INVESTIGATING MARINE MICROBIAL REACTIONS USING NOVEL APPROACHES: GENETICS AND BIOGEOCHEMISTRY

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2019-5-28

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Deliceırmak, Selin

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Despite the many important roles, they play, bacteria are one of the least known components of the marine biogeochemical cycles. In order to determine the temporal dynamics of the species composition, and active metabolisms playing significant roles in the nitrogen cycling we used the power of novel genetic analyses and integrate biochemical measurements. Community dynamics were studied using 16S rRNA amplicon sequencing approach. Samples were collected with monthly intervals for one year from different depths of monitoring station (bottom depth 200 m) in the NE Mediterranean. mRNA expressions of genes that are responsible for nitrogen cycling were investigated seasonally using metatranscriptomics. In total, 2213 sequence variants were observed among which Proteobacteria, Bacteroidetes and Cyanobacteria were the mostly observed phylum. In the higher taxonomic level, SAR 11 clade belonging to Pelagibacteriaceae was highly dominant in our samples and its ecotypes show variation with depth. While Clade Ia more dominant in the surface waters, Clade Ib was abundant in the deeper waters. Seasonality found to be the main driver for patterns in bacterial communities. Prochlorococcus MIT 9313 was more abundant than Synechococcus CC9902 in the surface during fall. Prochlorococcus MIT 9313 contributes more to the formation of DCM in our region. Additionally, metatranscriptomics results showed that the nitrogen fixation is not the dominant process in the study region. Genus Nitrospinae are responsible for the high concentrations of nitrate in the deeper waters. We showed the importance of bacteria in the carbon and nitrogen cycling in the NE Mediterranean.

Subject Keywords

16S rRNA amplicon sequencing, Metatranscriptomics, Eastern Mediterranean, Nitrogen Cycle, Phosphate Cycle

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https://hdl.handle.net/11511/95084

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Graduate School of Marine Sciences, Thesis

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Citation Formats

S. Deliceırmak, “INVESTIGATING MARINE MICROBIAL REACTIONS USING NOVEL APPROACHES: GENETICS AND BIOGEOCHEMISTRY,” M.S. - Master of Science, Middle East Technical University, 2019.