Degradation of hydroxyhydroquinone by the strictly anaerobic fermenting bacterium Pelobacter massiliensis sp. nov.

Abstract

A new rod-shaped, gram-negative, non-sporeforming, strictly anaerobic bacterium (strain HHQ7) was enriched and isolated from marine mud samples with hydroxyhydroquinone (l,2,4-trihydroxybenzene) as sole substrate. Strain HHQ7 fermented hydroxyhydroquinone, pyrogallol (1,2,3-trihydroxybenzene), phloroglucinol (1,3,5-trihydroxybenzene) and gallic acid (3,4,5-trihydroxybenzoate) to 3 mol acetate (plus 1 mol CO2 in the case of gallic acid) per mol of substrate. Resorcinol accumulated intermediately during growth on hydroxyhydroquinone. No other aliphatic or aromatic substrates were utilized. Sulfate, sulfite, sulfur, nitrate, and fumarate were not reduced with hydroxyhydroquinone as electron donor. The strain grew in sulfide-reduced mineral medium supplemented with 7 vitamins. The DNA base ratio was 59% G + C. Strain HHQ7 is classified as a new species of the genus Pelobacter, P. massiliensis. Experiments with dense cell suspensions of hydroxyhydroquinone- and pyrogallol-grown cells showed different kinetics of hydroxyhydroquinone and pyrogallol degradation, as well as different patterns of resorcinol accumulation, indicating that these substrates are metabolized by different transhydroxylation reactions.