Investigating carbon monoxide (CO) consumption in the marine bacterium Silicibacter pomeroyi (DSS3) with coxL gene expression

The main sink for photochemically produced carbon monoxide is bacterial consumption. Understanding bacterial CO consumption is critical for evaluation of the oceanic CO cycle. Silicibacter pomeroyi (DSS3) is a marine bacterium that consumes CO as an energy source. Genomic analysis of S. pomeroyi reveals the presence of two operons encoding aerobic carbon monoxide dehydrogenase, the enzyme mediating oxidation of CO to CO. Here we describe gene expression of the large subunit (coxL) in response to varying CO concentration, the CO oxidation rate of S. pomeroyi, and the oceanic significance of CO consumption. Gene expression was examined in S. pomeroyi inoculated into seawater media with and without CO. Various primer sets were designed and screened through reverse transcription polymerase chain reaction and gel electrophoresis. An oxidation rate was calculated based on cell numbers and the consumption of CO over time. Bacterial impact on oceanic [CO] was modeled based on this CO oxidation rate constant. Initial results suggest that expression of coxL by S. pomeroyi may be constitutive.