一株DDT降解菌的鉴定及其生物学特性

Identification and biological characterization of a DDT degrading bacterium strain

利用DDT为唯一碳源筛选、纯化得到DDT降解菌株DT1,通过形态特征、生理生化特性及系统发育分析鉴定为假单胞菌属细菌(Pseudomonas sp.)。通过单因子试验及差异显著性分析得到菌株DT1的最佳生长条件为37℃、初始p H值8.0、DDT初始质量浓度20mg/L、最适Na Cl质量浓度1 mg/L。通过正交试验优化菌株DT1的降解能力,最优方案为温度37℃、p H值9.0、DDT初始质量浓度30 mg/L,可将DDT降解率提高到60.85%。影响其降解能力的环境因素从主到次依次为温度、p H值、DDT初始质量浓度。

The paper is aimed at introducing our research results for isolating,identifying and characterizing a DDT-degrading bacterial strain known as DT1 from the DDT contaminated site,which has been done via the analysis of its morphological and physio-biochemical features. The strain we have isolated is known as Pseudomonas sp. to be adopted for analyzing its morphological,physiological and biochemical features,with a 16 S rD NA sequence and the phylogenetic tree. What is more,the strain we have cultured can be found growing perfectly by taking DDT as its only carbon source,with its degrading efficiency for DDT being determined by the gas chromatography. In addition,the growth rate and DDT degradation rate of the said strain DT1 have both been made to reach the maximum limit for a period of 96 h. The optimal growing conditions of the strain have all been examined with the single factor test,whereas the maximum degradation capability of DDT has been determined by way of doing an orthogonal experiment. As a result,we have confirmed and determined that the optimal conditions for the cell growth should be stated as follows： the temperature needed： 37 ℃; the initial pH value：8. 0; the medium salinity： 1 mg / L,in addition to the DDT concentration,which should be chosen as 20 mg / L. Furthermore,it has also been found that on the condition when the initial concentration of DDT is 50 mg / L at the temperature of 37 ℃ with the pH value being9. 0,after the dark culture lasting for 96 h,it would be possible to promote the degradation rate of DDT with the said strain to a rate as high as 60. 85%. The primary and secondary order of the environmental factors that may affect the degradation ability of DT1 should be stated in the following descending manner： temperature pH DDT concentration. The above order proves that strain DT1 has high capability for degrading DDT,which can thus be expected to enjoy an optimistic application prospect in bioremediation of the DDT contaminated soil.