title: Anaerobic elemental sulfur reduction by fungus Fusarium oxysporum.
abstract: Reduction of inorganic sulfur compounds by the fungus Fusarium oxysporum was examined. When transferred from a normoxic to an anoxic environment, F. oxysporum reduced elemental sulfur to hydrogen sulfide (H2S). This reaction accompanied fungal growth and oxidation of the carbon source (ethanol) to acetate. Over 2-fold more of H2S than of acetate was produced, which is the theoretical correlation for the oxidation of ethanol to acetate. NADH-dependent sulfur reductase (SR) activity was detected in cell-free extracts of the H2S-producing fungus, and was found to be up-regulated under the anaerobic conditions. On the other hands both O2 consumption by the cells and cytochrome c oxidase activity by the crude mitochondrial fractions decreased. These results indicate that H2S production involving SR was due to a novel dissimilation mechanism of F. oxysporum, and that the fungus adapts to anaerobic conditions by replacing the energy-producing mechanism of O2 respiration with sulfur reduction.
authors.affiliation: Graduate School of Life and Environmental Sciences, University of Tsukuba, Japan.
authors.forename: Tsuyoshi
authors.initials: T
authors.lastname: Abe
authors.forename: Takayuki
authors.initials: T
authors.lastname: Hoshino
authors.forename: Akira
authors.initials: A
authors.lastname: Nakamura
authors.forename: Naoki
authors.initials: N
authors.lastname: Takaya
mesh_terms: D000085:Acetates / Q000378:metabolism; D000693:Anaerobiosis; D002474:Cell-Free System; D003576:Electron Transport Complex IV / Q000378:metabolism; D000431:Ethanol / Q000378:metabolism; D005670:Fusarium / Q000378:metabolism*; D006862:Hydrogen Sulfide / Q000378:metabolism; D008928:Mitochondria / Q000378:metabolism; D010084:Oxidation-Reduction; D010088:Oxidoreductases / Q000378:metabolism; D010101:Oxygen Consumption; D013455:Sulfur / Q000378:metabolism*
chemical_list: D000085:Acetates; D000431:Ethanol; D013455:Sulfur; D010088:Oxidoreductases; C074883:polysulfide reductase; D003576:Electron Transport Complex IV; D006862:Hydrogen Sulfide