title: Aerobic biodegradation of 2,2'-dithiodibenzoic acid produced from dibenzothiophene metabolites.
abstract: Dibenzothiophene is a sulfur heterocycle found in crude oils and coal. The biodegradation of dibenzothiophene through the Kodama pathway by Pseudomonas sp. strain BT1d leads to the formation of three disulfides: 2-oxo-2-(2-thiophenyl)ethanoic acid disulfide, 2-oxo-2-(2-thiophenyl)ethanoic acid-2-benzoic acid disulfide, and 2,2'-dithiodibenzoic acid. When provided as the carbon and sulfur source in liquid medium, 2,2'-dithiodibenzoic acid was degraded by soil enrichment cultures. Two bacterial isolates, designated strains RM1 and RM6, degraded 2,2'-dithiodibenzoic acid when combined in the medium. Isolate RM6 was found to have an absolute requirement for vitamin B12, and it degraded 2,2'-dithiodibenzoic acid in pure culture when the medium was supplemented with this vitamin. Isolate RM6 also degraded 2,2'-dithiodibenzoic acid in medium containing sterilized supernatants from cultures of isolate RM1 grown on glucose or benzoate. Isolate RM6 was identified as a member of the genus Variovorax using the Biolog system and 16S rRNA gene analysis. Although the mechanism of disulfide metabolism could not be determined, benzoic acid was detected as a transient metabolite of 2,2'-dithiodibenzoic acid biodegradation by Variovorax sp. strain RM6. In pure culture, this isolate mineralized 2,2'-dithiodibenzoic acid, releasing 59% of the carbon as carbon dioxide and 88% of the sulfur as sulfate.
authors.affiliation: Department of Biological Sciences, University of Alberta, Edmonton, T6G 2E9 Alberta, Canada.
authors.forename: Rozlyn F
authors.initials: RF
authors.lastname: Young
authors.forename: Stephanie M
authors.initials: SM
authors.lastname: Cheng
authors.forename: Phillip M
authors.initials: PM
authors.lastname: Fedorak
mesh_terms: D000332:Aerobiosis; D001673:Biodegradation, Environmental; D042621:Comamonadaceae / Q000235:genetics / Q000254:growth & development / Q000302:isolation & purification / Q000378:metabolism*; D004269:DNA, Bacterial / Q000032:analysis; D004220:Disulfides / Q000737:chemistry / Q000378:metabolism*; D008969:Molecular Sequence Data; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D012240:Rhodococcus / Q000235:genetics / Q000254:growth & development / Q000302:isolation & purification / Q000378:metabolism*; D017422:Sequence Analysis, DNA; D013876:Thiophenes / Q000737:chemistry / Q000378:metabolism*
chemical_list: D004269:DNA, Bacterial; D004220:Disulfides; D012336:RNA, Ribosomal, 16S; D013876:Thiophenes; C016366:dibenzothiophene