HR: 16:15h
AN: B24B-02    [Abstracts]
TI: Diversity of Arsenate Respiratory Reductase Genes Along Gradients of Arsenate and Arsenite Within Hypersaline, Alkaline Sediments
AU: * Saltikov, C W
EM: saltikov@etox.ucsc.edu
AF: University of California, Santa Cruz, Dept. of Environmental Toxicology, Santa Cruz, CA 95064 United States
AU: Nilsen, J
EM: jnilsen@ucsc.edu
AF: University of California, Santa Cruz, Dept. of Environmental Toxicology, Santa Cruz, CA 95064 United States
AU: Oremland, R S
EM: roremlan@usgs.gov
AF: United States Geological Survey, 345 Middlefield Road, Menlo Park, CA 94025 United States
AU: Kulp, T R
EM: trkulp@usgs.gov
AF: United States Geological Survey, 345 Middlefield Road, Menlo Park, CA 94025 United States
AU: Hoeft, S E
EM: sehoeft@usgs.gov
AF: United States Geological Survey, 345 Middlefield Road, Menlo Park, CA 94025 United States
AU: Miller, L G
EM: lgmiller@usgs.gov
AF: United States Geological Survey, 345 Middlefield Road, Menlo Park, CA 94025 United States
AU: Switzer Blum, J
EM: jsblum@usgs.gov
AF: United States Geological Survey, 345 Middlefield Road, Menlo Park, CA 94025 United States
AU: Baesman, S
EM: sbaseman@usgs.gov
AF: United States Geological Survey, 345 Middlefield Road, Menlo Park, CA 94025 United States
AU: Han, S
EM: hansk@ucr.edu
AF: University of California, Riverside, Dept. of Environmental Sciences, Riverside, CA 92521 United States
AU: Lanoil, B
EM: brian.lanoil@ucr.edu
AF: University of California, Riverside, Dept. of Environmental Sciences, Riverside, CA 92521 United States
AB: There are several soda lakes in western United States that contain high arsenic concentrations (up to 4 mM total As). Interestingly, these lakes have high rates of anaerobic arsenate reduction, which is catalyzed by arsenate respiring prokaryotes. Several cultured arsenate respiring prokaryotes have been shown to respire and reduce arsenate via a membrane-associated enzyme, ArrA. This enzyme is present in many diverse arsenate respiring prokaryotes. To investigate arsenate respiring microbial communities within these extreme environments, we used functional gene analysis to detect the presence, abundance, and diversity of the arrA gene in core samples collected from two arsenic enriched, hypersaline, alkaline lakes, Mono Lake and Searles Lake. Each sample exhibited concentration gradients for dissolved arsenic species and oxygen. Porewater arsenite concentration increased with depth and was correlated with oxygen depletion. To investigate the depth dependency of the arrA gene in these core samples we utilized the Malasarn et al. (2004) polymerase chain reaction (PCR) primers to detect a partial arrA gene fragment in nucleic acids extracted from sediment samples. The arrA gene fragment was detected only in the top 1-2 cm of the Mono Lake core and no detection was observed in the Searles Lake homogenized core. After the primers were redesigned to include the nucleotide codon bias for haloalkaliphilic archaea ( Halobacterium), the arrA gene fragments could be detected at each depth interval throughout the Mono Lake core and in the homogenized core of Searles Lake. Work is currently focused on characterizing the diversity and abundance of the arrA gene fragments obtained in each core sample and at different depths. Although no haloalkaliphilic arsenate respiring archaea have been isolated to date, these results suggest that the arrA gene fragments detected in these soda lakes may be of archaeal origins.
DE: 0448 Geomicrobiology
DE: 0456 Life in extreme environments
DE: 0465 Microbiology: ecology, physiology and genomics (4840)
SC: Biogeosciences [B]
MN: Fall Meeting 2005