Oxidation of dimethylsulfide to tetrathionate by Methylophaga thiooxidans sp. nov.: a new link in the sulfur cycle.
A new pathway of dimethylsulfide (DMS) metabolism was identified in a novel species of Gammaproteobacteria, Methylophaga thiooxidans sp. nov., in which tetrathionate (S(4)O(6)(2-)) was the end-product of DMS oxidation. Inhibitor evidence indicated that DMS degradation was initiated by demethylation, catalysed by a corrinoid demethylase. Thiosulfate was an intermediate, which was oxidized to tetrathionate by a cytochrome-linked thiosulfate dehydrogenase. Thiosulfate oxidation was coupled to ATP synthesis, and M. thiooxidans could also use exogenous thiosulfate as an energy source during chemolithoheterotrophic growth on DMS or methanol. Cultures grown on a variety of substrates oxidized thiosulfate, indicating that thiosulfate oxidation was constitutive. The observations have relevance to interactions among sulfur-metabolizing bacteria in the marine environment. The production of tetrathionate from an organosulfur precursor is previously undocumented and represents a potential step in the biogeochemical sulfur cycle, providing a 'shunt' across the cycle.
Boden
Rich
R
Department of Biological Sciences, University of Warwick, Coventry CV4 7AL, UK.
Kelly
Donovan P
DP
Murrell
J Colin
JC
Schäfer
Hendrik
H
D001711:Biotransformation; D055669:Ecological and Environmental Phenomena; D004785:Environmental Pollutants / Q000378:metabolism*; D008780:Methyltransferases / Q000378:metabolism; D010084:Oxidation-Reduction; D044147:Piscirickettsiaceae / Q000145:classification / Q000235:genetics / Q000378:metabolism*; D013440:Sulfides / Q000378:metabolism*; D013455:Sulfur / Q000378:metabolism*; D013776:Tetrathionic Acid / Q000378:metabolism*; D013885:Thiosulfates / Q000378:metabolism
D004785:Environmental Pollutants; D013440:Sulfides; D013885:Thiosulfates; D013455:Sulfur; D013776:Tetrathionic Acid; D008780:Methyltransferases; C004784:dimethyl sulfide