生物表面活性剂产生菌的筛选及产物性能研究

筛选获得一株生物表面活性剂产生菌,经生理生化与16S r DNA鉴定,获得菌株为铜绿假单胞菌147(Pseudomonas aeruginosa 147)。发酵产物经过薄层色谱、红外扫描分析其发酵产物为糖脂类生物表面活性剂(Biosurfactant,BS),单因素最佳发酵条件优化为碳源、氮源和碳氮比分别为花生油、硫酸铵和25∶1,最佳培养温度为30℃,pH值为8,Na Cl浓度为5 g·L-1。在最佳条件下培养36 h,发酵液的表面张力值比原来降低了42.08 m N·m-1,且能平稳保持至144 h。在108 h细菌生物量最大,为2.63 g·L-1,此时产生的糖脂最多,可达2.02 g·L-1。生物表面活性剂对不同环数的多环芳烃类物质(荧蒽、芘、苯a]芘)的增溶效果实验表明:随生物表面活性剂添加量的增大,不同PAHs溶解度均增大;相同浓度生物表面活性剂添加条件下,高环多环芳烃(苯a]芘)的增溶效果低于低环多环芳烃(荧蒽、芘)。

Screening of a biosurfactant-producing bacterium and biosurfactant characteristics

A biosurfactant-producing bacterium was isolated and identified as Pseudomonas aeruginosa 147 by physiological and biochemi-cal characteristics and 16S rDNA sequencing. The fermentation products were assigned to glycolipid by Thin Layer Chromatography(TLC) and Fourier Transform Infared Spectroscopy(FT-IR)analysis. The optimal conditions for the strain to produce biosurfactants were peanut oil as initial carbon source,(NH4)2SO4 as nitrogen source, carbon to nitrogen ratio of 25∶1, pH 8, temperature of 30 ℃, and 5 g·L-1 NaCl. Un-der these conditions, the surface tension of the fermentation broths could be reduced by 42.08 mN·m -1, compared with the control, and stayed stable for 144 hours. During 108 hours of incubation, the bacterium achieved the maximum biomass(2.63 g·L-1)and had the maximum fermentation product(2.02 g·L-1). The solubilization of different polycyclic aromatic hydrocarbons(PAHs)(fluoranthene, pyrene, benzene a] pyrene)was increased with the addition of the fermentation products. At the same rates of fermentation products, enhanced sol-ubilization of PAHs with high-ring(benzene a] pyrene)was lower than that with low-ring(fluoranthene, pyrene).