HR: 1340h
AN: OS33B-1270    [Abstracts]
TI: Stable isotope probing of chemoautotrophic biomarkers in the Cariaco Basin
AU: * Turich, C
EM: courtney.turich@skio.usg.edu
AF: Skidaway Institute of Oceanography, 10 Ocean Science Circle, Savannah, GA 31411, United States
AU: Taylor, G
EM: gtaylor@notes.cc.sunysb.edu
AF: Marine Sciences Research Center, State University of New York at Stony Brook, Stony Brook, NY 11794-5000, United States
AU: Podlaska, A
EM: apodlaska@notes.cc.sunysb.edu
AF: Marine Sciences Research Center, State University of New York at Stony Brook, Stony Brook, NY 11794-5000, United States
AU: Wakeham, S G
EM: stuart.wakeham@skio.usg.edu
AF: Skidaway Institute of Oceanography, 10 Ocean Science Circle, Savannah, GA 31411, United States
AB: In the redoxcline (250-450 m) of the Cariaco Basin, particulate carbon, nitrogen, and biomass (prokaryote, flagellate, viral) concentrations can be > 2-fold the concentrations found in the upper water column. Chemoautotrophic production is sufficient to meet the carbon demands in the redoxcline, yet local electron donor and acceptor sources are insufficient to account for the energy demands of this chemoautotrophy. Parallel experiments using thiosulfate amendments produced a depth-dependent 4 to 33-fold increase in the 14C fixation rate. We are using stable isotope probing on redoxcline waters incubated with 13C labeled bicarbonate and 15N-ammonium with and without thiosulfate amendments to establish the phylogeny and identify the lipid biomarkers associated with the active chemoautotrophic microbes. In incubations with only H13CO3- (and 15N- ammonium) addition (nr5), fatty acid 16:2 had the highest percent of label uptake (~25%). 16:1, 18:u and 14:1 all had >20% 13C incorporation. Other fatty acids with moderate (5-15%) 13C uptake include 12:0, 14:0 16:0, 18:1w7. Very low uptake was observed in i-15:0, a15:0; 15:0, 18:1w9, and 18:0 were all present but did not incorporate detectable 13C. In incubations with thiosulfate added with the H13CO3- (and 15N- ammonium; nr7), the total amount of fatty acids was at least 4x greater. There was also both a shift in the distribution of fatty acids incorporating the label and an increase in the total amount of label incorporation. Fatty acids with >30% 13C include 12:0, 14:1, 14:0, 2 isomers of 16:1, 18:u, and 18:w7. 16:0 also incorporated 13C (~28%). As in nr5, 15:0, a15:0; 15:0, 18:1w9 and 18:0 were all present but showed no 13C enrichment. The labeled fatty acids are consistent with production by sulfur oxidizers. 13C labeled carbon was incorporated into a suite of fatty acids known to be produced by sulfur oxidizers (e.g. Thioploca); production of these lipids also appears to be stimulated with the addition of thiosulfate. On-going work will analyze the phylogenetic affiliations of 13C and 15N labeled DNA, and future experiments will include other potential electron donors and acceptors.
DE: 4802 Anoxic environments (0404, 1803, 4834, 4902)
DE: 4825 Geochemistry
DE: 4840 Microbiology and microbial ecology (0465)
SC: Ocean Sciences [OS]
MN: 2007 Fall Meeting