Affiliations: Department of Microbiology, University of
Durban-Westville, P. Bag X54001, Durban 4000, South Africa | Department of Biotechnology, Durban Institute of
Technology, P. O. Box 1334, Durban 4000, South Africa | Department of Microbiology, Faculty of Science,
Obafemi Awolowo University, Ile-Ife, Nigeria
Abstract: The innate toxicity of dichloroethenes (DCEs) and their tendency to
be reduced to vinyl chloride (VC) (a known human carcinogen) is a cause for
environmental concern. Aerobic bacteria capable of growth on cis- and
trans-DCEs as sole carbon and energy sources were isolated by enrichment
culture technique and identified to belong to the genera; Bacillus, Pseudomonas
and Acinetobacter. Axenic and mixed cultures of the bacterial isolates utilized
DCEs at concentrations above the maximum contaminant level allowable in
drinking water by the Environmental Protection Agency. Their specific growth
rate constant ranged significantly (P<0.05) between 0.346–0.552 and
0.461–0.667 d^{-1}; while the maximum specific
substrate utilization rate ranged significantly (P<0.05) between
20.01–29.79 and 31.40–42.83 nmol h^{-1} (mg of
protein)^{-1} in cis- and trans- DCE, respectively. The
optimum growth was observed at 30°C and at a pH of 7.0 with up to 96% of
the stoichiometric-expected chloride released. Serial adaptation positively
affected the growth yields and dehalogenase activities of the organisms with
multiple antibiotic patterns also demonstrated by the isolates. These findings
therefore indicated the important roles that these organisms may play in the
bioremediation of sites polluted with chlorinated ethene compounds in
Africa.
Keywords: aerobic, bioremediation, dichloroethenes, dehalogenase, polluted site
