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Title: Aerobic microbial cometabolism of benzothiophene and 3-methylbenzothiophene

Journal Article · · Applied and Environmental Microbiology; (United States)
OSTI ID:5675952
 [1];  [2]
  1. Univ. of Alberta, Edmonton (Canada)
  2. Stanford Univ., CA (United States)

A culture enriched by growth on 1-methylnaphthalene was used to study the aerobic biotransformations of benzothiophene and 3-methylbenzothiophene. Neither of these sulfur heterocyclic compounds would support growth, but they were transformed by the culture growing on 1-methylnaphthalene or glucose or peptone. Cometabolism of benzothiophene yielded benzothiophene-2,3-dione, whereas that of 3-methylbenzothiophene yielded 3-methylbenzothiophene sulfoxide and the corresponding sulfone. The identities of the dione and sulfone were verified by comparison with authentic standards. The identity of the sulfoxide was surmised from gas chromatography-mass spectrometry and gas chromatography-Fourier transform infrared spectroscopy results. Oxidation preferentially occurred at carbons 2 and 3 in benzothiophene, but when carbon 3 was substituted with a methyl group, as in 3-methylbenzothiophene, the sulfur atom was oxygenated. The predominant microorganism in the enrichment culture was a Pseudomonas strain, designated BT1, which mineralized aromatic but not aliphatic hydrocarbons. This isolate cometabolized benzothiophene and 3-methyl-benzothiophene. There was no evidence that it could metabolize 3-methylbenzothiophene sulfone. When 3-methylbenzothiophene was added to Prudhoe Bay crude oil, the sulfur heterocycle was oxidized to its sulfoxide and sulfone by strain BT1 as it grew on the aromatic hydrocarbons in the crude oil. Benzothiophene-2,3-dione was found to be chemically unstable when incubated with Prudhoe Bay crude oil. Thus its formation from benzothiophene in the presence of crude oil could not be determined.

OSTI ID:
5675952
Journal Information:
Applied and Environmental Microbiology; (United States), Vol. 57:4; ISSN 0099-2240
Country of Publication:
United States
Language:
English