Isolation, Identification And Degradation Characteristics Of Mcpa Degradating-strains

2-methyl-4-chlorophenoxy acetic acid (short for MCPA) is widely used in tobacco and rice fields in China. However, due to its high application quantity, the problems of environmental pollution and food safety have attracted wide attentions. Microbial bioremediation technique has been showing extensive prospects for use in soil contaminated with herbicide. It is important to isolate high efficient MCPA-degradating strains and use these strains to clean up the contaminated environments..A MCPA-degrading bacteria SE08was isolated from the polluted tobacco field soil, which have been collected from Chenzhou city, Hunan province. Morphological observation, physiological biochemical tests,16S rRNA gene phylogenetic analysis of strains SE08were studied. For bioreediation of rice culture environment, degradation effect of MCPA pollutants was studied in the simulated condition with functional bacteria. The main results are as follows:1.4MCPA-degrading strains were isolated from rice field soil,which could only grow and degrade MCPA in LB medium. Among these strains, a bacterial strain named SE08capable of utilizing MCPA as the sole carbon sources for growth. Based on the morphology, physiological biochemical characteristics, and16S rDNA sequence analysis, strain SE08is a non-spore-forming, gram-negative, rod-shaped bacterium. It was identified as Enterobacter sp, and registration id in GenBank was HM461219.2.Strain SE08could effectively degrade MCPA ranging of150-3000mg/L. Degradation characteristics tests showed that MCPA-degrading rate of SE08was the highest as40.83%in the mineral salt medium with500mg/L of MCPA as the sole source of carbon, after being incubated at35℃, pH6.0and200r/min for24h.3. Effects of Enterobacter sp. with different adding dose on remediation of MCPA polluted rice soil were studied in simulated conditions. when SE08was inoculated into rice soil at the concentration of4%per gram dry soil and concentration of MCPA is100μg/kg, emergence rate of rice was enhanced29%,while height inhibition rate was reduced to19.8%, relative to control group.