Isolation and Characterization of Metolachlor Degrading Bacteria

Three bacterial isolates (MB1-MB3) capable of degrading metolachlor were isolated from digested sewage sludge, laboratory soil incubated under aerobic condition and metolachlor acclimated field soil. There was no variation in cultural, morphological and biochemical characteristics of the three isolates. They were identified as fluorescent Pseudomonas sp. As the isolates failed to produce pyocyanin, P. aeruginosa was ruled out. The production of green fluorescence under UV-light and other biochemical characteristics confirmed their classification as fluorescent Pseudomonas sp. The MB1 isolate from sewage eludge could degrade up to 85.6% metolachlor when incubated for 20 d at 10 μg mL−1 level in a minimal salt medium supplemented with 0.05% mannitol as additional carbon source. MB2 and MB3 degraded metolachlor up to 70 and 70.7%, respectively, when incubated at 20 ug mL−1 level for 20 d in the minimal salt medium. The MB3 isolate from field soil degraded metolachlor and produced four metabolites, two of which are new metabolites being reported in this study.