| Bensulfuron-methyl is for controlling weeds in planting rice fields,such as Monochoria vaginalis,Potamogeton distinctus,and sedge family weeds such as Sagittaria pygmaea and Cyperaceae,etc.,bensulufuron-methyl is considered as a kind of high efficiency,wild used,low toxic and low-dosage herbicide,which is widely used in rice weed controlling and one of the primary herbicides.Bensulfuron-methyl is of high selectivity and biological activity;its sensitivity varies from crops to crops;therefore,the chemicalinjuries are easy to be taken place by residual Bensulfuron-methyl on sensitive crops.The way of enrichment cultivation in soil,isolates the degrading microbe for Bensulfuron-methyl is adopted in this study.Then,the effects of degrading microbe of Bensulfuron-methyl were determined by HPLC one by one.The best degrading bacteria was relegated to interrelated organizations for morphological and molecular-biological identifying; the methods of mutagenic treatment to the target bacteria were tentatively studied either.So these series of researches have provided references to the further works on environal-microbe applying on Bensulfuron-methyl,the main results are as follows:1 domesticating and separating of endurable bacterium to Bensulfuron-methylThirty-seven strains of Bensulfuron-methyl(700 mg/L) endurable bacterium were abtained, after being treated in high chroma of Bensulfuron-methyl constantly for 7 months,among which 21 strains were screening from polluted soil;the others were from field soil.2 measuring of degradative resultsRegression equation Y=5.06-7X-0.0561(R2=0.9997) was abtained,which showed that the Responding Peak area of HPLC and each chroma of Bensulfuron-methyl were related in linar regressionThe degradative results of 37 strains of Bensulfuron-methyl endurable bacterium degradated Bensulfuron-methyl were differed from each other.Among those,there was only one strain named Co6,whose degrading rate of Bensulfuron-methyl was 32.4%.By the way,Co6 was screening from polluted soil in Jianyang,Sichuan.3 Identification of Co6 and researching about its optimal growthing conditionAfter identifying in related department,Co6 was definited as Bacteria,Firmicutes,Bacilli, Bacillales,Paenibacillaceae,Brevibacillus.To determine the optimal growthing conditions of Co6,series of reserches were carried out.The results indicated that Co6 grew the best under 500 mg/L Bensulfuron-methyl with pH 7.0,29℃.4 Mutagenic domestication resultsTow kinds of mutagenic bacteria,uv40-60 and m3-60,were obtained after using ultraviolet and chemical mutagenic methods.In details,Co6 was treated under 254 nm 40 W ultraviolet irradiating for 60 s and under adding 1 mL MNNG(0.01 g/L) with pH 7.5 for 60 min, respectively.Finally,the degredating rates of these two kinds of mutagenic bacteria were 38.9% and 35.2%.In general,one kind of degradative bacteria to Bensulfuron-methyl,which was named as Co6,was isolated through this study,and its degradative ability was enhanced to a certain degree by using ultraviolet and chemical mutagenic methods at a time.This result indicated that it's feasible to heighten the degradative ability of bacteria to Bensulfuron-methyl by adopting mutagenic method.Furthermore,bacteria with higher degradative ability might be obtained,if it was put under the mutagenic conditions more than once,and with the condition of Bensulfuron-methyl whose chroma was increasing gradually.The current study has not only provided evidence of useful methods of screeing and breeding degradative bacteria to Bensulfuron-methyl,but also will contribute to selecting other kinds of degradative bacteria to different chemicals. |
PDF Full Text Request