Bioremediation of Certain Organophosphorus Pesticides by Two Biofertilizers, Paenibacillus( Bacillus) polymyxa (Prazmowski ) and Azospirillum lipoferum (Beijerinck)

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Continuous and excessive use of organophosphorus compounds has led to thecontamination of water and soil ecosystems. The degradation of organophosphorusinsecticides, chlorpyrifos, chlorpyrifos- methyl, cyanophos and malathion in mineral saltsmedia were studied. The effect of additional biofertilizers, singly or combined withorganic amendments, on chlorpyrifos and cyanophos degrading activity in soil wereinvestigated. Paenibacillus ( Bacillus) polymyxa (Prazmowski ) and Azospirillum lipoferum(Beijerinck) were found to degrade the organophosphorus insecticides, chlorpyrifos,chlorpyrifos- methyl, cyanophos and malathion in mineral salts media as a carbon andphosphorus source. Paenibacillus ( Bacillus) polymyxa (Prazmowski ) appeared to be moreeffective than Azospirillum lipoferum in degrading all the tested organophosphatepesticides in mineral salts media. The half-life values (t1/2) of chlorpyrifos, chlorpyrifos –methyl , cyanophos and malathion were found to be undetectable , undetectable , 2.4, andundetectable days in mineral salts media inoculated by Paenibacillus ( Bacillus) polymyxa(Prazmowski ),while they reached 1.6, 0.1, 5.2, and 0.8 days by Azospirillum lipoferum(Beijerinck) compared to 4.4, 1.8, 8.8, and 1.4 days in non-inoculated mineral salts media.Chlorpyrifos and cyanophos degraded in soil samples inoculated by Azospirillumlipoferum (Beijerinck) plus peat- moss more rapidly than in the other treatments. Dualinoculation of Azospirillum lipoferum (Beijerinck) and Paenibacillus ( Bacillus) polymyxa(Prazmowski ) improved the rate of degradation of chlorpyrifos and cyanophos in soil.Azospirillum lipoferum (Beijerinck) appeared to be more effective than Paenibacillus (Bacillus) polymyxa (Prazmowski ) in degrading soil-applied chlorpyrifos and cyanophos.These results highlight the potential of these bacteria to be used in the clean- up ofcontaminated pesticides – waste in the environment.