嗜盐碱高环PAHs降解菌的分离及其降解特性研究

Isolation and degradation characteristics of haloalkaliphilic high molecular-weight polycyclic aromatic hydrocarbon-degrading bacteria

为获取嗜盐碱高环多环芳烃(Polycyclic aromatic hydrocarbons,PAHs)降解菌,并研究其降解特性,利用盐度为5%、pH为8.6的无机盐培养液从延长油田石油污染土壤中富集分离出6株能以芘为唯一碳源和能源的嗜盐碱菌SYP-1、SYP-2、SYP-3、SYP-4、SYP-5和SYP-11。经形态学观察、生理生化特征分析和16S rRNA基因序列对比对菌株进行了鉴定,确定SYP-1为代尔夫特菌属(Delftia sp.),SYP-2、SYP-4和SYP-11为海杆菌属(Marinobacter sp.),SYP-3和SYP-5为芽孢杆菌属(Bacillus sp.)。初步的降解能力试验表明,6株降解菌7 d内可使初始浓度为50 mg·L^-1的芘降解率达42.3%~68.8%,使初始浓度为5 mg·L^-1的苯并[a]芘降解率达27.0%~49.4%。经耐盐碱特性分析,株菌SYP-1、SYP-2、SYP-3和SYP-11的可生长盐度范围为0~20%,SYP-4和SYP-5的可生长盐度范围为0~15%,6株菌均可在pH为5~10的环境中生长。选择了对芘和苯并[a]芘同时具有较高降解能力的4株菌SYP-2、SYP-3、SYP-4和SYP-11,分析了其在不同盐度和pH条件下对芘降解效率的影响,结果表明,无论在0~15%的盐度范围内还是在5~10的pH范围内,4株菌对芘均具有良好的降解效果。研究表明,所分离菌株具有较高的耐盐碱性,且对降解4环以上高环PAHs具有很大潜力。

To obtain the haloalkaliphilic high molecular-weight polycyclic aromatic hydrocarbon(PAH)-degrading bacteria and study their degradation characteristics, six haloalkaliphilic strains(SYP-1, SYP-2, SYP-3, SYP-4, SYP-5, and SYP-11)were isolated from oilpolluted soil in the Yanchang oilfield with pyrene as the sole carbon and energy source in a mineral salt medium with a salinity of 5% and a pH of 8.6. Based on morphological observations, physiochemical characteristics, and 16 S rRNA sequences analysis, SYP-1 was identified as Delftia sp.;SYP-2, SYP-4, and SYP-11 were identified as Marinobacter sp.;and SYP-3 and SYP-5 were identified as Bacillus sp. A preliminary degradation ability experiment showed that 42.3%~68.8% of pyrene with an initial concentration of 50 mg·L^-1 was degraded and 27.0%~49.4% of benzo(a)pyrene with an initial concentration of 5 mg·L^-1 was degraded by the six degrading strains in 7 days. Four strains(SYP-2, SYP-3, SYP-4, and SYP-11)with high degradation ability for pyrene and benzo[a]pyrene were selected to analyze the effects of different salinity and pH on the degradation efficiency of pyrene. In the range of 0~15% salinity or pH range of 5~10, all four strains showed efficient degradation ability of pyrene. Thus, the isolated strains have high salinity and alkali resistance, and great potential to degrade high molecular weight PAHs above four rings.