Biodegradation of nine polychlorinated biphenyls by a newly isolated bacterium, Pseudomonas aeroginosa TMU56 obtained from Iranian contaminated soils

A bacterial strain, designated TMU56, was isolated from soil contaminated with electrical transformer fluid for over 35 years. The isolate was identified as Pseudomonas aeroginosa with respect to its 16S rDNA sequence. This strain was found to grow on biphenyl, benzoate, naphthalene, 2-chlorobenzoic acid, 4- chlorobenzoic acid. The capability of this strain to degrade nine polychlorinated biphenyls in liquid medium, was evaluated. This is the first reported representative of the genus Pseudomonas capable of growing on 2,4,4’-triCB, 2,2’,5,5’-tetraCB, 2,2’,4,5,5’-pentaCB and 2,2’,4,4’,5,5’-hexaCB as a sole carbon source. Washed benzoate-grown cells were able to degrade 100% of 2-CB ; 4-CB and 2,5-diCB after 2 days of incubation, and 78%, 89%, 64%, 75%, 69% and 56% of 4,4’-diCB; 2,4-diCB; 2,4, 4’-triCB; 2,2’,5,5’-tetraCB; 2,2’,4,5,5’-pentaCB and 2,2’,4,4’,5,5’-hexaCB, respectively after 4 days of incubation.The position of the chlorine substituents on the rings strongly influenced the degradation of polychlorinated biphenyls by Pseudomonas aeroginosa TMU56.

Keywords:

Polychlorinated biphenyl , Contaminated soil , biodegradation , Pseudomonas aeroginosa TMU56