芽孢杆菌ZG0427表面活性剂性质及对石油降解菌的作用

Characterization and its effect on oil-degradation bacteria of biosurfactants produced by a Bacillus sp.ZG0427

为研究生物表面活性剂对石油降解菌的作用效果,采用酸沉法从芽孢杆菌(Bacillus sp.)ZG0427培养液中提取了生物表面活性剂,用薄层层析方法对其类型进行鉴定,并测定了带电性质及乳化性能。分别将芽孢杆菌ZG0427菌体和表面活性提取物加入石油降解假单胞菌(Pseudomonas sp.)YM15及红平红球菌(Rhodococcus erythropolis)KB1培养物中,研究其对石油降解菌生长及石油降解效果的影响。结果表明,芽孢杆菌ZG0427所产表面活性剂为脂肽类阴离子表面活性剂。当表面活性剂水溶液质量浓度为100 mg/L时,其乳化指数可达到58.0%。当ZG0427与YM15混合培养时石油降解率从32.70%提高到39.33%;与KB1混合培养时,石油的降解率从19.98%提高到34.33%。当在石油降解菌中添加不同质量浓度表面活性剂提取物后,不仅促进了假单胞菌YM15的生长,还能明显增加其石油降解效率(p<0.05),在培养基中添加20 mg/L表面活性剂提取物,培养第5 d时,YM15菌落数达到2.5×1012CFU/m L,对石油的降解率为40.07%。生物表面活性剂产生菌ZG0427与石油降解菌KB1及YM15构成的复合菌剂对石油有良好的降解效果,但高剂量表面活性剂对KB1生长产生了不同程度的抑制作用,导致石油降解率降低。

The purpose of this paper is to introduce a new method to enhance the oil degradation efficiency. The biosurfactant producing bacterium Bacillus sp. ZG0427 was cultivated in the fermentation broth at 37 ℃ for 34 h. The biosurfactant was partially purified from the supernatant of the bacterial culture by acid precipitation method. The properties of the biosurfactant were determined by thin layer chromatography and electric property determination,respectively,and the emulsification of the biosurfactant was also determined. In order to study the effect of the biosurfactant on oil degrading bacteria,the bacterial cells of Bacillus sp.ZG0427 and its biosurfactant were added into the media of oildegradation bacteria Pseudomonas sp. YM15 and Rhodococcus erythropolis KB1 respectively,and cultivated at 30 ℃ with shaking at 160 r/min for seven days. The effects on the bacterial cell growth were monitored with the spread plate count method. The oil degradation rates were determined by measuring the weight of the residual crude oil extracted from the supernatant of the bacterial cultures. The results showed that the biosurfactant produced by strain ZG0427 was identified as a lipopeptide anionic biosurfactant,with the emulsifying index of 58. 0%. The oil degradation rate of Pseudomonas sp. YM15 was increased from 32. 70%to 39. 33%,with the rise of 6. 63% when co-cultured with Bacillus sp. ZG0427. The oil degradation rate of R. erythropolis KB1 was increased from 19. 98% to 34. 33%,with the increasing of14. 35% when co-cultured with Bacillus sp. ZG0427. Addition different amount of the extracted biosurfactant promoted the growth of Pseudomonas sp. YM15,and enhanced the oil degradation efficiency（ p 0. 05）. When the concentration of the biosurfactant was increased to 20 mg/L,the number of bacterial colonies reached to 2. 5 × 1012 CFU/m L after 5 days and the oil degradation rate reached at 40. 07%. The above results prove that the mixtures of biosurfactant bacteria ZG0427 and the oil degradation bacteria KB1 and YM15 can obviously increase the oil degradation rate. However,the high-dose biosurfactants could inhibit the growth of R. erythropolis KB1,and resulted in the decreasing of oil degradation rate.