一株石油降解菌株的选育及其降解性能研究

Screening of a Petroleum Degrading Strain and Its Degradation Capability

毛海龙 鲁传涛 王宝元 王战勇

MAO Hai-Long LU Chuan-Tao WANG Bao-Yuan WANG Zhan-Yong

从辽河油田石油污染土壤中选育获得5株具有降解石油能力的菌株，编号为PD1301~PD1305。在培养时间4 d、石油质量浓度5.0 g/L、温度30℃、培养基起始pH值为7.0的条件下，PD1301~PD1305菌株对石油的降解率分别为57.7%、39.0%、44.4%、33.5%和21.8%，PD1301菌株的降解性能最好。经菌体形态特征、菌落培养特征、生理生化鉴定和16S rDNA基因序列分析，PD1301菌株形成的单菌落呈圆形，黄白色，中间微隆起，表面光滑无皱纹，菌株为革兰氏阴性杆菌，无芽孢和荚膜，具有浓青素产生能力，与铜绿假单胞菌（Pseudomonas aeruginosa）菌株的16S rDNA全序列的同源性为99%，初步鉴定为Pseudomonas aeruginosa。考察了培养时间、石油质量浓度、培养温度和培养基起始pH值对PD1301菌株降解石油的影响。结果表明，1~4 d内是菌株的对数生长期，菌株对石油的降解率显著提高，培养时间大于5 d后，降解率变化较小；菌株降解石油能力随着石油浓度的升高而降低，在石油加量为5.0 g/L时的降解率最高（58.6%）；随温度升高，降解率先增加后降低，30℃时达到峰值57.7%；随培养基起始pH值增大，降解率先增加后降低，pH值为7.0时的降解率可达59.4%。

Five petroleum degrading strains, named as PD1301—PD1305, were isolated from petroleum pollution soil in Liaohe oilfield. Biodegrading percentage of the best degrading strain PD1301 was 57.7% with 4 d cultivatable time, 30℃ cultivatable temperature, 7.0 initial pH value of culture medium and 5.0 g/L petroleum mass concentration, and that of PD1302—PD1305 was 39.0%, 44.4%, 33.5% and 21.8%. PD1301 was identified as Pseudomonas aeruginosa by thallus morphology analysis, colonies characterization, physiological reaction, biochemical reaction and 16S rDNA analysis. The single colony of PD1301 was round, yellow-white and slightly raised, and the surface of colony was smooth without wrinkles. PD1301 was a gram negative bacillus, which had no spore and capsule. PD1301 also could produce pyocyanin. The 16S rDNA sequence homology of PD1301 was similar with that of Pseudomonas aeruginosa by 99%. The effect of cultivatable time, cultivatable temperature, initial pH value of medium and petroleum concentration on degrading ability of strain PD1301 was studied. The results showed that the degrading rate was significantly increased at exponential phase (1—4 d), and there had small changes after cultured 5 d. With increasing petroleum concentration, the degrading capacity of strain showed a bell-shaped curve. The maximum value was 58.6% when petroleum mass concentration was 5.0 g/L. With increasing temperature, the degrading rate increased first and then decreased. The maximum value was 57.7% at 30℃ cultivatable temperature. With increasing initial pH value of culture medium, the degrading rate increased first and then decreased. The peak value was 59.4% when initial pH value was 7.0.