The Isolation Of Pendimethalin Degrading Microbe And The Research Of Degrading Character

Now environmental biotechnology has become a popular field of environment science and biology. The biological waste treatment is the most important means of pollution control. Pesticides are the poisonous pollutants more than others and have more influences than other pollutants. So the study of pesticides degradation ought to be enhanced. Pesticide degradation in environment mainly is biodegradation by microbe. In this research paper what are mainly studied was the biodegradation of pendimethalin. Some strains of microbe which could effectively degrade pendimethalin in culture were isolated. Properties of pendimethalin biodegradation were studied and biological properties of strain HB-7 were researched. These researches can offer more extract and valid bases and evidences for the biodegradation of pesticides and bioremediation of pesticides pollution. The results could be summarized as followings:1. In this paper the extraction and analysis methods were studied. The study of extraction rate of different methods in culture solution demonstrated that pendimethalin was strongly sorbed by microorganism especially by fungi. The pendimethalin was absorbed by microbe in short time and was not degradated. So the high extraction rate and simple operation should both considered in choosing the extraction methods. The pendimethalin was detected by GC-14C gas chromatography with 63Ni-ECD. The recovery rates in fungi culture of l.O.lO.O.lOO.Omg-L'1 was 96.67?.98%, 97.62?1.83%, 97.43+2.17% respectively and 99.88 + 0.55%, 98.70+0.41%, 98.13 + 0.42% in bacterial culture. The results could meet the requirements for analysis of pendimethalin residue.2. Fungi degrading pendimethalin were isolated by enrichment from soil and sludge. 23 fungi were got. 16 fungi could degrade more than 50% pendimethalin in 5 days in culture fluid and 10 fungi could degrade more than 60%. Three fungi YF-102, YF-212, YF-216 were considered as efficiently degrading strains identified as Aspergillus terreus, Monilochaetes and Aspergillus fivnigatus.3. The pendimethalin degrading bacteria were isolated by two methods. 12 bacteria strains were got by selective enrichment from soil and active sludge with cane sugar as carbon source in addition to pendimethalin. But no efficiently degrading strain was found.18 bacteria strains were got by selective enrichment from soil and active sludge with pendimethalin as sole carbon source. 5 strains could degrade more than 60% pendimethalin in 3 days in culture fluid and 3 strains HB-1, HB-7, WB-1 could degrade more than 80% considered as efficiently degrading strains. These 3 strains were preliminarily identified as Pseudomonas^ Bacillus and Mirococcus luteus.4. The effects of culture conditions on pendimethalin by fungi were studied.The efficiency of degradation was affected by culture conditions such as pH, temperature, the concentration of cane sugar and pendimethanlin. The optimal conditions of fungi and bacteria culture were proposed.5. The properties of biodegradation of bacteria were studied. The culture conditions such as pH , temperature, the concentration of cane sugar and pendimethanlin had effects on the degradation and bacterial growth. The optimal conditions were pH7.0, 30C, 0.1-0.2% cane sugar and no more than lOOmg-L"1 pendimethanlin.6.Microbial physiological tolerance of pendimethalin had something to do with the degrading capacity. But they had no directly relation and not all of the tolerant species were efficiently degrading strains.T.Many models could be used for describing pesticide -substrate bioavailability and rates of biodegradation in environment. Among these models C=C0e~Kt was used extensively. The results showed that C=Coe"Kt could be used for describing biodegradation of pendimethalin by bacteria.8. The study of environmental safety of strain HB-7 showed that it could not contaminate environment doing no harm to tobacco and fat. So the strain could be used in bioremediation of soils contaminated with pesticides and disposal of sewage.9.The study of in...