Abstract

ACTIVITY ASSAY OF BACTERIAL MIXED CULTURE IN BIOLOGICAL TREATMENT OF ORGANOCHLOROPESTICIDES

Iman H. Gatea*, Eman H. Khudhair, Amina G. A. Bid, Amal A. Halob and S. Kh. Maied

Abstract

Some pesticides are readily degraded by microorganisms; others have proven to be recalcitrant. A diverse group of bacteria, including members of the genera Alcaligenes, Flavobacterium, Pseudomonas and Rhodococcus, metabolize pesticides. Microbial degradation depends not only on the presence of microbes with the appropriate degradative enzymes, but also on a wide range of environmental parameters. In this research two bacterial isolates defined consortium with Propachlor biodegradation capacity, were isolated from soil samples from pesticides contaminated site. These consortia: Streptomyces sp.Y7and Rhodococcus sp.S3 produced a significant increment of the specific degradation activity compared to the individual culture with 20 mg L-1 of Propachlor as the only carbon source, consortium of Streptomyces spY7 and Rhodococcus spS3 were able to grow with different concentration of Propachlor. The microorganisms present in the special growth medium provided with Propachlor as a sole carbon source were found to possess the ability to degrade 84% of it after 48 h. of incubation at 30°C with shaking at 120 rpm and optimum pH was7 and 35 mg L-1of pesticide was the favorable concentration. Therefore the selected bacterial isolates could be considered one of the most promising bacterial groups for COP biodegradation in contaminated environment.

Keywords: Chlorinated organopesticides; Bacteria; Degradation, Propachlor, Contaminated soils.