The valley of Geysers, is a multi-habitat environment for microorganisms, ranging from moderate to extreme environmental conditions within short distances. The aim of the present study is to characterize and compare the microbial communities in variable habitats: thermal water pools, outflow transect from a geyser to the Geysernaya river, river bed samples and a recently reactivated geyser in the river buried in landslides in 2007 and 2014. The study combines organic geochemical and geomicrobiological approaches with hydrochemical background data.
The different microbial habitats exhibit a wide range of different cell membrane biomarkers. Hot habitats are dominated by markers for archaea with lower abundances of bacterial biomass, indicating the presence of extremophiles in these habitats. Along the transect from a geyser to the river, the microbial community is dominated by bacteria with specific markers pointing to photosynthetic microbs. The river bed samples show only small amounts of bacterial biomass. A closer look at the taxonomy of the microbial communities of the different locations supports the clear difference between the communities influenced by hot and temperate water. Along the transect, the two sample at the upper end of the outflow (closer to the geyser, 66-84°C water temperature) show many extremophilic archaeal and also bacterial taxa, while the lower samples (around 32-39°C temperature) are characterized by mesophilic bacterial taxa with even some cyanobacteria. Initial result indicates the existence of unknown species within the communities. Overall, the microbial communities show a high spatial variability determined by the thermal conditions of the different life habitats.