ABSTRACT
Pseudomonas nitroreducens J5-1 is able to use monochlorobenzene, 1,2-dichlorobenzene, 1,3-dichlorobenzene and 1,2,4-trichlorobenzene as sole carbon and energy sources, and it differs from those 1,2,4-trichlorobenzene degrading bacteria reported in substrate utilizing characters. PCR technique was used to amplify the genes of chlorobenzene dioxygenase and dehydrogenase of J5-1, and they were named as tcbA and tcbB, respectively. Homology analysis indicated that these genes and gene products were most closely related to those of Burkholderia sp. PS12. By alignment of the amino acid sequences of the a subunits of TcbAa (from J5-1) and TecA1 (from PS12), four amino acid residues from site 307 to site 310 were found to be different (I307L, M308T, I309V, Q310E), which probably retarded the preference for the substrate 1,2,4,5-tetrachlorobenzene. Furthermore, the phylogenetic analysis of the dioxygenase alpha subunits showed that TcbAa was belong to the toluene/diphenyl subfamily, and was most closely related to the poly-chlorinated benzene dioxygenase alpha subunit.
Subject(s)
Bacterial Proteins/genetics , Chlorobenzenes/metabolism , Dioxygenases/genetics , Oxidoreductases/genetics , Pseudomonas/enzymology , Amino Acid Sequence , Bacterial Proteins/classification , Biodegradation, Environmental , Cloning, Molecular , Dioxygenases/classification , Environmental Pollutants/metabolism , Molecular Sequence Data , Oxidation-Reduction , Phylogeny , Protein Subunits/classification , Protein Subunits/genetics , Pseudomonas/genetics , Pseudomonas/metabolism , Sequence Analysis, DNA , Sequence Homology, Amino Acid , Substrate SpecificityABSTRACT
A bacterium capable of utilizing 1,2,4-trichlorobenzene as sole carbon source was isolated from the polluted soil sample. This baterium was identified as Pseudomonas nitroreducens according to its physiological & biochemical analysis and its 16S rDNA sequence (GenBank Accession No. EF107515). When the initial concentration of 1,2,4-TCB is 400 mg/L, J5-1 can achieve a maximum degradation rate of 90%. When the initial concentration of 1,2,4-TCB is 20 mg/L, the effect of degradation is the best. Degradation of 1,2,4-TCB by strain J5-1 obeys the first order dynamics. The total gene of chlorocatechol 1,2-dioxygenase was cloned from genomic DNA of J5-1.
