title: Biodegradation of benzene, toluene, ethylbenzene, and o-xylene by the bacterium Mycobacterium cosmeticum byf-4.
abstract: A new strain Mycobacterium cosmeticum byf-4 able to simultaneously degrade benzene, toluene, ethylbenzene, and o-xylene (BTE(o-)X) compounds has been isolated and identified previously in our laboratory. We further report here the extent of degradation of every BTE(o-)X component, and unravel the initial mechanism involved in BTE(o-)X degradation. This organism efficiently degrades all the BTE(o-)X components when these compounds are added either individually or as a composite mixture, and has a preference for toluene followed by benzene, ethylbenzene and then o-xylene. The significantly high carbon recovery indicated that the predominant fate for BTE(o-)X compounds was mineralization and incorporation into cell materials. The presence of BTE compounds in binary or ternary mixtures consistently had a negative effect on o-xylene degradation. The initial steps involved in the degradation of BTE(o-)X were investigated by isolation of metabolites and assay of reverse transcription RT-PCR. Isolation of metabolites suggested that the BTE(o-)X compounds were initially converted by a dioxygenase to their respective catechols. The gene sequence of the PCR amplicons revealed that this isolate contained a 454-bp toluene dioxygenase (TOD) fragment. The BTE(o-)X-specific induction of the genes encoding TOD was confirmed by RT-PCR analysis. These results indicated that TOD was possibly responsible for the initial steps of BTE(o-)X catabolism in M. cosmeticum byf-4.
authors.affiliation: School of Biological and Environmental Engineering, Zhejiang University of Technology, Zhaohui, Hangzhou 310032, China.
authors.forename: Lili
authors.initials: L
authors.lastname: Zhang
authors.forename: Chao
authors.initials: C
authors.lastname: Zhang
authors.forename: Zhuowei
authors.initials: Z
authors.lastname: Cheng
authors.forename: Yanlai
authors.initials: Y
authors.lastname: Yao
authors.forename: Jianmeng
authors.initials: J
authors.lastname: Chen
mesh_terms: D001483:Base Sequence; D001554:Benzene / Q000032:analysis / Q000378:metabolism*; D001555:Benzene Derivatives / Q000032:analysis / Q000378:metabolism*; D001673:Biodegradation, Environmental; D004785:Environmental Pollutants / Q000032:analysis / Q000378:metabolism*; D008969:Molecular Sequence Data; D009161:Mycobacterium / Q000378:metabolism*; D014050:Toluene / Q000032:analysis / Q000378:metabolism*; D014992:Xylenes / Q000032:analysis / Q000378:metabolism*
chemical_list: D001555:Benzene Derivatives; D004785:Environmental Pollutants; D014992:Xylenes; D014050:Toluene; D001554:Benzene; C004912:ethylbenzene