发酵性丝孢酵母HWZ004利用水稻秸秆水解液发酵产油脂

Using rice straw hydrolysate for microbial oil production by Trichosporon fermentans HWZ004

摘要:

为高效利用水稻秸秆中的纤维素和半纤维素产油脂，采用稀酸预处理和酶水解两步法对水稻秸秆进行水解，然后以水解液为碳源，培养发酵性丝孢酵母Trichosporon fermentans HWZ004产微生物油脂。结果表明，经简单overliming法脱毒后水稻秸秆水解液中乙酸、糠醛和5-羟甲基糠醛的浓度分别为0.4 g/L、0.1 g/L和0.05 g/L。只需添加少量氮源和微量CuSO4?5H2O，该水解液即可满足T. fermentans HWZ004发酵产油脂的要求。发酵最适接种量、初始pH和温度分别是5.0％、7.0和25 ℃。T. fermentans HWZ004在优化条件下培养7 d的生物量、油脂含量和油脂产量分别是26.4 g/L，52.2％和13.8 g/L；油脂得率系数为17.0，大大高于驯化前菌株T. fermentans CICC 1368在脱毒水稻秸秆半纤维素水解液中的对应值 (11.9)。所产油脂的脂肪酸组成与植物油相似，不饱和脂肪酸含量达70％以上，宜作为生物柴油的生产原料。

Abstract:

To efficiently use both cellulose and hemicellulose for lipid production, rice straw was hydrolyzed by a two-step process including dilute acid pretreatment and then enzymatic hydrolysis, and the hydrolysate was used as carbon source for lipid fermentation by Trichosporon fermentans HWZ004. After a simple overliming, the concentrations of acetic acid, furfural and 5-hydroxymethyl-furfural were 0.4 g/L, 0.1 g/L and 0.05 g/L, respectively. The hydrolysate could be used for lipid fermentation with T. fermentans HWZ004 without adding other nutrients except for a small amount of nitrogen source and trace CuSO4?5H2O. The optimum inoculum size, initial pH and temperature were 5.0%, 7.0 and 25 °C, respectively. A total biomass of 26.4 g/L with a lipid content of 52.2% (corresponding to a lipid yield of 13.8 g/L) was achieved after cultivation of T. fermentans HWZ004 under the above-mentioned conditions for 7 days. The lipid coefficient (lipid yield on substrate consumed) is 17.0, which is much higher than the corresponding one (11.9) obtained on detoxified rice straw hemicullulose hydrolysate by original yeast T. fermentans CICC 1368. The fatty acid composition of the lipid was found to be similar to that of vegetable oil and its unsaturated fatty acid content was over 70%, thus the lipid is a promising material for biodiesel production.