ROY C, MONDAL N, PEKETI A, FERNANDES S, MAPDER T, VOLVOIKAR S P, HALDAR P K, NANDI N, BHATTACHARYA T, MAZUMDAR A
045213 ROY C, MONDAL N, PEKETI A, FERNANDES S, MAPDER T, VOLVOIKAR S P, HALDAR P K, NANDI N, BHATTACHARYA T, MAZUMDAR A (Microbiology Dep, Bose Institute, Kolkata- 700 054) : Geomicrobial dynamics of Trans-Himalayan sulfur–borax spring system reveals mesophilic bacteria’s resilience to high heat. J Earth Syst Sci 2020, 129(1), 10.1007/s12040-020-01423-y.
Geomicrobiology of sulfur–boron-dominated, neutral-pH hydrothermal systems was revealed in a Trans-Himalayan spring named Lotus Pond, located at 4436 m, in Puga Valley, Ladakh (India), where water boils at 85 °C. Water sampled along Lotus Pond’s outflow (vent to an adjacent river called Rulang), representing an 85–14 °C gradient, had high microbial diversity and boron/chloride/sodium/sulfate/thiosulfate concentration; potassium/silicon/sulfide/sulfite was moderately abundant, whereas cesium/lithium small but definite. Majority of the bacterial genera identified in the 85–72 °C samples have no laboratory-growth reported at >45 °C, and some of those mesophiles were culturable. Sulfur-species concentration and isotope-ratio along the hydrothermal gradient, together with the distribution of genera having sulfur-oxidizing members, indicated chemolithotrophic activities in the 85–72 °C sites. While biodiversity increased in the vent-to-river trajectory all-day, maximum rise was invariably between the vent (85–81 °C) and the 78–72 °C site; below 72 °C, diversity increased gradually. Biodiversity of the vent-water exhibited diurnal fluxes relatable to the sub-surface-processes-driven temporal fluxes in physicochemical properties of the discharge. Snow-melts infiltrating (via tectonic faults) the ~160 °C geothermal reservoir located within the breccia, at ~450 m depth, apparently transport mesophilic microbes into the thermal waters. As these micro-organisms emanate with the vent-water, some remain alive, illustrating that natural bacterial populations are more heat-resilient than their laboratory counterparts.