Assessment of detoxification of malathion by Pseudomonas isolates

Malathion degrading bacteria were isolated from a soil sample. Growth of mono and co-cultured strains of Pseudomonas in media containing the organophosphate insecticide, malathion as sole source of carbon was employed to assess degradability of the bacteria. On the seventh day of inoculation, bacteria free culture fluids as well as un-inoculated fluids were analyzed by gas chromatography and mass spectrometry (GC-MS). Malathion was not detected in the cell free culture fluids, instead four degradation products namely phoratoxon sulfone, malaoxon, butanedioic acid and ethyl methyl-methyl phosphonate made their appearance in the cultivation culture. All of the three strains used in this study, appeared efficient in degrading the insecticide especially in co-culturing conditions. These bacteria are promising for detoxifying the insecticide contaminated soils.