Microbial diversity in acidic thermal pools in the Uzon Caldera, Kamchatka

Abstract

Microbial communities of four acidicthermal pools in the Uzon Caldera, Kamchatka,Russia, were studied using amplification and pyrosequencingof 16S rRNA gene fragments. The sitesdiffered in temperature and pH: 1805 (60 C, pH 3.7),1810 (90 C, pH 4.1), 1818 (80 C, pH 3.5), and 1807(86 C, pH 5.6). Archaea of the order Sulfolobaleswere present among the dominant groups in all fourpools. Acidilobales dominated in pool 1818 but were aminor fraction at the higher temperature in pool 1810.Uncultivated Archaea of the Hot Thaumarchaeotarelatedclade were present in significant quantities inpools 1805 and 1807, but they were not abundant inpools 1810 and 1818, where high temperatures werecombined with low pH. Nanoarchaeota were presentin all pools, but were more abundant in pools 1810 and1818. A similar abundance pattern was observed forHalobacteriales. Thermophilic Bacteria were lessdiverse and were mostly represented by aerobichydrogen- and sulfur-oxidizers of the phylum Aquificaeand sulfur-oxidising Proteobacteria of the genusAcidithiobacillus. Thus we showed that extremelyacidic hot pools contain diverse microbial communitiescomprising different metabolic groups of prokaryotes,including putative lithoautotrophs using energysources of volcanic origin, and various facultative andobligate heterotrophs