Bioremediation of Petroleum Oil in Contaminated Environment

Abstract

The present work aims to use microorganisms in removing crude petroleum oil from contaminated environment. Therefore one hundred and thirty six isolates from contaminated soil and water were screened for their capability to degrade crude oil. The most potent isolates for the petroleum crude oil degradation were identified as Alcaligenes faecalis, Microbacterium oxydans and Microbacterium Paraoxydans, and were isolated from Tebbin, Al Kanater and Agiba, respectively. The optimization of cultural conditions to maximize the efficiency of petroleum crude oil bioremediation by the three bacterial strains were investigated. The mineral salt medium was used, pH 7.5, inoculum size at 0.8 % , agitation at 100 rpm, temperature 30°C and 30 days of incubation showed the highest degradation of crude oil by the three bacterial strains. Ammonium sulphate as a sole N-source and crude oil as a sole C-sources were more suitable for crude oil degradation at concentrations of 0.2 % and 1.0 %, respectively. The immobilization of cells in Alginate beads and their viability were studied. For the degradation efficiency of crude oil by free and immobilized bacterial cells in individual and consortium forms, results showed that the degradation ability by the immobilized bacterial cells either individually or in combination increased clearly relative to that by the free ones. For the individual immobilized strains, the best degradation efficiency was obtained by M. oxydans followed by A. faecalis. The degradation efficiency of M. Paraoxydans was the lowest one. For the immobilized consortium, results showed that consortium 1 (A. faecalis and M. oxydans) followed by consortium 3 (M. oxydans with M. Paraoxydans) with degradation percentages 76 and 68 %, respectively. Consortium 2 (A. faecalis and M. Paraoxydans) and Consortium 4