title: Analysis of the dibenzothiophene metabolic pathway in a newly isolated Rhodococcus spp.
abstract: Out of 17 samples collected from diverse environments, 110 bacterial isolates of varied characteristics were screened for their dibenzothiophene-desulphurizing activity. A single isolate, Eu-32, originating from a soil sample taken from the roots of a eucalyptus tree, displayed dibenzothiophene-desulphurizing activity. This isolate metabolized dibenzothiophene to 2-hydroxybiphenyl (2-HBP), as detected by HPLC, and was also able to use other organic sulphur compounds as a sole sulphur source. Based on morphological, biochemical and molecular studies, it was found that the organism belongs to the genus Rhodococcus, with a maximum of 95% identity to species in this genus for the partial sequence of the 16S rRNA gene. Isolate Eu-32 could desulphurize 0.2 mM dibenzothiophene to 2-HBP in 72 h at a temperature of 30 degrees C and pH 7.0. The structure and molecular mass of metabolites produced from dibenzothiophene desulphurization were identified by GC-MS, and two sulphur-free products, 2-HBP and biphenyl, were detected in ethyl acetate extract. It was concluded that isolate Eu-32 is a unique desulphurizing biocatalyst that desulphurizes dibenzothiophene through an extended, sulphur-specific degradation pathway with the selective cleavage of C-S bonds.
authors.affiliation: Industrial Biotechnology Division, National Institute for Biotechnology and Genetic Engineering, Faisalabad, Pakistan.
authors.forename: Nasrin
authors.initials: N
authors.lastname: Akhtar
authors.forename: Muhammad A
authors.initials: MA
authors.lastname: Ghauri
authors.forename: Munir A
authors.initials: MA
authors.lastname: Anwar
authors.forename: Kalsoom
authors.initials: K
authors.lastname: Akhtar
mesh_terms: D001713:Biphenyl Compounds / Q000737:chemistry / Q000378:metabolism; D002851:Chromatography, High Pressure Liquid; D004269:DNA, Bacterial / Q000032:analysis / Q000235:genetics; D005052:Eucalyptus / Q000382:microbiology; D008401:Gas Chromatography-Mass Spectrometry; D053858:Metabolic Networks and Pathways; D010802:Phylogeny; D018517:Plant Roots / Q000382:microbiology; D012336:RNA, Ribosomal, 16S / Q000032:analysis / Q000235:genetics; D012240:Rhodococcus / Q000145:classification / Q000302:isolation & purification* / Q000502:physiology*; D017422:Sequence Analysis, DNA; D012988:Soil Microbiology; D013045:Species Specificity; D013876:Thiophenes / Q000737:chemistry / Q000378:metabolism*
chemical_list: D001713:Biphenyl Compounds; D004269:DNA, Bacterial; D012336:RNA, Ribosomal, 16S; D013876:Thiophenes; C010574:biphenyl; C004369:2-phenylphenol; C016366:dibenzothiophene