广谱碳源产油酵母菌的筛选

对10株酵母菌利用不同单糖为碳源条件下菌体内积累油脂的能力进行了初步考察,并对菌油进行了分离和脂肪酸组成分析。实验发现,以葡萄糖为唯一碳源时有9株菌油脂含量超过自身细胞干重的20%,可以界定为产油微生物。其中6#菌(T.cutaneumAS2.571)利用葡萄糖发酵菌体油脂含量达到65%(W/W)。所有实验菌株都能同化多种单糖,其中1#菌(L.starkeyiAS2.1390)、4#菌(R.toruloidesAS2.1389)和11#菌(L.starkeyiAS2.1608)表现出对碳源利用的广谱性,能转化五碳糖木糖和阿拉伯糖并在菌体内积累油脂,油脂含量最高达到26%。脂肪酸组成分析结果表明,菌油富含饱和及低度不饱和长链脂肪酸,其中棕榈酸、油酸和亚油酸三者之和占总脂肪酸组成的90%以上,脂肪酸组成分布类似于常见的植物油。这些结果对利用产油微生物转化木质纤维素水解混合糖获取油脂资源的研究具有重要意义。

Screening of Oleaginous Yeasts for Broad-Spectrum Carbohydrates Assimilating Capacity

Described herein are preliminary screening studies on ten yeast strains for assimilation broad-spectrum carbohydrates to produce microbial lipids. It was found that nine of them accumulated lipids over 20% of their biomass using glucose as sole carbon source under nitrogen-limited culture conditions. Therefore, these strains can be defined as oleaginous yeast. One strain, namely, T. cutaneum AS 2.571, produced lipids up to 65% (W/W) of its biomass. Strains L. starkeyi AS 2.1390, R. toruloides AS 2.1389 and L. starkeyi AS 2.1608 showed excellent metabolising capability on hexoses as well as D-xylose and L-arabinose, two major pentoses presented in lignocellulosic biomass, to produce lipids up to 26%. These yeasts can be further genetically modified and used to produce oils in closed manufacturing systems, and the process can be engineered for better performance. Gas chromatography analysis of microbial lipids revealed that major constituent fatty acids were palmic acid, oleic acid and linoleic acid, three of which collectively took over 90%. Such compositional feature was quite similar to rapeseed oil, one of the widely used feedstock for biodiesel. Therefore, oleaginous yeasts could be considered as ideal hosts for fermentation of mixed sugar from lignocellulosic biomass for renewable energy development.