土壤中多环芳烃微生物降解能力模拟

摘要

为了揭示微生物菌种(组合)对土壤中PAHs(多环芳烃)降解率的影响以及不同类型PAHs抗微生物降解能力的差异,分析了北京市6个不同环境功能区土壤中微生物种类及其分布特征,从中筛选出部分微生物菌种对典型PAHs和原油进行降解模拟试验,对比分析微生物对不同PAHs降解能力的差异.结果表明:①不同菌种组合对PAHs的降解能力存在明显差异,与假单胞菌属、无色杆菌、短稳杆菌混合菌相比,假单胞菌属、无色杆菌、短稳杆菌和微杆菌混合菌对PAHs的降解率高0.6％～4.5％;②在相同降解条件下,不同PAHs的降解率存在明显差异,在单体培养基中,LMW PAHs(低环数PAHs)的降解率在25.3％以上,而HMW PAHs(高环数PAHs)的降解率都小于20.1％;③在单体培养基与混合培养基中PAHs的降解能力也存在一定差别,单体培养基中PAHs的降解率较混合培养基中高4.2％ ～26.6％;④无论在单体培养基中,还是混合培养基中这些化合物的降解率均存在随着降解时间的增加而增大的现象;⑤在原油培养基中不同PAHs的降解率更为复杂,并且出现了中低分子量PAHs降解率随降解时间增加反而降低的假象,这可能是由于随着时间增加,微生物对PAHs的降解能力加强,原油中含烷基的PAHs基团降解或HMW PAHs被微生物降解产生LMW PAHs中间产物造成.研究显示,假单胞菌属、无色杆菌、短稳杆菌和微杆菌对HMWPAHs和LMW PAHs均有明显的降解效果,但不同PAHs的降解率存在明显的差异,即使是同一单体化合物,在单体培养基、混合培养基和原油培养基三种不同的降解条件下,其降解率也具有不同程度的差别.%In order to reveal and understand microbial degradation efficiency for polycyclic aromatic hydrocarbons (PAHs) in soil,microbial species and distribution characteristics were evaluated for six different environmental functional soils in Beijing.Several microbial strains were screened to simulate PAHs and crude oil degradation experiments and discuss the difference in microbial degredation ability for PAHs.The results showed that there were obvious differences in the ability of microbial degradation between different combinations of microbial strains.Bacteria consortium of Pseudomonas sp.,Achromobacter sp.,Empedobacter sp.and Microbacterium showed a higher efficiency in degradation for PAHs than bacteria consortium of Pseudomonas sp.,Achromobacter sp.and Empedobacter sp..Under the same degradation conditions,the degradation efficiency for different PAHs monomer compounds were obviously different;in the single medium,the degradation rate for low-molecular weight (LMW) PAHs was bigger than 25.3％,but the degradation rate for high-molecular weight (HMW) PAHs was less than 20.1％.Degradation ability differences between single medium and mixed medium were also observed;the degradation rate of PAHs in the single medium was 4.2％-26.6％ higher than that in the mixed medium.It is a common phenomenon that the degradation rate increases with degradation time in the single and mixed medium.Significant differences in degradation ability between crude oil medium and PAHs medium could be obtained for PAHs monomer compounds in the oil medium,indicating the degradation efficiency is much more complicated,including because of the longer degradation time and the lower degradation ratio of middle and low molecular weight PAHs.The degradation ability of HMW PAHs increased with the degradation time,and the LMW PAHs formed as an intermediate produced by the PAHs with alkyl groups or HMW PAHs.The results revealed that LMW PAHs and HMW PAHs can be effectively degraded by Peudomonas sp.,Achromobacter sp.,Empedobacter sp.and Microbacterium with different degradation efficiency.Even for the same PAHs monomer compound in the single medium,mixed medium or the crude oil medium,the degradation efficiency differs.