HR: 11:35h
AN: B12B-06    [Abstracts]
TI: Lipid Biomarkers and Stable Isotope Signatures of Microbial Mats in Hot Springs of Kamchatka, Russia
AU: * Romanek, C S
EM: romanek@srel.edu
AF: Department of Geology, University of Georgia, Athens, GA 39602 United States
AU: * Romanek, C S
EM: romanek@srel.edu
AF: Savannah River Ecology Laboratory, Drawer E, Aiken, SC 29802 United States
AU: Mills, G L
AF: Savannah River Ecology Laboratory, Drawer E, Aiken, SC 29802 United States
AU: Jones, M E
AF: Savannah River Ecology Laboratory, Drawer E, Aiken, SC 29802 United States
AU: Paddock, L
AF: Savannah River Ecology Laboratory, Drawer E, Aiken, SC 29802 United States
AU: Li, Y
AF: Savannah River Ecology Laboratory, Drawer E, Aiken, SC 29802 United States
AU: Zhang, C L
AF: Savannah River Ecology Laboratory, Drawer E, Aiken, SC 29802 United States
AU: Zhang, C L
AF: Department of Marine Sciences, University of Georgia, Athens, GA 30602 United States
AU: Wiegel, J
AF: Department of Microbiology, University of Georgia, Athens, GA 30602 United States
AB: Various hot springs of the Uzon Caldera, Kamchatka, were analyzed for their chemical and stable isotope composition to better understand the relationship(s) between thermophilic microorganisms and the environments in which they live. The springs had water temperatures ranging from 40-90\deg C and pH ranging from 5.6-5.9. Gases that emanated from the springs were composed predominantly of CO$_{2}$ (20 to 90%), with lesser amounts of CH$_{4}$, ($<$ 20%), H$_{2}$, NH$_{3}$ and SO$_{2}$. Because the springs were acidic, they contained little dissolved inorganic carbon (DIC: millimol L$^{-1}$) and sulfide ($<$ 200 ppb), yet in some cases where microbial activity was relatively high, these constituents reached the millimol L$^{-1}$ and ppm range, respectively. Total biomass displayed a relatively large range of carbon isotope compositions that ranged from -5.7 to -22.4 per mil, which may reflect the large range of carbon sources, varied CO$_{2}$ fixation pathways, or other unknown mechanisms. Microbial mats were freeze-dried and extracted for lipid biomarker analysis. The lipids were separated into hydrocarbon, sterol, ether lipid, free fatty acid, and phospholipid fatty acid (PLFA) fractions. Among these fractions, PLFA indicated the community structure and abundance for Bacteria while the ether lipid fraction provided analogous information for Archaea. Results of PLFA showed 16:0 as the most abundant fatty acid (33-44%), which is universal in all living organisms. Other significant biomarkers included 18:1$\omega$ (19 to 24%), 18:2$\omega$ (5 to 13%), 16:1$\omega$ (3 to 12%), and 18:0 (2 to 7%). These biomarkers are characteristic of cyanobacteria, green-sulfur bacteria, and green non-sulfur bacteria, respectively, which are common autotrophic organisms in terrestrial hot springs. On the other hand, biomarkers of heterotrophic bacteria, such as iso- and anteiso-15:0 were low (2-8%), indicating that the bacterial carbon cycle was dominated by autotrophic organisms. Analogous archaeal constituents were present in significant abundance in the ether lipids fraction.
DE: 8424 Hydrothermal systems (8135)
DE: 4870 Stable isotopes
DE: 1055 Organic geochemistry
DE: 0400 Biogeosciences
SC: Biogeosciences [B]
MN: 2004 AGU Fall Meeting