响应面法优化石油降解菌性能的研究

Study on petroleum-degrading bacterium and its optimization using response surface methodology

从延长油田石油污染土壤中筛选出4株能以原油为唯一碳源生长的细菌单菌株,鉴定其优势菌株YC-2为枯草芽孢杆菌;利用响应面法进行实验设计,选定培养温度、p H值、氮磷比以及盐度为影响因素,对原油含量为0.5%的培养基进行YC-2菌株降解工艺优化,得到了原油降解率与4种因素之间的非线性回归方程,确定了降解原油的最优工艺条件:培养温度28℃;p H值6.5,氮磷比5.2∶1,盐度0.45%。在最优条件下,预测降解率为53.9%,实验验证值为52.5%,结果显示,建立的模型具有较高的精度。

Four species of oil-degrading bacteria that use crude oil as their carbon source were screened and isolated from petroleum-contaminated soils in the Yanchang oil field. The dominant bacteria,YC-2,was identified as Bacillus subtilis. The oil removal rate of this strain was highly dependent on various influencing parameters. Response surface methodology（ RSM） was employed to optimize some factors,such as the culture temperature,pH value,rate of nitrogen and phosphorus,and the salinity of medium,to enhance the biodegradation process. The non-linear regression equation that described the relationship between the oil removal rates and the above-mentioned factors in 0. 5% petroleum was obtained. The optimum process parameters for oil removal rates were determined as the following： an incubation temperature of 28 ℃,a pH value of 6. 5,the rate of nitrogen and phosphorus as 5. 2∶ 1,and a medium salinity of 0. 45%. Under these optimum conditions,the predicted oil removal rate was 53. 9%,whereas the observed value was 52. 5%. In addition,experimental results showed that the proposed model had higher accuracy.