Plasmids of the Chlorophenoxyacetic-Acid Degradation of Bacteria of the Genus Raoultella

Members of the Raoultella planticola species isolated from soils contaminated with chemical waste were able to use 2,4-dichlorophenoxyacetic/2,4,5-trichlorophenoxyacetic acid as the sole source of carbon and energy. It was found that cells of strains 33-4ch, 36D, and 36T contained plasmids that were designated as pRP33-4ch, pRP36D and pRP36T, respectively. Restriction fragment length polymorphism (RFLP) analysis showed that pRP33-4ch and pRP36T were probably the same plasmid, while pRP36D contained additional fragments in the restriction profiles. Plasmid elimination showed that the genes for the degradation of chlorophenoxyacetic acids have extrachromosomal localization. Polymerase chain reaction (PCR) demonstrated the absence in the genomes of the studied strains of known initiation genes (tfdA and tftA) for the conversion of chlorophenoxyacetic acids. The identified intermediate metabolites (chlorophenoxyacetic and phenoxyacetic acids and 2-keto-3-methylmuconic semialdehyde) indicated that the strains 33-4ch, 36D, and 36T perform complete dechlorination of the aromatic ring of the substrate with its subsequent meta-cleavage.