A novel biphenyl-degrading bacterial strain LA-4 was isolated from activated sludge. It was identified as Dyella ginsengisoli according to phylogenetic similarity of 16S rRNA gene sequence. This isolate could utilize biphenyl as sole source of carbon and energy, which degraded over 95 mg/L biphenyl within 36 h. The major metabolites formed from biphenyl, such as 2-hydroxy-6-oxo-6-phenylhexa-2,4-dienoic acid (HOPDA) and benzoic acid, were identified by LC-MS. The crude cell extract of strain LA-4 exhibited the activity of 2,3-dihydroxybiphenyl 1,2-dioxygenase (2,3-DHBD) and the kinetic parameters were Km= 26.48 μmol/L and Vmax= 8.12 μmol/mg protein. A conserved region of the biphenyl dioxygenase gene bphA1 of strain LA-4 was amplified by PCR and confirmed by DNA sequencing. 相似文献
The aim of this study is to analyze the effect of salinity on polycyclic aromatic hydrocarbons (PAHs) biodegradation, community structure and naphthalene dioxygenase gene (ndo) diversity of a halophilic bacterial consortium with the denaturing gradient gel electrophoresis (DGGE) approach. The consortium was developed from oil-contaminated saline soil after enrichment for six times, using phenanthrene as the substrate. The prominent species in the bacterial consortium at all salinities were identified as halophilic bacteria Halomonas, Alcanivorax, Marinobacter, Idiomarina, Martelella and uncultured bacteria. The predominant microbes gradually changed associating with the saline concentration fluctuations ranging from 0.1% to 25% (w/v). Two ndo alpha subunits were dominant at salinities ranging from 0.1% to 20%, while not been clearly detected at 25% salinity. Consistently, the biodegradation occurred at salinities ranging from 0.1% to 20%, while no at 25% salinity, suggesting the two ndo genes played an important role in the degradation. The phylogenetic analysis revealed that both of the two ndo alpha subunits were related to the classic nah-like gene from Pseudomonas stutzeri AN10 and Pseudomonas aeruginosa PaK1, while one with identity of about 82% and the other one with identity of 90% at amino acid sequence level. We concluded that salinity greatly affected halophilic bacterial community structure and also the functional genes which were more related to biodegradation.
The process of benzoate degradation by strain Rhodococcus opacus 1CP after a five-year dormancy was investigated and its peculiarities were revealed. The strain was shown to be capable of growth on benzoate at a concentration of up to 10 g L?1. The substrate specificity of benzoate dioxygenase (BDO) during the culture growth on a medium with a low (200–250 mg L?1) and high (4 g L?1) concentration of benzoate was assessed. BDO of R. opacus 1CP was shown to be an extremely narrow specificity enzyme. Out of 31 substituted benzoates, only with one, 3-chlorobenzoate, its activity was higher than 9% of that of benzoate. Two dioxygenases, catechol 1,2-dioxygenase (Cat 1,2-DO) and protocatechuate 3,4-dioxygenase (PCA 3,4-DO), were identified in a cell-free extract, purified and characterized. The substrate specificity of Cat 1,2-DO isolated from cells of strain 1CP after the dormancy was found to differ significantly from that of Cat 1,2-DO isolated earlier from cells of this strain grown on benzoate. By its substrate specificity, the described Cat 1,2-DO was close to the Cat 1,2-DO from strain 1CP grown on 4-methylbenzoate. Neither activity nor inhibition by protocatechuate was observed during the reaction of Cat 1,2-DO with catechol, and catechol had no inhibitory effect on the reaction of PCA 3,4-DO with protocatechuate. 相似文献
Bacteria and bacterial communities in sites contaminated with polychlorinated biphenyls have been extensively studied in the past decades. However, there are still major gaps in the knowledge of environmental processes, especially in the behavior of previously described bacteria in vitro, their real degradation abilities and the enzymes that are involved in the degradation processes. 相似文献
