假单胞菌XD-1(Pseuomonas XD-1)的产表面活性剂性能研究

Study on the Pseuomonas XD-1 releasing biosurfactants

从含油废水中分离到1株表面活性剂产生菌,经鉴定为假单胞菌(Pseuomonassp.),命名为XD 1.对假单胞菌XD 1的产表面活性剂性能进行研究,实验结果表明,在正交优化的培养基中发酵培养时,菌XD 1可将培养液的表面张力从70 0mN·m-1降至30 2mN·m-1,其产表面活性剂方式为生长相关型;经提取分析,菌XD 1所产表面活性剂为脂肽类和糖脂类物质的混合物,脂肽类物质为主要成分;菌XD 1所产表面活性剂的CMC值为50mg·L-1,在pH=6 0时表面活性剂表现出最佳活性;菌XD 1所产表面活性剂主要积累在胞内特定的细胞器中,并在细胞壁上产生一层粘附的表面活性剂膜,膜厚140nm,在生长过程中,菌体会将细胞器和细胞壁上的表面活性剂释放到胞外.将培养72h的菌体浸入双蒸水中,6h后菌体能把积累在细胞器和细胞壁上的表面活性剂释放到水体中.

A bacterium XD-1 with petroleum as carbon source and biosurfactant as product was isolated from oil-containing wastewater and identified as Pseuomonas sp.. The capability and mechanism of strain XD-1 releasing biosurfactant had been studied. The experimental results indicated that the strain XD-1 gradually synthesized and released biosurfactant during growth with reducing the surface tension from 70?mN·m^(-1) to 30.2?mN·m^(-1) when incubated in the fermentative medium that was optimized by orthogonal experiment. The strain started to produce biosurfactant in its logarithmic growth period and ceased in the stabilization period. Hence, the model of growth-correlativity of the strain XD-1 releasing biosurfactant was proposed. Through extraction and infrared spectrum analysis, the effectual components of the biosurfactant released by the strain XD-1 were determined to be the mixture of lipo-peptide and gly-peptide, in which lipo-peptide played the leading role in reducing surface tension. The CMC value of the biosurfactant was 50?mg·L^(-1), and the lowest surface tension caused by the biosurfactant appeared at pH 6.0. The experiment of the biosurfactant distribution showed that it accumulated in the special organelle of the cell, and atomic force microscopy image examination demonstrated that a viscous biosurfactant film with about140nm thick was produced on the cell wall. The strain XD-1 released the biosurfactant from the organelle and cell wall out of the cell in its growth. The research also approved that petroleum could stimulate the strain to secrete biosurfactant more rapidly. After the strain grew for 72?h, and then was dipped in ddH_2O for 4 hours,it quickly released biosurfactant into the water and hence reduced the surface tension of the water, while the strain could start to release biosurfactant accumulated from organelle and cell wall at the beginning of the experiment if the strain was dipped in ddH_2O with drops of petroleum in it. And the highest releasing amount was reached after 6 hours of dipping in the both circumstances.