Microbial Degradation of Oil Contaminated Environments and Application of Bacteria in the Digestion of Cotton Seed Oil and Subsequent Removal of Gossypol





Bio-remediation is the use of biological (mostly microbiological) means to restore an environment altered by contaminants e.g. industrial waste pollutants. In heavily polluted environments, already present native organisms that are well suited to the sub-surface environment undertake a natural breakdown process of chemical pollutants. The goal of this study was to screen for fatty acid mineralizing microorganisms from a waste water reservoir of Menengai Oil Refinery (MOR) in Nakuru, Kenya. MOR manufactures toilet, laundry, and other types of bar soap. The hypothesis was that MOR waste water contained remnant fatty acids (stearic, linoleic, etc.) and other lipid constituents from the saponification process and that the waste water treatment reservoir would harbour lipid metabolizing bacteria.


The specific objectives were to (a) isolate pure bacterial colonies from MOR waste water, and (b) use MOR waste water isolates to breakdown cottonseed oil fatty acids and remove gossypol – a polyphenolic compound that causes infertility hence rendering the oil unfit for human consumption. MOR waste water samples were plated on Luria-Bertani agar plates and incubated at 37"C for 24 hours. Single bacterial colonies were picked and sub-cultured in LB broth to generate more of the colony cells. The bacteria were then transferred to a volume of autoclaved MOR waste water sample to study their effect.


Pure MOR bacterial colonies were inoculated in minimum media broth containing cottonseed oil as sole substrate. The bacterial colonies were found to be active against oil components of MOR waste water and cottonseed oil but mild against gossypol. In conclusion, the isolated MOR waste water bacteria colonies may contain enzymes that can break down organic oils and therefore these bacteria can be further developed, studied and used to cheaply and efficiently bioremediate oil contaminated environments.

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