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

Geomicrobiologies of the hot springs of Chumathang and Panamik (located in the Indus and Nubra valleys of eastern and northern Ladakh, respectively) were revealed and compared with the Lotus Pond spring of Puga Valley (eastern Ladakh), which is known for its mineralogical and ecological peculiarities. Physicochemically, the vent-waters of the explored springs, Chumathang_01, Panamik_01 and Panamik_02, were distinct from Lotus Pond, with wide variations in boron, chloride, lithium, magnesium and potassium concentrations. Their microbiomes encompassed several unique constituents, but resembled Lotus Pond in being highly diversified and bacterial-mesophiles-dominated. Higher diversities of thermophilic archaea were detected in Chumathang_01 compared to Panamik_01 or Panamik_02. Statistical analysis of the geochemical and microbiological data highlighted the overall uniqueness of Lotus Pond, the constraint imposed by high temperature on the diversity of most bacterial groups, and the potential role of in-situ geochemicals in helping mesophilic bacteria inhabit the high-temperature environments. While the microbiome architecture of the 86°C Chumathang_01 (having the highest bacterial species count) closely resembled that of the geochemically similar 78°C Panamik_01, both the biomes were apparently shaped by temperature and pH. In contrast, the distinctive geochemistry of the 81°C Lotus Pond was apparently instrumental in sustaining a microbiome similar to that of the cooler (70°C) Panamik_02.