Observations on Microbial CO-Oxidation in Marine Systems: Dynamics of CO and Enrichment of CO Oxidizers

April 17th, 2004

Oceans emit small amounts of carbon monoxide (CO) adding to the total CO load in the atmosphere. The hydroxyl radical is the primary sink for CO and other greenhouse gases. Therefore, the amount of CO in the atmosphere indirectly controls the residence time of greenhouse gases. Most CO in marine waters is derived from the photodegredation of dissolved organic matter. However, marine bacteria can utilize CO for energy and the synthesis of cellular components, thereby reducing the CO load to the atmosphere.

The ability to oxidize CO appears to be widespread among aerobic bacteria allowing them to utilize CO as a carbon source when organic sources of carbon are scarce (King, 2003). In fact, many CO-oxidizing bacteria may function preferentially as heterotrophs, metabolizing organic carbon.

We undertook this study to determine the impacts of heterotrophic substrates on CO-oxidation and to characterize members of the marine CO-oxidizing community in the Damariscotta River ( Walpole , ME. ). We examined CO production and consumption in surface water samples amended with organic substrates. We also isolated two novel strains of marine microbes (G15 and P10) from marine macroalgae. Both strains have been identified to genus level via DNA sequencing of 16S rDNA. Additional molecular, biochemical and physiological studies were carried out to learn more about the metabolism and ecological function of these newly isolated strains. Our data expands the diversity of known CO-oxidizers and our knowledge of specific strains which contributes to CO consumption in marine systems.

Carolyn Weber, ’04 Crystal Lake , IL
Majors: Biochemistry & Molecular Biology and Chemistry
Gary M. King
Professor of Oceanography and Microbiology, Darling Marine Center
Sponsor: Craig Tepper

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