HR: 0800h
AN: B21A-1014 [Abstracts]
TI: Fatty Acid and Carbon Isotopic Evidence for type I Methanotrophs in Microbial Mats from a Shallow
Marine Gas Seep, Coal Oil Point, CA.
AU: * Ding, H
EM: dinghb701017@yahoo.com
AF: Department of Earth Science, University of California, Santa Barbara, Goleta, CA 93106
United States
AU: * Ding, H
EM: dinghb701017@yahoo.com
AF: Marine Science Insititute, University of California, Santa Barbara
Bldg. 520, Goleta, CA 93106-6150
United States
AU: Valentine, D
EM: valentine@geol.ucsb.edu
AF: Marine Science Insititute, University of California, Santa Barbara
Bldg. 520, Goleta, CA 93106-6150
United States
AB:
To study the microbial community in a Southern California seep field, sediment and bacterial mat samples were collected from
natural gas-bearing and gas-free surfaces at two distinct seeps in the Coal Oil Point seep field, offshore Santa Barbara.
Fatty acids in these samples were extracted, analyzed and identified. Using gas chromatography (GC), more than 30 different
fatty acids were separated. Generally, fatty acid concentrations in natural gas-bearing samples were about 5-fold higher
compared to gas-free samples. Using gas chromatography mass sepctrometry (GC-MS), all separated fatty acids were identified
in each sample. The major constituents included saturated 14:0, 16:0, 18:0, branched i-15, a-15 and unsaturated 16:1 and
18:1 series fatty acids. GC-IRMS (isotope ratio mass spectrometry) analysis provided the „13C of all major fatty acids and
some 16:1 series fatty acids were found to be more depleted than -40% in samples associated with gas seepage. After
treatment with dimethyl disufide (DMDS), the 16:1 series fatty acids were resolved into five distinct components, including
common composition 16:1(7), bacterial specific i-16:1(7) and typical biomarkers of type I methnotrophs 16:1(8), 16(6) and
16:1(5), suggesting an important role for methnotrophs in seep sediments and microbial mats. These results provide evidence
for the activity of type I methanotrophic bacteria in microbial mats and surficial sediments at the Coal Oil Point seep
field, and have implications for methane cycling in this and other seep
DE: 0330 Geochemical cycles (1030)
DE: 0428 Carbon cycling (4806)
DE: 0432 Contaminant and organic biogeochemistry (0792)
DE: 0448 Geomicrobiology
DE: 0460 Marine systems (4800)
SC: Biogeosciences [B]
MN: Fall Meeting 2005