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General Session 3: Biological oceanography & global change |
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Distribution and phylogenetic diversity of cbbM genes encoding rubisco form ii in surface sediments of the western pacific ocean
GS3-09-S
Kanagarajan Umapathi* , Institute of Marine Microbes and Ecospheres and State Key Laboratory of Marine Environmental Science, Xiamen University, Xiamen, China
Dang Hongyue, Institute of Marine Microbes and Ecospheres and State Key Laboratory of Marine Environmental Science, Xiamen University, Xiamen, China
Selvaraj Kandasamy, State Key Laboratory of Marine Environmental Science and Department of Geological Oceanography, Xiamen University, Xiamen, China
Presenter Email: marinekanagarajan@gmail.com
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| Chemolithoautotrophy is an important component of carbon recycling in shallow marine sediments, leading to accumulation of high amounts of reduced elements such as sulfide, iron, nitrogen and ammonium due to intense aerobic and anaerobic mineralization. Chemolithoautotrophic bacteria play a major role in this process and responsible for chemoautotrophic biomass production in marine sediments. Here, we quantify and sequence form II cbbM (RuBisCO) genes in surface sediment samples collected at different water depths (10-1500 m) from the marginal seas of the western Pacific Ocean (WPO) to determine the distribution of chemolithoautotrophic bacteria. A total of 1099 WPO clones were randomly picked out from the cbbM clone library and identified as positive transformant by PCR. Some clones from the South China Sea and Sea of Okhotsk show 90% similarity to SUP05 and γ-Proteobacteria group available in this area. The identification of cbbM transcripts affiliated with SUP05 is consistent with the idea that these organisms are active members of the chemolithoautotrophic community of pelagic environment. Although the contribution of SUP05 to marginal sea chemolithoautotrophic production is currently unknown, our detection of cbbM gene conveyable to SUP05 supports the chemolithoautotrophic activity. The cbbM gene probably rise from SUP05 cells support for the chemolithoautotrophic activity express of this phylogenetic group. Our findings also show high abundance of SUP05 group plays a substantial role in carbon fixation. Quantitative PCR (qPCR) analyses of cbbM genes reveal moderate abundances in deeper than shallower sediments, indicating that carbon fixation by chemolithoautotrophic bacteria is likely a major pathway in marine sediments. This study is the first functional gene approach performed by targeted key enzyme of RuBisCO (cbbM) biogeochemical pathways involved in carbon fixation autotrophy in coastal and deep marine environmental samples. This current study offers a fundamental knowledge about the autotrophic potential of bacteria for CO2-fixation and occurrence of a specific functional bacterial diversity as well as via the RuBisCO pathway in marginal sea sediments. Key words: RuBisCO form II, cbbM gene, Carbon fixation, Chemolithoautotroph, Marine sediment, Bacterial diversity. |
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