| China is an agricultural country.The use of large number of organophosphorus pesticide effectively controlled weeds and pests in crop growth,but also cause serious environmental pollution,pesticide pollution questions are very prominent.Therefore,we must decontaminate and restore the water and soil polluted by organophosphorus pesticide timely.It is of great realistic significance to block pollutants from entering the food chain, to prevent harm to human health,and promote the protection of land and water resources and the sustainable development of agriculture.In this paper,we isolated a bacteria strain of C-1 that could degrade methamidophos pesticides with high efficiency from soil polluted by methamidophos for many years.The bacteria in the solid medium are large,white,round,smooth.C-1 is a gram-negative bacterium,spherical.Cultivating it shaking(180 r·min-1) at 35℃,C-1 entered the logarithmic growth phase after being cultivated 6 hours,entered stable phase 36 hours later,and began to decline 42 hours later.They grew well at 25℃～40℃and pH 6～10. The optimal temperature and pH for cell growth were 35℃and pH 7.Its tolerant concentration to methamidophos can add up to 5 000 mg·L-1,while the most suitable concentration to methamidophos is 2000 mg·L-1.It can make use of methamidophos as nitrogen source,but can't make use of methamidophos as carbon and phosphorus source. C-1 used in the soil helped to improve the activity of the whole soil microorganism group.in different carbon liquid medium,C-1 using maltose as carbon source have the highest rate of degradation of methamidophos,cultured for 72 hours,the degradation rate was 80.2%,Cultivated under the optimum conditions for 24 hours,the degradation rate was 21.2%,36 hours later,the degradation rate increased to 63.7%,72 hours later,the rate of degradation reached 80.9%.In different nitrogen liquid medium for 3 days,the degradation rate were basically the same,the degradation rate were about 80%.With other nitrogen sources existing,C-1 use methamidophos as nitrogen source for priority,fertilizer in the soil will not affect the effects to the degradation of methamidophos of C-1.In the soil and inoculation of 5 g·kg-1,its maximum degradation rate of methamidophos was 96.3%.Through the research of the bioremediation effect of the soil with different concentrations of methamidophos,when the concentration of methamidophos of the soil between 2 mg·kg-1 and 300 mg·kg-1,methamidophos can be restored to below 0.5 mg·kg-1.It can reach the concentration of the national standards,and it is notable of the effect of bioremediation.Through the research of the bioremediation effect of methamidophos in different moisture content of the soil,the more moisture content in the soil,the better the bioremediation effect of the methamidophos will be.From the changes of the content of inorganic phosphorus we measured in liquid medium,we can see inorganic phosphorus come out in the process.Analyzing the chromatograms in the test of degradation and the blank,there was no other organic phosphorus produced.Methamidophos can be completely degraded into inorganic phosphorus by C-1.Its degradation pathway may be:firstly C-1 interrupted methamidophos' P-N bond,and then made use of methamidophos as nitrogen to grow.When C-1 grew to a certain extent,they produced methamidophos degrading enzyme,then interrupted P-O bond and P-S key,finally completely degradated methamidophos into inorganic phosphorus,Using C-1 to degrade methamidophos can achieve the purpose of bioremediation.
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