Degradation Of Quinclorac By Combined Bacteria

Quinclorac is growth hormone herbicide which can control weed of rice fields.But the long-term use of quinclorac can lead to a large number of Quinclorac residues in the soil and have a great impact on yield and quality of plants.In this study,a strain of bacteria in the pesticide plant sludge was isolated,named D,which can degrade quinclorac.And when it mixed with Pseudomonas F1,we found that the degration rate of the mixture increased significantly.Firstly,the conditions of using HPLC waters 2695 to detecte the quinclorac was analyzed,and the results were as fellows: the mobile phase was 60% methanol and 40% ice acetic acid(1%),and the flow rate was 1 m L/min;the detection wavelength was 240 nm;sun fire C18 column;35 ℃;the peak time was about 7 min without impurity peak.The accuracy of this method was 98.54%,and the range of the recovery rate was 86.28%-100.75% with RSD 1.06%-1.06%.Secondly,we isolated a strain of bacteria in the pesticide plant sludge,named D,which takes the quinclorac as the sole carbon source.The results of 16 S r DNA sequencing showed that the similarity of 16 S r DNA sequence with strain D and Klebsiella sp.was 100%.With the main physiological and biochemical characteristics,we defined strain D as Klebsiella.At the same time,the research results of the Klebsiella D to quinclorac was that when temperature of quinclorac degradation was 35℃and pH was 8,the rate of 100mg/L quinclorac degradation by Klebsiella D reached maximum,about 41.9%.Under the condition of adding glucose,the degradation rate of quinclorac did not significantly change.Thirdly,study of the degradation of quinclorac by Klebsiella D and Pseudomonas F1 showed that compared with the single strain,the mixed of strain D and F1 could increase the degradation rate of quinclorac by 5%.With inoculation quantity increasing,the degradation rate increased,the degradation rate was 48.3%.The optimum mixing ratio of strain D and F1 was 4:1.Under this optimum mixing ratio,the degradation rate of quinclorac in sterilized soil was 33.2% at 20 d,while in non sterilized soil,the degradation rate was 46.9%.Finally,we studied the differently expressed proteins in Klebsiella D in the condition of nonquinclorac and quinclorac stress by SDS-PAGE.Under the stress of quinclorac,the proteins of strain D changed in cell were both internal and external.Intracellular changes were mainly in the 29 KDa and 60 KDa,and the change of extracellular was mainly in 31 KDa.All these proteins might be associated with the degradation of quinclorac.