Isolation Of The Quinclorac-degraded Microbes And Studies On The Degradation Of Quinclorac

Quinclorac belonged to qμinoline carboxylic acid is a weedicide,which can result in phytotoxicity to next crops because of a longer persistence in the field.In this study ,we isolate and screen a strain from soil contaiminated by long term exposed to weedicide.The isolated strain can make use of the quinclorac as unique Carbon and Nitrogen source to grow.We name the strain as fhb in short.Firstly,we sequence and align 16s rDNA of this strain,showing that the similarity of fhb’16s rDNA with the Pseudomonas aeruginosa is 100%.Combining with the main physiological and biochemical characteristics,we identify fhb as Pseudomonas aeruginosa.The main physiological and biochemical characteristics inclμde:fhb is a bacillμs and G- negative bacterium;the results in the test of acid prodμction of glμcose oxidase,oxidase,Catalase test,Nitrate redμction test and Gelatin liqμefaction test are all positive;the results in the test of Starch hydrolysis, MR test,VP and indole test are all negative.Secondly,we study fhb’ability of degradation to quinclorac.The results indicate that when fhbuse the quinclorac as unique Carbon and Nitrogen source to grow, ethe optimal temperaure and pH of degradation to quinclorac are 35℃and 6-8.The rate of degradation to 500mg/L quinclorac is about 90% during 36h.It also show that it do not increase the ability of degradation when adding Glucose as Carbon source.In the final,we study the differences of expessed proteins of fhb between in the condition of no quinclorac and quinclorac stress by SDS-PAGE.We find that catechol 1,2-dioxygenase play an important role in the process of degradation to quinclorac by determining the varity of activity of catechol 1,2-dioxygenase in different culture conditions.RNA of fhb in different culture condition are reversely transcripted to cDNA,then amplify by RT-PCR.The result shows that catechol 1,2-dioxygenase in fhb is induced by quinclorac at the level of RNA and play an important role in the process of degradation to quinclorac.