MICROBIAL POTENTIAL FOR THE ANAEROBIC DEGRADATION OF SIMPLE AROMATIC-COMPOUNDS IN SEDIMENTS OF THE MILWAUKEE HARBOR, GREEN BAY AND LAKE ERIE

The ability of microbial populations to mediate the anaerobic transfor mation of six aromatic compounds in sediments from the Milwaukee Harbo r, Green Bay, and Lake Erie was examined. Sediment slurries were incub ated in an anaerobic mineral salts medium that was amended with multip le electron acceptors, including manganese(IV) and Fe(III) oxides, and the concentrations of the aromatic substrates were followed over a si x- to 18-month period. Most sediment samples showed a complete loss of benzoate and 4-hydroxybenzoate within approximately two months. Benzo ate losses were partially to markedly inhibited by the addition of mol ybdate, whereas losses of 4-hydroxybenzoate were not molybdate-inhibit ed. Significant losses of aniline, 3-chlorobenzoate, and 2,4-dichlorop henoxyacetic acid were observed with many of the sediments after appro ximately 18 months. Molybdate markedly inhibited the metabolism of 3-c hlorobenzoate with all sediments, and of aniline with some sediments. Increases in free chloride, which are indicative of reductive dechlori nation, were coincident with losses of 3-chlorobenzoate and 2,4-dichlo rophenoxyacetic acid. No significant metabolism of 4-chlorobenzoate wa s apparent in any of the sediments. Overall, the results indicate that microbes with the ability to degrade at least certain aromatic compou nds are present at various sites within these environments.