Marine microorganisms, either archaea or bacteria, are major players of the deep-sea carbon cycle, which applied highly diversified metabolic strategy to survive in the deep ocean. The marine ammonia-oxidizing archaea (AOA) can either fix inorganic carbon in autotrophic mode or absorb organic carbon in heterotrophic mode, of which Nitrosopumilus maritimus SCM1 is our research object. The Alteromonas machellii (AM) was known to be highly flexible in their carbon metabolism. This leaves the question how to trace the carbon metabolism of these microbes in the vast ocean. For this purpose, we cultured Alteromonas machellii using different carbon substrates, e.g. monosaccharides, amino acids, organic acids and so on. The addition of those substrate to the autotrophic SCM1 was also compared with the control. The amino acid and fatty acid carbon isotope values in the cellular content was analyzed in these cultures. The central metabolic behaviors were reconstructed using the isotopic fractionation among individual molecules in the cells. This information can be applied to trace the metabolic patterns of marine archaea and bacteria in the natural marine environments, as well as their contribution to the deep ocean carbon cycling.
 

ammonia-oxidizing archaea,Alteromonas Machellini,Compound-specific carbon isotope analysis,carbon metabolism