Desulfurization of alkylated forms of both dibenzothiophene and benzothiophene by a single bacterial strain.
Thirty-five bacterial strains capable of converting dibenzothiophene into 2-hydroxybiphenyl were isolated. Among them Rhodococcus erythropolis KA2-5-1 was chosen for further characterization because of its ability to retain high desulfurization activity stably. PCR cloning and DNA sequencing of a KA2-5-1 genomic DNA fragment showed that it was practically identical with dszABC genes from Rhodococcus sp. IGTS8, a representative carbon-sulfur-bond-targeted dibenzothiophene-degrading bacterium. KA2-5-1 desulfurized a variety of alkyl dibenzothiophenes through the specific cleavage of their C-S bonds. In addition, unexpectedly, KA2-5-1 also attacked alkyl benzothiophenes in a C-S-bond-targeted fashion. The purified monooxygenase, encoded by dszC of KA2-5-1, converted benzothiophene and dibenzothiophene into benzothiophene sulfone and dibenzothiophene sulfone, respectively, with the aid of an NADH-dependent oxidoreductase. This result raises the possibility that the same enzymatic step may be involved in desulfurization of alkylated forms of both dibenzothiophene and benzothiophene in KA2-5-1 cells.
Kobayashi
M
M
Bio-Refining Process Laboratory, Advanced Technology and Research Institute, Petroleum Energy Center, 1900 Sodeshi-Cho, Shimizu-Shi, 424-0037, Shizuoka, Japan.
Onaka
T
T
Ishii
Y
Y
Konishi
J
J
Takaki
M
M
Okada
H
H
Ohta
Y
Y
Koizumi
K
K
Suzuki
M
M
D000478:Alkylation; D001673:Biodegradation, Environmental; D008401:Gas Chromatography-Mass Spectrometry; D012240:Rhodococcus / Q000235:genetics / Q000254:growth & development / Q000302:isolation & purification / Q000378:metabolism*; D012988:Soil Microbiology; D013876:Thiophenes / Q000378:metabolism*
D013876:Thiophenes; C088015:benzothiophene; C016366:dibenzothiophene