Monitoring impact of mefenacet treatment on soil microbial communities by PCR-DGGE fingerprinting and conventional testing procedures

The effect of acetanilide herbicide mefenacet on soil microbial commun ities was studied using paddy soil samples with different short-term treatments. The culturable bacteria(plate counts), dehydrogenase activity and changes in co mmunity structure (denaturing gradient gel electrophoresis(DGGE) analysis) were used for biological community assessments. Mefenacet was a significant stimulus to cultural aerobic bacteria and dehydrogenase activity while Sphingobacterium m ultivorum Y1, a bacterium efficiently degrading the mefenacet, only induced the increasing colony-forming unit(CFU) of bacteria but little effect on dehydrogena se activity during the whole experiment. The degree of similarity between the 16 S rDNA profiles of the communities was quantified by numerically analyzing the D GGE band patterns. Similarity dendrograms showed that the microbial community st ructures of the mefenacet-treated and non-treated soils were not significantly d ifferent. But supplement of S. multivorum Y1 could increase the diversity of the microbial community in the mefenacet-polluted paddy soil. This work is a new at tempt to apply the S. multivorum Y1 for remediation of the mefenacet-polluted en vironments.