Screening Of Acetochlor Degrading Bacteria In Soil And Prime Influencing Factors Study

Acetochlor are used for preventing weed in crop such as corn,soja,earthnut,cotton,potapo in north widely.It is the one of three most herbicides used.Although it provides help for agriculture, negative effect should not be ignored.Besides direct toxicity,it is with the characteristict of residue and is difficult for ivolatilization and photolysis.The raw oil of it is lipophilic soil molecule. Water-solubility is infinitesimal.It is latent threaten to entironment and human hugely.Our experiment adopts the way of enrichment cultivation in soil,isolates the degrading microbe for Acetochlor.then,determines the effect of degrading microbe of Acetochlor by gas chromatography one by one.relegates to authority organization for identifying the best degrading bacteria by molecular biology.Farther,we pilot study the prime influencing factors.Providing some reference with managing residue of acetochlor by microbe henceforth.The prime results is as follows:1.Cultivation and Isolates of Degrading MicrobeWe select the soil in the farmland of Weihai in Shandong province,Taizhou in Jiangshu province,Chongqing and silt of sewage pool in pesticide factory manufacturing acetochlor,confect inorganic salt substrate by original pesticide of Acetochlor as the only C source and N source of bacteria and epiphyte in soil.We adopt the way of enrichment cultivation,get 14 kinds of degrading bacteria of acetochlor by isolateing and sublimating time and time again.Concretely,we get 5 kinds of degrading bacteria in soil of Chongqing,three ones absorbing C source,two ones absorbing N source;get 5 kinds of degrading bacteria in soil of Shandong,two ones absorbing C source,three ones absorbing N source;get 4 kinds of degrading bacteria in soil of Shandong,two ones absorbing C source,two ones absorbing N source.No one can be isolated in soil of sewage pool in pesticide factory.2.Determining of the degrading effectDetermining the effect of 14 kinds of degrading Bacteria by gas chromatography.The Degradation rate are Yu C1:20.06%,Yu C2:0.39%,Yu C3:1.07%,Yu N1:10.48%,Yu N2: 12.83%,Lu C1:16.33%,Lu C2:29.20%,Lu N1:24.38%,Lu N2:9.84%,Lu N3:16.23%, Su C1:18.63%,Su C2:2.48%,Su N14 6.08%,SU N2:6.51%.the best one is Lu C2.3.identifying of the most effect degrading BacteriaWe relegate LuC2 to southwest Bacteria station of China center of Industrial Culture Collection,identify the bacteria by molecular biology.The beactria is Stenotrophomonas maltophilia.4.Prime Influencing Factors of degradation effect StudyMake sure the Prime Influencing Factors are:time of degradation,capacity of bacteria,rate of soil containing water,temperature and concentration of Acetochlor.The result of study show:Effect of time of degradation:in the beginning of 15 day,the degradation effect is positive correlative with time of degradation basically.After 15 day,the degradation rate keeps invariable basically,will not increase.Effect of capacity of bacteria:with the capacity of bacteria increasing,the degradation rate will also increase gradually,the correlativity is very good.Effect of rate of soil containing water:before the rate of soil containing water reach 100%,the degradation effect is positive correlative with rate of soil containing water basically.Beyond 100%, the degradation rate keeps invariable basically,will increase slowly.Effect of temperature:wholly,there is a parabola relation between degradation effect and temperature.When temperature is 30℃,the degradation effect is the highest.Effect of concentration of acetochlor:For degradation effect,there is always some effect from concentration of acetochlor,but it is tiny.