产生物表面活性剂耐盐菌的筛选鉴定及其对石油污染盐渍化土壤的修复作用

为得到高效产生物表面活性剂耐盐菌，从黄河三角洲石油污染盐渍化土壤中分离出41株细菌，经测定发酵液排油活性、表面张力和乳化值（EI24），得到1株高效产生物表面活性剂耐盐菌BF40.通过形态、生理生化特征和16S rDNA序列分析，确定该菌为沙雷氏菌（Serratia sp.）.通过液体培养试验，研究了BF40的耐盐特性和降解原油能力，并通过室内土壤培养试验研究了BF40及其产生的生物表面活性剂对石油污染盐渍化土壤的修复作用.结果表明，在含5~70 g·L^-1NaCl液体培养基中BF40生长良好，属中度耐盐菌.BF40能有效利用原油，在含10 g·L^-1NaCl液体培养基中培养7d，原油降解率达到56.7%.添加BF40产生的生物表面活性剂或接入BF40能明显促进盐渍化土壤石油烃的降解，修复60 d，土壤石油去除率与对照相比分别提高了24.6%和13.4%.接种BF40能降低土壤溶液表面张力，明显提高土壤脱氢酶活性，更能有效促进沥青质降解.添加生物表面活性剂土壤脱氢酶活性与对照相比没有显著差异，但更能有效降低土壤溶液表面张力，促进饱和烃降解，表明接种BF40和添加生物表面活性剂可能对促进石油污染盐渍化土壤的生物修复存在不同作用机制.

Isolation and identification of halotolerant biosurfactant-producing bacteria and its application in bioremediation of petroleum-contaminated saline soil

To obtain efficient halotolerant biosurfactant-producing bacteria, 41 bacteria strains were isolated from 36 petroleum contaminated saline soil samples in the Yellow River Delta. Based on the emulsification, surface tension and oil-spreading diameter of culture supernatant, one halotolerant bacterium (strain BF40), which can produce biosurfactant efficiently, was screened. According to morphological, physiochemical characteristics and 16S rDNA sequence, this strain was identified as Serratia species. In the liquid cultures, characteristic of halotolerant and ability of crude oil degradation of strain BF40 were observed. At the same time, the effects of BF40 inoculating and its biosurfactant application in petroleum degradation in saline soil were investigated. Results showed that strain BF40 grew well at NaCl concentrations ranging from 5 g·L^-1 to 70 g·L^-1. 56.7% of crude oil added was degraded in a liquid culture medium containing 10 g·L^-1 NaCl in 7 days. Compared with the control treatment, biosurfactant application and BF40 inoculating could increase petroleum hydrocarbon by 24.6% and 13.4% in saline soils, respectively, after 60 days. BF40 inoculating reduced soil solution surface tension, increased dehydrogenase activity, and promoted asphaltene degradation effectively. Biosurfactant reduced soil solution surface tension and boosted saturated hydrocarbon degradation. However, compared with the control, soil dehydrogenase activity increased insignificantly. Hence, we conclude that BF40 inoculating and biosurfactant application accelerate saline soil remediation through different mechanisms.