NITROGEN AND SMECTITES FROM TERRESTRIAL HOT SPRINGS IN THE UZON CALDERA, KAMCHATKA, FAR-EASTERN RUSSIA

摘要

The Uzon Caldera constitutes a large geothermal region that includes varied high-temperature, acidic, and strong redox environments hosting novel life forms. Springs and associated microbial mats and sediments were sampled within this context, to characterize the thermophilic and hyperthermophilic microbial populations. Carboxydotrophs, ferric iron reducers, sulfate reducers, and arsenate reducers among others were targeted through isolation of novel species, MPN field incubations, 16S rDNA clone libraries, metagenomic libraries, enrichment culturing, and radiotracer experiments. We have isolated new species/genera related to Carboxydocella, Dictyoglomus, Thermoanaerobacter, Thermobaculum, Geobacillus, Bacillus, and Anoxybacillus. PLFA profiles and lipid stable isotope measurements have provided an independent survey of the major clades present and dominant carbon fixation pathways. Archaeal lipid biomarkers (GDGTs) in Uzon are different from those in other hot springs such as those found in Nevada and California.