表面活性剂产生菌的筛选与优化及其产物性质的分析

从被石油污染的土壤中用蓝色凝胶培养基分离筛选出1株产糖脂类生物表面活性剂的菌株B2。经生理生化试验与16S r DNA序列分析将该菌株鉴定为沙雷氏菌属(Serratia sp.)。经红外光谱与薄层层析分析,结果表明该菌株产生的表面活性剂是一种鼠李糖脂。以发酵液的表面张力为指标,通过正交试验确定最佳发酵条件,即以20 g/L豆油为碳源、5 g/L尿素为氮源、温度34℃、p H 7.0、发酵时间96 h。在此最佳条件下测得表面活性剂的产量为3.746 1 g/L。该菌株所产表面活性剂水溶液在其浓度为临界胶束浓度时的表面张力为180 m N/m。

Analysis of Selection and Optimization of a Biosurfactant-producing Strain and Its Product Properties

A biosurfactant-producing bacteria, strain B2,was isolated by blue agar plate from the contaminated soil in Jilin oilfield. Through the analyses of physiological, and biochemical characteristics and 16S rDNA sequence, the strain B2 prelim-inarily identified as Serratia sp. The analysis recults of infrared spectral and thin-layer chromatography analysis indicated that the biosurfactant produced by strain was a kind of rhamnolipid. The surface tension of fermentation solution as the index, the optimum fermentation conditions were obtained by orthogonal test. The optimum fermentation conditions were 20 g/L soybean oil as carbon source,5 g/L urea as nitrogen source,temperature of 34℃, pH of 7.0 and fermentation time of 96 h. Under the optimal fermentation conditions, the yield of biosurfactant produced by the strain could reach 3.746 1 g/L. The critical micelle concentration of biosurfactant solution was 180 mN/m.