Complete oxidation of catechol by the strictly anaerobic sulfate-reducing Desulfobacterium catecholicum sp. nov.

Abstract

From an anaerobic enrichment culture with vanillate as substrate, a catechol-degrading lemon-shaped nonsporing sulfate-reducing bacterium, strain NZva20, was isolated in pure culture. Growth occurred in defined, bicarbonate-buffered, sulfide-reduced freshwater medium with catechol as sole electron donor and carbon source. Catechol was completely oxidized to CO2 with an average growth yield of 31 g cell dry mass per mol of catechol, corresponding to 9.5 g cell dry mass per mol of sulfate reduced. Further substrates utilized as electron donors and carbon sources were resorcinol, hydroquinone, benzoate and several other aromatic compounds, hydrogen plus carbon dioxide, formate, lactate, pyruvate, alcohols including methanol, dicarboxylic acids, acetate, propionate and higher fatty acids up to 18 carbon atoms. Instead of sulfate, sulfite, thiosulfate, dithionite or nitrate served as electron acceptors. Nitrate was reduced to ammonium. Strain NZva20 is the first bacterium in which the complete oxidation of organic substrates is linked to the ammonification of nitrate. Elemental sulfur was not utilized as electron acceptor. In the absence of an electron acceptor slow growth occurred on pyruvate or fumarate. The G+C content of the DNA of strain NZva20 was 52.4 mol%. Cytochromes were present. Desulfoviridin could not be detected. Strain NZva20 is described as type strain of a new species, Desulfobacterium catecholicum sp. nov.