A bacterium(designated strain Y1) degrading acetanilide herbicide mefenacet was isolated from aerobic sludge. Based on the analyses of partial 16S rRNA gene, cellular fatty acid and BIOLOG-GN, and general physiologica...A bacterium(designated strain Y1) degrading acetanilide herbicide mefenacet was isolated from aerobic sludge. Based on the analyses of partial 16S rRNA gene, cellular fatty acid and BIOLOG-GN, and general physiological and biochemical characteristics, strain Y1 was identified as Sphingobacterium multivolum. Strain Y1 was able to degrade mefenacet used as sources of carbon and energy. Degradation of mefenacet was accompanied by producing the metabolites N-methylaniline and an unidentified compound with molecular weight 205, indicating a metabolic pathway of mefenacet initiated by hydrolysis of amido bond.展开更多
The effect of acetanilide herbicide mefenacet on soil microbial communities was studied using paddy soil samples with different short-term treatments. The culturable bacteria （plate counts）, dehydrogenase activity a...The effect of acetanilide herbicide mefenacet on soil microbial communities was studied using paddy soil samples with different short-term treatments. The culturable bacteria （plate counts）, dehydrogenase activity and changes in community 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 multivorum Y1, a bacterium efficiently degrading the mefenacet, only induced the increasing colony-forming unit （CFU） of bacteria but little effect on dehydrogenase activity during the whole experiment. The degree of similarity between the 16S rDNA profiles of the communities was quantified by numerically analyzing the DGGE band patterns. Similarity dendrograms showed that the microbial community structures of the mefenacet-treated and non-treated soils were not significantly different. 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 attempt to apply the S. multivorum Y1 for remediation of the mefenacet-polluted environments.展开更多
Sorption and cosorption of the nonionic herbicide mefenacet and two typical metals （copper and silver） on black soil and its components （kaolinite and humic acid） were investigated. It was found that because of th...Sorption and cosorption of the nonionic herbicide mefenacet and two typical metals （copper and silver） on black soil and its components （kaolinite and humic acid） were investigated. It was found that because of their different valences and properties, Cu2＋and Ag＋ presented different effects on the sorption of mefenacet. Due to the competition of Cu2＋, along with the shells of dense water formed by its surface complexation, for sorption surface area with mefenacet, the addition of Cu2＋ decreased the sorption amount of mefenacet on soil and its components, especially on humic acid. However, the addition of Ag＋ significantly enhanced the sorption of mefenacet, which was attributed to the softness of the cation that weakened the hydrophilicity of the local region around Ag＋-complexed functionalities, and thus mitigated the competitive sorption of water. In addition, the sorption of mefenacet on soil with or without the two metals was generally decreased with increasing pH, which was caused by the hydrolysis of carbonyl and carboxyl groups on the surface of the sorbents, π-π interaction between mefenacet and the soil organic matter, and so on. On the other hand, the presence of mefenacet seemed to have little effect on the sorption of Cu2＋ and Ag＋, indicating that Cu2＋ and Ag＋ might be sorbed strongly on the tested sorbents and the mefenacet added was too low in concentration to affect the sorption of the metals.展开更多
文摘A bacterium(designated strain Y1) degrading acetanilide herbicide mefenacet was isolated from aerobic sludge. Based on the analyses of partial 16S rRNA gene, cellular fatty acid and BIOLOG-GN, and general physiological and biochemical characteristics, strain Y1 was identified as Sphingobacterium multivolum. Strain Y1 was able to degrade mefenacet used as sources of carbon and energy. Degradation of mefenacet was accompanied by producing the metabolites N-methylaniline and an unidentified compound with molecular weight 205, indicating a metabolic pathway of mefenacet initiated by hydrolysis of amido bond.
文摘The effect of acetanilide herbicide mefenacet on soil microbial communities was studied using paddy soil samples with different short-term treatments. The culturable bacteria （plate counts）, dehydrogenase activity and changes in community 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 multivorum Y1, a bacterium efficiently degrading the mefenacet, only induced the increasing colony-forming unit （CFU） of bacteria but little effect on dehydrogenase activity during the whole experiment. The degree of similarity between the 16S rDNA profiles of the communities was quantified by numerically analyzing the DGGE band patterns. Similarity dendrograms showed that the microbial community structures of the mefenacet-treated and non-treated soils were not significantly different. 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 attempt to apply the S. multivorum Y1 for remediation of the mefenacet-polluted environments.
基金supported by the Natural Science Foundation of Jiangsu Province (No. BK2009254)
文摘Sorption and cosorption of the nonionic herbicide mefenacet and two typical metals （copper and silver） on black soil and its components （kaolinite and humic acid） were investigated. It was found that because of their different valences and properties, Cu2＋and Ag＋ presented different effects on the sorption of mefenacet. Due to the competition of Cu2＋, along with the shells of dense water formed by its surface complexation, for sorption surface area with mefenacet, the addition of Cu2＋ decreased the sorption amount of mefenacet on soil and its components, especially on humic acid. However, the addition of Ag＋ significantly enhanced the sorption of mefenacet, which was attributed to the softness of the cation that weakened the hydrophilicity of the local region around Ag＋-complexed functionalities, and thus mitigated the competitive sorption of water. In addition, the sorption of mefenacet on soil with or without the two metals was generally decreased with increasing pH, which was caused by the hydrolysis of carbonyl and carboxyl groups on the surface of the sorbents, π-π interaction between mefenacet and the soil organic matter, and so on. On the other hand, the presence of mefenacet seemed to have little effect on the sorption of Cu2＋ and Ag＋, indicating that Cu2＋ and Ag＋ might be sorbed strongly on the tested sorbents and the mefenacet added was too low in concentration to affect the sorption of the metals.
