生物表面活性剂产生菌的分离鉴定及碳氮源优化

Isolation of biosurfactant-producing bacteria and optimization of carbon and nitrogen sources

采集炼油厂内长期石油污染土壤,经富集培养、蓝色凝胶平板筛选和发酵液表面张力测定等方法,从油泥中筛选出产生物表面活性剂的土著微生物1株,命名为S2,并对其进行生理生化性能测定与产物特性及结构研究.结果表明,该菌鉴定为铜绿假单胞菌Pseudomonasaer uginosa,测定证明其发酵液表面张力稳定,最佳条件下发酵液表面张力可由75mN·m-1降至35mN·m-1,临界束胶浓度(CMC)值为0.25g·L-1,远远低于一般化学表面活性剂的CMC值.发酵液乳化性能优于对照的十二烷基磺酸钠(SDS)及十六烷基三甲基溴化铵(CTAB)等常用的化学表面活性剂.对培养基成分进行优化,选定的最佳碳源为菜油,最佳氮源为硝酸钠,优化培养条件后,产物最大产量达到了4.7g·L-1.

Microorganisms capable of producing biosurfactants were isolated by enrichment culture and blue agar plate based on the surface tension of the fermentation liquor. One indigenous microorganism,strain S2,which produced biosurfactants was isolated from oil sludge samples collected from Yangzi Refinery,Jiangsu Province,China. Its physiological morphology,growth,and the biosurfactant properties of the metabolite it produced were analyzed. Strain S2 was identified as belonging to Pseudomonas aeruginosa. The surface tension of its fermentation liquor is stable and can be lowered from initial 75 mN·m^ -1 to 35 mN·m^ - 1. The critical micelle concentration is 0.25 g·L^ -1 , which is much lower than normal chemical surfactants. The fermentation liquor is emulsified much better by the biosurfactant than by typical chemical surfactants such as SDS and CTAB. Furthermore, it is shown that the optimum carbon and nitrogen sources for the growth of the strain are vegetable oil and NaNO3 , respectively. Under these conditions, the production of biosurfactant by P. aeruginosa S2 can reach as high as 4.7 g·L^ -1