African Journal of Biotechnology Vol. 5 (20), pp. 1913-1917, 16 October 2006   

ISSN 1684–5315 © 2006 Academic Journals        

Full Length Research Paper

Aerobic cometabolic degradation of cis- and trans-dichloroethene by a consortium of bacteria isolated from contaminated sites in Africa

Ademola O. Olaniran^1,2*, Dorsamy Pillay^1,3 and Balakrishna Pillay¹

¹Department of Microbiology, Faculty of Science and Agriculture, University of KwaZulu-Natal (Westville Campus), Private Bag X54001, Durban 4000, Republic of South Africa.

²Department of Microbiology, Faculty of Science, Obafemi Awolowo University, Ile-Ife, Nigeria.

³Department of Biotechnology, Faculty of Engineering, Science and Built Environment, Durban Institute of Technology, P. O. Box 1334, Durban 4000, Republic of South Africa.

*Corresponding authors E-mail: olanirana@ukzn.ac.za     Fax: + 27 31 260 7809.

Accepted 27 March, 2006

Biodegradation of dichloroethenes (DCEs) to innocuous products such as ethene and carbondioxide is often a limiting factor in the use of reductive dechlorination as an approach for the remediation of chloroethene-contaminated sites. In this study, the effect of some water-soluble, non-toxic and non-flammable substrates on the biodegradation of DCEs by a mixed culture of aerobic bacteria isolated from contaminated sites in Africa was investigated. A general increase of 2.13 – 22.18% and 0.39 – 12.61% in the amount of cis- and trans-DCE degraded, respectively, was observed in the presence of the different primary substrates. Glucose had the most significant effect resulting in 91.68% removal of cis-DCE and 86.98% removal of trans-DCE after 7 days. These values corresponded to 22.18 and 12.61% above the amount of cis- and trans-DCE degraded, respectively, in the absence of primary substrates. Results from this study indicate that the biodegradation of both compounds is enhanced by cometabolism. This finding is significant for active bioremediation systems, since the addition of these substrates to groundwater has several advantages over other cometabolic electron donors presently in use.

Key words:     Bacterial consortium, biodegradation, cometabolism, dichloroethene.