SREL Reprint #3210

Comparative Geochemical and Microbiological Characterization of Two Thermal Pools in the Uzon Caldera, Kamchatka, Russia

Elizabeth A. Burgess1, Jason M. Unrine2, Gary L. Mills1, Christopher S. Romanek3, and Juergen Wiegel4

1Savannah River Ecology Laboratory, University of Georgia, P.O. Drawer E, Aiken, SC 29802, USA
2Department of Plant & Soil Sciences, University of Kentucky, Lexington, KY, USA
3Department of Earth & Environmental Sciences, University of Kentucky, Lexington, KY, USA
4Department of Microbiology, University of Georgia, Athens, GA, USA

Abstract: Arkashin Schurf (Arkashin) and Zavarzin Spring (Zavarzin), two active thermal pools in the Uzon Caldera, Kamchatka, Russia, were studied for geochemical and microbiological characterization. Arkashin, the smaller of the two pools, had broader temperature and pH ranges, and the sediments had higher concentrations of total As (4,250 mg/kg) relative to Zavarzin (48.9 mg/kg). Glycerol dialkyl glycerol tetraether profiles represented distinct archaeal communities in each pool and agreed well with previous studies of these pools. Although no archaeal 16S rRNA sequences were recovered from Arkashin, sequences recovered from Zavarzin were mostly representatives of the Crenarchaeota and “Korarchaeota,” and 13% of the sequences were unclassifiable. The bacterial community in Arkashin was dominated by uncultured “Bacteroidetes,” Hydrogenobaculum of the Aquificales and Variovorax of the Betaproteobacteria, and 19% of the sequences remained unclassified. These results were consistent with other studies of As-rich features. The most abundant members of the Zavarzin bacterial community included the Chloroflexi, as well as members of the classes Deltaproteobacteria and Clostridia. In addition, 24% of the sequences were unclassified and at least 5% of those represent new groups among the established Bacterial phyla. Ecological structure in each pool was inferred from taxonomic classifications and bulk stable isotope δ values of C, N, and S. Hydrogenobaculum was responsible for primary production in Arkashin. However, in Zavarzin, the carbon source appeared to be allochthonous to the identified bacterial community members. Additionally, sequences related to organisms expected to participate in N and S cycles were identified from both pools.

SREL Reprint #3210

Burgess, E. A., J. M. Unrine, G. L. Mills, C. S. Romanek, and J. Wiegel. 2012. Comparative Geochemical and Microbiological Characterization of Two Thermal Pools in the Uzon Caldera, Kamchatka, Russia. Environmental Microbiology 2012(63): 471-489.

This information was provided by the University of Georgia's Savannah River Ecology Laboratory (srel.uga.edu).