芘降解菌株的筛选及降解条件的研究

Screening and the Degradation Conditions of Pyrene-degrading Bacterium

为了筛选高效多环芳烃芘的降解菌株并研究其降解条件,为生物修复多环芳烃污染土壤提供科学依据和实验材料,从长期受石油污染土壤中分离筛选得到一株芘降解菌B4,初步鉴定为假单胞菌属(Pseudomonassp.)。并采用室内培养方法,研究了该菌株降解芘的特性及各种环境条件对降解效能的影响。结果表明,菌株B4在28℃振荡培养条件下,对50mg.L-1的芘降解率为91.70%,芘的降解与细菌数量的增长呈正相关关系。加入水杨酸(50mg.L-1)作为共代谢底物,降解率可达到95.55%。当pH为4、盐浓度高于5%时,菌株B4不生长。对菌株B4在重金属离子胁迫下对芘的降解研究发现,在一定浓度下,Pb2+与Zn2+的存在对B4的降解效能影响较小,Cu2+对菌株的生长具有一定的抑制作用,Cd2+对菌株B4有毒性。

Elevated concentrations of polycyclic aromatic hydrocarbons （PAHs） have been found in soils due to petroleum pollution, and microbial degradation has been suggested as the best way to remove PAHs from contaminated soils. One pyrene-degrading bacterium （B4） was isolated from petroleum contaminated soil. The bacterial strain was identified as Pseudomonas sp. based on its morphological and biochemical characteristics. The degradation of pyrene by bacterial strain B4 and the effects of salinity, pH, heavy metals and the co-metabolism substrates such as glucose and salicylic acid on biodegradation potential were also investigated. The results showed that the bacterial strain B4 had a potential of pyrene degradation, with the degradation rate of pyrene 91.70% when the pyrene concentration was 50 mg· L^-1 in solution culture. A significantly positive correlation was found between bacterial growth and pyrene degradation. The bacterial growth was inhibited when pH was 4 or salinity was 8%. Cd^2＋ （100 mg· L^-1） was toxic to the bacterial strain, Cu^2＋ （50 mg· L^-1） could partially inhibit the growth of strain B4, Zn^2＋ （100 mg· L^-1） and Pb^2＋ （200 mg·L^-1） had no significant influence on the bacterial growth. The degradation rate of pyrene could reach 95.55% under salicylic acid （50 mg· L^-1） co-existing with pyrene. The addition of glucose （50 mg· L^-1） had a little inhibition influence on growth of bacterial strain B4 and biodegradation of pyrene. These results may provide scientific theories and effective PAHs-degrading bacteria for bioremediation of PAHs contaminated soils.