培养条件对产油微生物生长的影响

Effect of culture conditions on cell growth and lipid accumulation of oleaginous microorganism

摘要:

为了筛选出高产油菌株, 首先采用细胞形态学方法与细胞化学方法(苏丹III染色法)对4株高产油脂菌株进行初筛, 并通过索氏提取法对初筛菌株油脂含量进行分析, 确定M2菌株为实验菌株, 其油脂含量达53.09%。为了增加产油微生物油脂产量, 本试验考察了不同发酵条件对其细胞生长和油脂积累的影响。优化工艺参数为: 10° Bx玉米皮渣水解液为培养基质, 0.2% NaNO3为氮源, pH 6.0、28oC下发酵培养6 d, 微生物油脂含量75.21%, 菌体生物量30.40 g/L, 油脂产量22.86 g/L。气相色谱分析表明该油脂的脂肪酸组成与植物油相似, 主要含有16碳和18碳系脂肪酸, 可作为生物柴油的原料, 不饱和脂肪酸含量达68%, 可应用于医药化工领域。

关键词:微生物油脂, 玉米皮渣, 生物柴油

Abstract:

We used four strains (Y1, Y2, M1 and M2) to screen out the high lipid production strains. We first adopted cell morphology and cytochemical methods (Sudan III dyeing technique) to observe intracellular characteristics. Observation results indicated that M2 strain had the potential lipid accumulation capacity. To prove this, lipid content of these strains was determined by soxhlet extraction. One strain (M2) was found to produce lipids up to 53.09%. In order to increase the production of oleaginous microorganism, the effects of hydrolysate concentration, nitrogen source, pH, fermentation temperature and time on cell growth and lipid accumulation were studied. The optimal fermentation conditions were obtained as follows: corn starch byproduct hydrolysate concentration at 10°Bx as carbon source; NaNO3 as nitrogen source at 0.2%; initial pH of 6.0; temperature at 28oC, cultivated for 6 d. Under these conditions, M2 strain accumulated lipids up to 75.21% on a cellular biomass basis with biomass yield of 30.40 g/L, and the corresponding lipid production reached 22.86 g/L. GC analysis demonstrated that the fatty acid composition of the lipid was similar to that of vegetable oil, which mainly contained 16-and 18-carbon fatty acids. Thus, microbial lipid is a promising material for biodiesel production, and its unsaturated fatty acid content reached around 68%. These unsaturated fatty acids show great potential applications in food, medicine and cosmetics industries.

Key words:microbial lipids, corn starch byproduct, biodiesel