邻苯二甲酸二甲酯(DMP)降解菌的分离鉴定及降解特性

采用梯度压力驯化法从河流沉积物中筛选到一株能够以邻苯二甲酸二甲酯(Dimethyl Phthalate,DMP)作为碳源和能源生长的菌株,命名为THF-2,对其进行16S r DNA扩增、T/A克隆后测序,菌株THF-2被鉴定为恶臭假单胞菌(Pseudomonas putida)。研究了温度、初始p H值和表面活性剂对菌株THF-2降解DMP的效果,测定了邻苯二甲酸酯(PAEs)对菌株THF-2生长的影响,进而分析了菌株对不同质量浓度DMP的降解效果。结果表明,菌株在15~20℃对DMP具有良好的降解效果,最适温度为20℃;在p H=4~8范围,随p H值升高,DMP降解率增大,最佳p H值条件为8.0。在最适条件下,经过72h培养,菌株THF-2对质量浓度500 mg/L的DMP降解率达89.5%。不同表面活性剂对THF-2降解DMP的影响存在差异。添加质量分数1%非离子表面活性剂曲拉通X-100和吐温80,对THF-2降解DMP有一定的促进作用,但差异不显著(p0.05);当曲拉通X-100和吐温80添加质量分数为2%和3%时,降解作用受到抑制,降解率与添加量呈显著负相关(r=-0.98,p0.05)。添加离子型表面活性剂十二烷基硫酸钠(SDS)会抑制THF-2对DMP降解作用。DMP降解试验表明,当DMP质量浓度为100~500 mg/L时,THF-2对DMP的降解符合一级动力学方程模型,降解半衰期为13.92~27.08 h。因此,菌株THF-2可应用于低温地区及低温条件下DMP的生物处理。

On the isolation,identification and characterization of DMP-degrading strain

The paper intends to introduce its experience on the isolation,identification and characterization of a DMP-degrading strain by taking di-methyl phthalate (DMP) as the carbon and energy source,which is named THF-2,from the rive sediments via the gradient pressure acclimatization.When we were successful in isolating the genomic DNA of the strain THF-2,we have managed to amplify and sequence its 16S rDNA fragment,thus,building up a phylogeny tree via MEGA 6.0,and the taxonomy of strain THF-2.Then,we have analyzed the factors that influence DMP-degradation of strain THF-2,including the culturing temperature,the initial pH value of the medium,and the amount of surfactants to be added,all of which has enabled us to make out the effect of the strain THF-2 growth on different PAEs,and the degrading effect of strain THF-2 on different concentration DMP.The results of our investigation and examination prove that the strain of THF-2 can be identified as Pseudomonas putida in accordance with 16S rDNA sequence analysis.What is more,THF-2 has been found enjoying nice degrading effect on DMP in a temperature range of 15-20 ℃,with the optimal temperature being 20 ℃℃ and the optimal initial growth pH =8.0.On the best condition,it is possible to degrade DMP (500 mg/L) effectively with THF-2 through an incubation process of 72 h,at the degrading rate of 89.5％.The effects of adding different surfactants on DMP-degradatian by strain THF-2 turn out to be various.For example,adding 1％ non-ionic surfactant Triton X-100 and Tween 80,the degradation effect of THF-2 on DMP can be promoted.On the other hand,adding 2％,3％ triton X-100 and Tween 80 can help to decrease the degradation effect of THF-2 on DMP.What is more,if the non-ionic surfactant were added over the rate of 2％,negative correlation (r =-0.98,p ＜ 0.05) would be found between the degradation rate and the surfactant content.Nevertheless,adding SDS tends to inhibit DMP being degraded by strain THF-2.Thus,the degradation experiments may suggest that,when DMP mass concentration ranges from 100 mg/L to 500 mg/L,the degradation of DMP by THF-2 tends to follow the first order kinetics equation model,with the degradation half-life time staying in a range from 13.92 h to 27.08 h.Therefore,it would be realistic to apply the strain THF-2 to DMP biodegradation practice in the cold status-in-situ.