Towards a systematic understanding of aerobic methylated amine metabolism in the ocean

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Methylated amine compounds (MAs) are ubiquitous in the ocean and play significant roles in marine nutrient cycling and atmospheric chemistry. MAs are involved in the formation of aerosols and neutralization of atmospheric acidity resulting from the oxidation of nitrogen- and sulfur-containing compounds. MAs also contribute to the 'greenhouse effect' by the formation of nitrous oxide (N2O) and hydrogen cyanide (HCN) from their oxidation by hydroxyl radicals and ozone, and by being precursors for methane (CH4) produced by methanogens. Despite the global importance of marine MAs, modelling and quantifying their environmental impacts has been hindered by a paucity of data on the origins and sinks of these compounds. Microorganisms are known to use MAs as sources of energy and nutrients therefore affecting the concentrations of MAs in the ocean and hence fluxes across the air-sea interface; however, the identities of these key players and metabolic pathways remain largely unknown. The objective of this proposed research is to characterize the diversity and abundance of marine MA utilizers and to investigate the enzymology and regulation of MA-metabolizing pathways using model marine microorganisms. This research will test the hypothesis that MAs are used as a carbon (C) source by specialized methylotrophs (bacteria that use one-carbon (C1) compounds) in the ocean, and that diverse marine microorganisms can metabolize MAs as a source of nitrogen (N).