一株产脂肽类表面活性剂的碱性Dietzia菌及特性研究

【目的】筛选降解性能良好的产生物表面活性剂的菌株,对其进行分类学鉴定,确定所产表面活性剂物质并对各影响因素进行评价。【方法】利用液体石蜡为底物筛选降解性能良好的产生物表面活性剂菌株,通过形态特征观察、生理生化测定、16S rRNA基因序列分析等实验确定菌株的分类地位。通过排油圈活性、表面张力值、薄层层析等方法确定生物表面活性剂的性质,分析碳、氮源和温度、pH、盐浓度各因素对菌株产生物表面活性剂的影响。【结果】从大连新港采集的样品中分离得到一株产表面活性剂的嗜碱菌株3372,经分类鉴定表明其是Dietzia cercidiphylli的新菌株。嗜碱菌3372发酵液粗提物的排油直径为6.1 cm,表面张力可从67.62 mN/m降到32.95 mN/m,经薄层层析分析,初步鉴定为脂肽类表面活性剂。综合各因素对发酵液表面活性的影响,菌株3372在pH为9.0、适盐浓度为3%的培养基中,经30°C培养可将发酵液表面张力值降到最低。【结论】嗜碱菌3372是脂肽类生物表面活性剂产生菌的新成员,其在高盐碱条件下产生表面活性剂的特性在工业应用上有一定的潜力。

Characterization of an alkaliphilic biosurfactant- producing strain of Dietzia

Objective] Isolating and characterizing biosurfactant-producing bacteria. Methods] Biosurfactant-producing bacteria were isolated by enrichment method. The morphological, biochemical and physiological characteristics and 16S rRNA gene sequence were determined to identify the taxonomic position of strain 3372. The optimal conditions for the growth and biosurfactant production of strain 3372 were investigated. Results] Strain 3372 was isolated from marine water sample. It grows from pH 7.0 to 11.0 (optimum at pH 9.0), from 10 °C to 45 °C (optimum at 30 °C) and up to 12 % salinity. 16S rRNA gene sequence analysis showed that the strain belonged to the genus Dietzia and most closely related to Dietzia cercidiphylli. Strain 3372 was able to grow and reduce the surface tension of culture broth to 32.95 mN/m when cultured using paraffin as sole carbon source at pH 9.0 and 3% salinity. The biosurfactants produced by strain 3372 was identified as lipopeptides by thin layer chromatography. Conclusion] Strain 3372 was a new alkaliphilic member of lipopeptides-producing bacteria, which has potential application in the processes where high pH is common.