ANALYSIS OF DIESEL SPILL BIOREMEDIATION BY BACTERIAL ISOLATES IN BATCH CULTURE USING MONOD AND HALDANE KINETIC MODEL

Abstract

The unintended oil spills from oil tankers, transportation and storage facilities, leads to petroleum hydrocarbon pollution that causes adverse effects on the air, water and soil environment. Bioremediation using indigenous microorganisms has become a promising tool for effective mineralization of toxic contaminants into harmless end products. In this study, bioremediation of petroleum contaminated soil was carried out in a batch scale using Staphylococcus, Pseudomonas, Micrococcus, Escherichia, Acinetobacter, Bacillus, Corynebacterium, Salmonella and Klebsiella species, all isolated from petroleum hydrocarbon contaminated soil. The effect of 1 to 10% v/v diesel concentrations on the growth and biodegradation rate of all selected nine isolates was studied and specific growth rates (μh -1) were calculated. The initial rate of growth and biodegradation of nine isolates increased correspondingly with the diesel concentration up to 5% (v/v), but further increase in diesel concentration resulted in a slight decrease in the rate of biodegradation. Diesel is known to be an inhibitory substrate. Both Monod and Haldane kinetic models were useful for the evaluation of the growth kinetic parameters (μmax, Ks, Ki). It was found that the Monod model was able to express the growth parameters up to 5% v/v diesel. However, Haldane model effortlessly fitted with the experimental data for increase in the diesel i.e. over 6 % v/v diesel. These results showed that the diesel oil degraders were able to utilize a considerably high concentration of diesel and could be very effective in diesel biodegradation for restoration of contaminated sites.