Biodegradation of propanil by Acinetobacter baumannii DT in a biofilm-batch reactor and effects of butachlor on the degradation process.

Abstract

The herbicide, propanil, has been extensively applied in weed control, which causes serious environmental pollution. Acinetobacter baumannii DT isolated from soil has been used to determine the degradation rates of propanil and 3,4-dichloroaniline by freely suspended and biofilm cells. The results showed that the bacterial isolate could utilize both compounds as sole carbon and nitrogen sources. Edwards's model could be fitted well to the degradation kinetics of propanil, with the maximum degradation of 0.027±0.003mM h-1. The investigation of the degradation pathway showed that A. baumannii DT transformed propanil to 3,4-dichloroaniline before being completely degraded via the ortho-cleavage pathway. In addition, A. baumannii DT showed high tolerance to butachlor, a herbicide usually mixed with propanil to enhance weed control. The presence of propanil and butachlor in the liquid media increased the cell surface hydrophobicity and biofilm formation. Moreover, the biofilm reactor showed increased degradation rates of propanil and butachlor and high tolerance of bacteria to these chemicals. The obtained results showed that A. baumannii DT has a high potential in the degradation of propanil.