HR: 0800h
AN: B41C-0211    [Abstracts]
TI: Change in Microbial Community with Salinity in the Sediment of Lake Chaka, a hypersaline lake in Northwestern China
AU: * Jiang, H
EM: jiangh@muohio.edu
AF: Miami University, 114 Shideler Hall, Department of Geology, Miami University, Oxford, OH 45056 United States
AU: Yu, B
EM: yubs@cugb.edu.cn
AF: China University of Geosciences, Beijing, School of Earth Sciences, XueYuan Road 29, Haidian District, China University of Geosciences, Beijing, 100083 China
AU: Dong, H
EM: dongh@muohio.edu
AF: Miami University, 114 Shideler Hall, Department of Geology, Miami University, Oxford, OH 45056 United States
AU: Li, Y
EM: Li@srel.edu
AF: University of Georgia, Savannah river Ecology Laboratory and Marine Sciences Department, University of Georgia, P.O. Box Drawer E, Aiken, SC 29802 United States
AU: Zhang, C
EM: zhang@srel.edu
AF: University of Georgia, Savannah river Ecology Laboratory and Marine Sciences Department, University of Georgia, P.O. Box Drawer E, Aiken, SC 29802 United States
AB: Lake Chaka (36°18'-36°45'N,99°02'-99°12'E), 3800 m above sea level, is located on the Qinghai-Tibetan Plateau, northwestern China, where semi-arid continental climate dominates. The basin of Lake Chaka is about 80 km long and 30 km wide. Strong evaporation and little precipitation (2264 mm evaporation versus 224 mm rainfall/year) in this area have resulted in a nearly dry lake and high salinity (21%). The pH of lake water is 7.4. In November 2004, a sediment core of 10 m in length was collected in Lake Chaka. This sediment core covered a salinity gradient from fresh water at the bottom of the core (10-m depth) to near salt saturation at the surface. Mineralogy also changed with depth, ranging from mud-fine sands at the bottom to mirabilite (Na2SO4) and gypsum in the middle to halite near the top. The biomass determined by acridine orange direct count (AODC) in the sediment core was about 108 cells per gram of wet sample from the bottom to the top. Microbial diversity and community structure as determined by phospholipid fatty acid analysis (PFLA) and 16S rRNA gene analyses in the sediment systematically changed with increasing salinity. Overall, microbial diversity decreased with increasing salinity. At the bottom, freshwater microorganisms are dominant. Near the top of the core, halophilic bacteria and archaea are predominant microorganisms. This systematic change in microbial diversity and community structure is a result of microbial response to progressive increase in salinity in the last 50,000 years.
DE: 0456 Life in extreme environments
SC: Biogeosciences [B]
MN: Fall Meeting 2005