Screening and the Degradation Conditions of Pyrene-degrading Bacterium

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%.Cd2+(100 mg·L-1) was toxic to the bacterial strain,Cu2+(50 mg·L-1) could partially inhibit the growth of strain B4,Zn2+(100 mg·L-1) and Pb2+(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.