具有产表面活性剂功能石油降解茵的筛选及其发酵条件优化

从广州某炼油厂附近石油污染的土壤中筛选出一株可高效产表面活性剂的原油降解菌株MZ01，结合菌株形态观察、革兰氏染色和16SrDNA序列同源性进行分析鉴定其属于假单胞菌属（Pseudomonassp．MZ01），该菌9d对原油的降解率达54．7％。通过正交实验优化其产表面活性剂的环境因子并进行发酵培养，结果表明，MZ01最佳发酵条件为：酵母膏（3g·L^-1）作为氮源，玉米油（2g·L^-1）作为碳源，温度为25℃，pH值为9．0和含盐量为5％。该条件下3d的发酵产物经提纯后得到表面活性剂产量为2．27g·L^-1，测得该产物CMC值为0．1g·L^-1，可将水的表面张力从初始的72mN·m^-1降至30mN·m^-1。

Screening and Fermentation Optimization of a Biosurfactant-producing Oil-degrading Bacterium

The aim of the present study was to isolate oil-degrading bacterial strains with high ability to produce biosurfactants. Bacterial strains from oil contaminated soil near a refinery were enriched and incubated with oil as the sole carbon source. Bacterial strains to produce biosurfactants were then screened by testing oil collapse-dropping, emulsification index and surface tension, and those strains with the abili- ty to degrade oil were further screened by DCPIP tests. An oil-degrading bacterial strain MZ01 with high ability to produce biosurfactants was obtained. It was identified as Pseudomonas sp. MZ01 by gram-staining, morphology, and 16S rDNA sequencing. MZ01 could degrade crude oil by 54.7% within 9 days. The optimal conditions for MZ01 to produce biosurfactants were explored by orthogonal experiments. These conditions were yeast extract（ 3 g·L^-1 ） as nitrogen source, corn oil（ 2 g·L^-1 ） as carbon source, initial pH 9.0, 5% salinity and temper- ature 25 ℃. The production of biosurfactants by MZ01 was 2.27 g·L^-1 after 3-day fermentation. The critical micelle concentration（CMC） of the biosurfactants was 0.1 g·L^-1, reducing the surface tension of pure water from 72 mN· m^-1 to 30 mN· m^-1.