Partial characterization of degradative plasmids of gram-negative bacilli from polychorinated biphenyls (PCBs) contaminated soil samples in Lagos, Nigeria.

¹Dele-Osibanjo Taiwo A.^* and ²Daini O. A.

¹Department of Biochemistry, Olabisi Onabanjo University, Ago-Iwoye, Ogun State, Nigeria.

²Department of Biochemistry, International University of Kampala, Uganda.

Corresponding Author’s E-mail:osibanjotaiwo@yahoo.com; 

Tel: +2347034590749; +2348076454821.

Accepted 30 January, 2013

Abstract

The research was aimed at finding out a cost-effective and efficient means of eliminating the hazardous contaminants, polychlorinated biphenyls (PCBs) from the environment. A total of thirty-six (36) soil samples were collected from the transformer dumping site of the Power Holding Company of Nigeria (PHCN) at Ijora-Olopa in Lagos State, Nigeria. Through standard microbiological isolation and identification techniques, the micro-organisms degrading these compounds were found to be bacteria, of which only twenty-two (22) strains were Gram-negative, belonging to the genera; Eschericia, Klebsiella and Pseudomonas respectively. Appropriate Plasmid isolation and Agarose gel electrophoresis techniques revealed that only fifteen (15)  out of the twenty-two (22) gram-negative strains harboured plasmids with sizes ranging from 1000 – 1738 base pairs (bp). Transformation experiments further revealed that out of the fifteen (15) strains which harboured plasmids, only ten (10) strains were able to transfer their degradative genes which are plasmid-borne to a recipient strain. The transformant plasmid sizes ranged from 1202 – 1738 base pairs (bp) respectively. The results of the study indicates that the degradative genes for polychlorinated biphenyls are plasmid-borne in some bacteria and these plasmids can be effectively transformed into appropriate, non-pathogenic, and ubiquitous recipient strains, thus facilitating the large-scale degradation of these chemicals.

Keywords: Polychlorinated Biphenyls (PCBs), Plasmids, Degradative genes, ubiquitous.