Isolation And Characteristics Of A Methamidophos-degradation Bacteria

Methamidophos (MAP) and other organophosphate pesticides are highly toxic and widely used for insects control in many countries. However, these pesticides also cause serious problems to the environment and food safety. How to solve the problem has become a public concern.It has been known that MAP can be mineralized by some microorganisms.The strain of MAP -degrading B-4 was isolated from the polluted soil around Shijiazhuang Pesticides Factory, China. Study on its physiologic and biochemical analysis proved that it is a Bacillus licheniformis. MAP can be used by the strain as sole carbon source ,nitrogen source and energy source. And it could degrade parathion and dichlorvos effectively as well. Its optimal pH is 7.0 and optimal temperature is 28 "C. After 72 hours of inoculation in a inorganic salt medium amended with 200mg/L MAP and shaking (150rpm/min) at 28'C, 72.5% MAP was degraded.The growth and degradation curve showed that the two curve trends were similar. The degradation of MAP was attributed to the enzyme produced in the growth period.Degrading enzymes (or enzyme system ) were induced by pesticides. Its biodegrability was affected by additional carbon source contained in the medium.The degradation rate of MAP was 79.95% in 5 days when the water content in soils was 150%(paddy soil) in laboratory test. The test also showed that degradation rate in paddy soil was higher than that in upland soil.