[Isolation, identification and soil remediation of fomesafen-degrading strain FB8]

In order to find new strains to degrade fomesafen in contaminated soil, we isolated and identified a high-efficiency degrading bacterium from polluted soil. The degrading characteristics and remediation ability of the strain were also studied.

Characteristics of morphological, physiological, biochemical and 16S rRNA sequence were applied to identify the strain. The optimum growth conditions were obtained by studying the effect of environmental factors such as fomesafen concentration, primary pH and temperature on the strain. The strain's remediation ability to fomesafen-polluted soil was verified by sensitive crop and target weeds bioassay in pot soil.

A high-efficiency degrading strain FB8 that used fomesafen as sole carbon source was isolated from soybean field suffering fomesafen in Heilongjiang province. It was initially identified as a member of the genus Pseudomonas. The strain could degrade 86.75% of 500 mg/L fomesafen within 96 h. Its optimal growth conditions were determined as follows: 500 mg/L fomesafen, primary pH between 6.0 and 8.0, and at 35 to 37 degrees C. The strain could remedy the sensitive crop maize and sorghum biomass after treating for 30 d for soil contaminated with 5 mg/kg of fomesafen.

A fomesafen-degrading strain FB8 was selected from fomesafen-contaminated soil in Heilongjiang Province. The strain was closely related to Pseudomonas mendocina. The strain was a suitable candidate for bioremediation of fomesafen-contaminated soil.