1株DEHP高效降解菌的分离鉴定与降解特性OA

[Objective]An efficient DEHP[di(2-ethylhexyl)phthalate]degrading bacterium was isolated from farmland soil in cold region to provide the scientific basis for establishing an effective remediation technology to control DEHP-contaminated soil in cold regions.[Method]The inorganic salt medium(MSM)with DEHP as the single carbon source was used to isolate strains with DEHP degradation ability from farmland soil in Harbin.The isolated degrading strains were identified by morphological and 16 sDNA analysis.The growth conditions of the isolated degrading strains were optimized by single-factor experiments(A,pH;B,inoculation volume;C,temperature;D,shaker speed).The optimal growth conditions for the isolated degrading strains were screened by response surface analysis according to the results from single-factor experiments.[Result]One strain with a DEHP degrading capacity screened from the soil was named as strain Y1.The 16S rDNA sequence homology between strain Y1 and Pseudomonas monteilii strain JM10 was 99.65%.Strain Y1 was classified into Pseudomonas genus and named as Pseudomonas sp.Y1 according to its morphological characteristics of bacterial growth.The quadratic polynomial regression equation of strain Y1 for DEHP degrading rate was:Degradation rate=96.65+2.53A+1.93B+1.92C-2.15D+0.14AB+0.05AC-1.35AD+1.54BC-0.44BD-0.855CD-11.95A2-2.11B2-16.77C2-8.29D2.The pH,shaker speed,temperature,inoculation volume,quadratic term of pH,quadratic term of shaker speed and quadratic term of temperature all influenced the degradation rate of DEHP very significantly,and the quadratic term of inoculation volume influenced the degradation rate of DEHP significantly.The effect of four factors on degradation rate of DEHP was pH＞shaker speed＞inoculation amount＞temperature.The response surface analysis showed that the DEHP degrading rate of strain Y1 was relatively low in an environment with pH range of 6.0-6.5.The DEHP degrading rate of strain Y1 gradually increased with increase of pH.The acidic environment had a stronger impact on DEHP degradation capacity of Y1,and the degradation efficiency of strain Y1 showed a more variation.When the culture environment became alkaline,the impact on degradation rate was lower than that of an acidic environment.Strain Y1 had a strong DEHP degrading performance at 20-30℃.The optimal degradation conditions included pH 7.0,3.50%inoculation volume,175 r/min shaker speed,25℃and 3 d culture.The DEHP degrading rate of strain Y1 cultured on MSM under the optimal degradation conditions reached 96.63%.[Conclusion]Pseudomonas sp.Y1 is an efficient DEHP degrading bacterium.Strain Y1 with 96.63%DEHP degradation rate under the optimal degradation conditions is of a good application prospect in the cold climatic environment.