H2-CO2-DEPENDENT ANAEROBIC O-DEMETHYLATION ACTIVITY IN SUBSURFACE SEDIMENTS AND BY AN ISOLATED BACTERIUM

The ability of microorganisms in sediments from the Atlantic Coastal Plain to biodegrade methoxylated aromatic compounds was examined. O-demethylation activity was detected in deep (121- and 406-m) sediments, as well as in the surface soil. A syringate-demethylating consortium, containing at least three types of bacteria, was enriched from a deep-sediment sample in a medium containing syringate as the sole organic carbon source and with a N2-CO2 atmosphere. An isolate which demethylated syringate was obtained from the enrichment on an agar medium incubated under a H2-CO2 but not a N2-CO2 or N, atmosphere. O demethylation of syringate of this isolate was dependent on the presence of both H2 and CO2 in the gas phase. The metabolism of syringate occurred in a sequential manner: methylgallate accumulated transiently before it was converted to gallate. Mass balance analysis suggests that the stoichiometry of the reaction in this isolate proceeds in accordance with the following generalized equation: C7H3O3(OCH3)n- + nHCO3- + nH2 C7H3O3(OH)n- + nCH3COO- + nH2O.