodynamic forces to the hot spring systems ( 5 – 7 ), where they are detected mostly via sequencing and analysis of metagenomes ( 6 – 15 ), and sometimes as pure culture isolates ( 12 , 16 , 17 ). In such a scenario, for a holistic understanding of microbial life’s high-temperature adaptation, it becomes imperative to explore the biology of the phylogenetic relatives of mesophilic bacteria which happen to be there in geographically and geologically distinct hot spring habitats.…”