PHYSIOLOGICAL PROPERTIES OF A SULFATE-REDUCING BACTERIUM ISOLATED FROM MUNICIPAL SEWAGE SLUDGE AND ITS POSSIBLE ROLE AS A SYNTROPHIC ACIDOGEN IN THE ECOSYSTEM

摘要

Three strains of sulfate-reducing bacteria utilizing H2 as the electron donor of sulfate reduction were isolated from anaerobic digester slurry of municipal sewage sludge. The isolates were Gram-negative, non-spore- forming, motile, curved rods with a single polar flagellum. Cytochrome c3 and desulfoviridin were present. The DNA base compositions (mol% Three strains of sulfate-reducing bacteria utilizing H2 as the electron donor of sulfate reduction were isolated from anaerobic digester slurry of municipal sewage sludge. The isolates were Gram-negative, non-spore-forming, motile, curved rods with a single polar flagellum. Cytochrome c3 and desulfoviridin were present. The DNA base compositions (mol%G+C) were 59.6±0.7). The isolates used H2, formate, lactate, pyruvate, fumarate, malate, alcohols and amino acids as the electron donor for sulfate reduction. Alcohols were oxidized to corresponding monocarboxylates, and other organic compounds were to acetate. Sulfate, Three strains of sulfate-reducing bacteria utilizing H2 as the electron donor of sulfate reduction were isolated from anaerobic digester slurry ofmunicipal sewage sludge. The isolates were Gram-negative, non-spore-forming, motile, curved rods with a single polar flagellum. Cytochrome c3 and desulfoviridin were present. The DNA base compositions (mol% G+C) were 59.6±0.7. The isolates used H2, formate, lactate, pyruvate, fumarate, malate, alcohols and amino acids as the electron donor for sulfate reduction. Alcohols were oxidized to corresponding monocarboxylates, and other organic compounds were to acetate. Sulfate, sulfite and thiosulfate, but not nitrate, were used as the electron acceptor and reduced to sulfide. The isolates grew with pyruvate, fumarate, or malate as the energy source in the absence of oxidized sulfur compounds. yruvate was oxidized to acetate with the production of formate and H2. Fumarate and malate were oxidized to acetate, and the oxidation was coupled with the reduction of fumarate or malate to succinate. From the morphological and physiological properties, the isolates were considered to belong to a Desulfovibrio sp. In association with Methanobacterium formicicum as a hydrogen-consuming partner, one of the isolates could also grow in the absence of oxidized sulfur compounds by utilizing organic substrates other than pyruvate, malate and fumarate. In the coculture of the isolate and the methanogen, all the organic compounds other than malate and fumarate, which could serve as the electron donor for sulfate reduction in the pure culture of isolates, were syntrophically oxidized with the production of methane. These results indicate that the isolates of sulfate-reducing bacteria can play a role as a syntrophic degrader of a wide range of organic compounds in the methanogenic sewage sludge devoid of sulfate.