The biodegradation of acetochlor in solution and soil and improvements in the growth of maize seedlings by a phosphatesolubilizing bacterial strain were investigated in this research. The strain Bacillus sp. ACD-9 optimally degraded acetochlor at pH 6.0 and 42 °C in solution. And acetochlor with an initial concentration of 30 mg/L was efficiently (> 60%) degraded by the strain after 2 days in solution. Acetochlor biodegradation and the resulting beneficial products were also identified by LC-MS, and the probable degradation products of acetochlor and two kinds of plant growth hormones, namely, 2-chloro-N-(2-methyl-6-ethylphenyl) acetamide (CMEPA), indoleacetic acid (IAA), and zeatin, were detected from the fermentation broth of strain ACD-9. The effects of the strain on the growth and acetochlor accumulation of maize seedlings were also analyzed in laboratory-scale pot experiments. Inoculation of the strain in soil could significantly improve growth (> 9.4%) and phosphorus uptake (> 14.8%) and decrease the accumulation (> 70%) and toxic effects of acetochlor on seedlings. Taking the results together, strain ACD-9 may be useful in the degradation of acetochlor in soil and promotion of the growth and phosphorus uptake of maize.

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