近几年随着化工、汽车工业的高速发展，石油作为一种重要的化石能源被广泛应用。由于管理的疏漏等原因，造成环境中多环芳烃在土壤环境，水环境及大气中的污染严重，利用高效降解菌进行PAHs污染物的降解具有降解效果好、安全、成本低不造成二次污染等优点，是比较理想的一种环境友好型降解方法，因此前景十分广阔。在多环芳烃的16种物质中，苯并[a]芘具有强烈的致癌、致畸、致突变毒害作用，并且其生物可利用性低。目前针对苯并[a]芘的高效降解菌株已有很多报道，但对于微生物降解苯并[a]芘的微观机制尚不明确，而吸附摄取过程作为苯并[a]芘降解过程的重要步骤和初始环节，因此研究微生物吸附摄取苯并[a]芘的微观机制具有重要意义。本实验选取课题组前期从大港油田和北京焦化厂长期污染土壤中筛选出的12株的多环芳烃高效降解菌株，在苯并[a]芘为单一底物的条件下培养15天，从中选取降解效率较高的2株苯并[a]芘降解菌株作为研究靶细菌。经16S rDNA鉴定分别为红球菌和假单胞菌。在不同浓度苯并[a]芘条件下培养，结果显示2株菌在培养期内均可分泌生物表面活性剂，以假增溶的方式摄取苯并[a]芘。从培养上清液中提取2株菌分泌的生物表面活性物质，采用薄层色谱层析法和莫氏试剂显色反应，以及红外光谱图分析提取样品糖类和酯类的吸收峰，最终推测红球菌CmLB13分泌的生物表面活性剂为海藻糖脂，假单胞菌DG17分泌的生物表面活性剂为鼠李糖脂。通过测定培养上清液中蛋白质含量变化，研究微生物分泌双加氧酶的含量变化。相比假单胞DG17蛋白含量，红球菌CmLB13培养上清液中蛋白含量较高，细菌在好氧代谢过程中分泌胞外降解酶降解苯并[a]芘，并且酶的含量与2株菌的生物量密切相关。研究微生物是否通过改变细胞疏水性吸附于疏水底物上摄取苯并[a]芘。不同浓度苯并[a]芘条件下，红球菌CmLB13的细胞疏水性在3mg/L时达到最大值26%，而假单胞菌DG17的细胞疏水性随苯并[a]芘浓度升高而增大。苯并[a]芘浓度高于10mg/L条件下，假单胞菌DG17可以通过改变表面疏水性的方式摄取疏水性底物。研究加入鼠李糖脂对假单胞菌DG17菌体疏水性影响。加入50mg/L鼠李糖脂，假单胞菌DG17的生物量相比较于未加入鼠李糖脂的假单胞菌DG17培养菌体表面最大疏水性有明显提高，鼠李糖脂能够增加假单胞菌DG17细胞表面疏水性，进而促进假单胞菌DG17对疏水底物的吸附摄取。通过扫描电镜观察红球菌CmLB13细胞表面形态发现，苯并[a]芘驯化培养的红球菌CmLB13细胞表面粗糙且凹凸不平，可能是由于细胞疏水性改变或毒害作用造成。

In the past few years, with the high speed development of chemical industry and auto industry, oil has been widely used as a kind of important fossil energy. Because of management oversight, PAHs in soil, water and air is serious. Use high efficiency degradation bacterium in the degradation of pollutants, it has good degradation effects, safe, low cost and not cause secondary pollution, etc. It is a relatively ideal environment friendly degradation method.In 16 kinds of PAHs, benzo[a]pyrene has strong carcinogenic, teratogenic and the mutation poisonous effect. At present, there have many reports about high efficiency degradation bacterium of benzo[a]pyrene. But the microscopic mechanism of microbial degradation benzo[a]pyrene is not clear. The adsorption and uptake is important step and initial link in degradation of benzo[a]pyrene. So study of the microscopic mechanism of adsorption uptake of benzo[a]pyrene by microbe has important significance.In this experiment, I select 12 bacterial strains from contaminated soil in Dagang oil field and Beijing coking plant. Bacteria culture under condition of benzo[a]pyrene for 15 days. Choose the two strains of benzo[a]pyrene high degradation efficiency bacterium as research target bacteria. The 16S rDNA appraisal for Rhodococcus sp. and Pseudomonas sp. Bacteria culture under different concentration of benzo[a]pyrene, the experimental results show that the two strains bacteria secrete biosurfactant, it can absorb benzo[a]pyrene with solubilizing pattern. Research the biosurfactant type. Extract the biosurfactant from two strains secreted by two strains. With thin layer chromatography and mok's reagent reaction and FI-IR, it research that rhodococcus CmLB13 secrete seaweed glycolipid, pseudomonas DG17 can secrete rhamnolipid.I assay the protein content changes in supernate. The results show that protein level is higher in rhodococcus CmLB13 supernate than in pseudomonas DG17 supernate, it can conjecture that bacterium can secrete degradative enzyme, and the enzyme content is closely related to biomass of two strains bacteria.Microorganism could adsorp on hydrophobic substrate to uptake of benzo[a]pyrene by change of cell hydrophobicity. The result proves that hydrophobic of rhodococcus CmLB13 maximizing in 3mg/L, but hydrophobic of pseudomonas DG17 rised along with concentration of benzo[a]pyrene. It can conjecture that pseudomonas DG17 can adsorp on hydrophobic substrate to uptake of benzo[a]pyrene by change of cell hydrophobicity.Research rhamnolipid affect hydrophobicity of DG17. The results show that biomass liveweight is highest in 50mg/L rhamnolipid, it’s higher than in condition of no rhamnolipid. It explaind that rhamnolipid can increase the hydrophobicity of DG17. Observe the cell surface morphology of rhodococcus CmLB13 by scanning electron microscope. The cell surface coarse and uneven under benzo[a]pyrene, it is due to cell hydrophobic change and poison effect.