Screening, Purifying And Studying On The Microorganisms For Degrading The Ethametsulfuron-methyl

The residues of ethametsulfuron-methyl in soil have been reported to cause damage to succeeding rice and other crops.It need to develop a method for the detoxification of ethametsulfuron-methyl in soil and elimination of its harmfμl effect on crops.In the study, one ethametsulfuron-degrading strain named B14 was isolated by biological concentration and domestication.Its growth characteristic,degrading ability were also investigated.The brief results are follows.1.67 strains were isolated by enrichment culture and domestication from soil samples in Hunan agriculture university experimentation farm.The fungal strain B14 was select for the best capable of utilizing ethametsulfuron as sole carbon source by HPLC detecting. Based on the results of biomorphic features,type culture medium,and phylogenetic similarity of 18S rRNA gene sequences,the isolated strain was designated as P.expansum Link.The 18S rRNA partial sequences were deposited into the GenBank under accession No.EU128638.1.2.Through the biological character culturing on different condition,B14 favors PDA culture medium.The myceliμm of B14 grew best under the temperature of 25℃and the pH of 6.0.The conidium germinated best with the temperature of 20℃,the pH of 5.0 and high moisture.At the same time,the results showed The strain B14 growth liked darkness better.3.By B14 culture based on utilizing ethametsulfuron as sole carbon source in inorganic salt solution,as a result,B14 adapt to degrade ethametsulfuron in the original concentration of 20mg/L,the inculation of 8%,the pH of 6.5 and the temperature of 28℃circμmstances.In the fittest conditon,the ethametsulfuron degrading curve described by first order kinetics reaction equation linear regression,Ethametsulfuron degradation kinetics follow the first order kinetics:C_t=23.94·e^-0.0221t,Its square of correlation coefficient was 0.9865.92.33%of ethametsulfuron was removed after 25d In fittest culture condition.The soluble enzymes from cell-free extracts of strain B14 can degrade 87.32%of ethametsulfuron in 72h.This shows that the soluble enzymes were the primary removal enzymes.91.90%and 89.02 of the initially added 20 mg/L ethametsulfuron was removed after 25d for natural dried fresh soil and sterilized soil inoculated with strain B14.In contrast,Only 14.81%and 8.05%was removed in uninoculated natural dried fresh soil.Therefore,ethametsulfuron removal improved significantly in soils inoculated with strain B14.