The Study Of A Efficient Malathion-Degrading Bacterium On Screening And Characteristic Research

Nowadays,organophosphorus pesticide residues in food are common and serious pollution in China,especially pollution of some highly toxic residual organophosphorus pesticides in food can not be ignored.In this dissertation,taking organophosphorus pesticide malathion as a model pollutant,isolating four strains of malathion which has a good ability to degrade from Shenyang ecology park long-term experiments and spray pesticide malathion soil by the way of gradual domestication,and get a better performance-degrading bacteria M5 after rescreening,which degradation rate to malathion of 52%.Studying the growth curves of malathion degraded bacteria M5,and growth characteristics at different factors,such as pH,temperature,carbon and nitrogen and concentration of malathion.Experiments show that the degraded bacteria M5 in 3-4d reached stationary phase,from the 6th day start to decline phase.Also the experiments show the best time for the degraded malathion is the 4th day which can reach the maximum degraded rate,the degradation rate reached 52%after 6th;the optimal culture temperature for degraded bacteria M5 is 30?,the optimal culture pH value for degraded bacteria M5 is 7.0,when the concentration of malathion of 1000mg/L,which has the maximum degradation;has the most vigorous growth with carbon source.Studying the influence of death rate at different ultraviolet light exposure time,the mass fraction of sodium bicarbonate solution and the volume fraction of soil leachate,after the best mutation conditions were determined,composite mutagenesis the three methods,put the medium at a position 30cm 20W UV light irradiation 10s,the mass fraction of 0.6%sodium bicarbonate solution 120r/min constant vibration 30min,finally the volume fraction of 60%soil leachate 30 ? constant temperature for 48h.Screening a good effect degraded strains of pesticide malathion by gas chromatography,the degradation rate has increased significantly after composite mutation,19.26%higher than before,which the maximum degradation rate of 69.26%after 30d.Identified strain M5 'as Pseudomonas stutzeri by morphological,physiological and biochemical characteristics and molecular identification.Evalution on the safety of use,according to the national standard of microbial safety regulation,the Pseudomonas stutzeri as fourth category for the highest degree in biological safety,use safety.Using the simulation test of single factor farm to approach,determine the effect of different factors on the ability of bacteria degraded,such as pH value,organic manure fertilizer,agents and the amount of soil moisture,the results shows that the best environment factors of degradation as follows:pH value of 5.0,organic fertilizer about 5g/kg,agents dosage about 50mL/kg,soil water content about 70%.