Degradation of butachlor and propanil by Pseudomonas sp. strain But2 and Acinetobacter baumannii strain DT

Herbicides have been extensively used globally, resulting in severe environmental pollution. Novel butachlor-degrading Pseudomonas sp. strain But2 isolated from soil can degrade butachlor regardless of the concentration and grows without a lag phase. Specific degradation was increased at 0.01-0.1 mM, and did not change significantly at higher concentrations. During degradation, 2-chloro-N-(2,6-diethylphenyl) acetamide, 2,6-diethylaniline, and 1,3-diethylbenzene were formed, which indicated that deamination occurred. Moreover, Pseudomonas sp. strains could tolerate propanil at up to 0.8 mM. The mixed bacterial culture of Pseudomonas sp. But2 and Acinetobacter baumannii DT (a propanil-degrading bacterial strain) showed highly effective biodegradation of both butachlor and propanil in liquid media and soil. For example, under treatment with the mixed culture, the half-lives of propanil and butachlor were 1 and 5 days, respectively, whereas those for the control were 3 and 15 days. The adjuvants present in herbicides reduced degradation in liquid media, but did not influence herbicide removal from the soil. The results showed that the mixed bacteria culture is a good candidate for the removal of butachlor and propanil from contaminated soils. Pseudomonas sp. But2 utilized butachlor as the sole carbon, nitrogen and energy source, and degraded the substrate at any chemical concentration.