玉米芯残渣原料发酵微生物油脂的营养因子优化

Culture Optimization of Lipid Fermentation by Trichosporon cutaneum Using Corncob Residue

玉米芯残渣是生产木糖后剩下的固体废弃物,也是一种高纤维素含量的生物质.为有效利用玉米芯残渣生产微生物油脂,对适于在玉米芯水解液中进行发酵的产油微生物进行了筛选,对水解液中添加的营养物质进行了优化,最后通过改变纤维素酶用量来提高水解液中的糖浓度以提高酵母的油脂产量.结果发现皮状丝孢酵母Trichosporon cutaneum 20271能够在水解液中进行油脂发酵;玉米浆(CSL)能显著提高酵母在水解液中的发酵速率,同时营养物不改变酵母的脂肪酸组分;利用纤维素酶用量为15 FPU/g DM得到的水解液进行油脂发酵时,酵母干重达到38.4 g/L,酵母的油脂产量达到12.3 g/L,油脂产率提高到0.064 g L-1 h-1,酵母含油率为32.1%.研究表明,皮状丝孢酵母T.cutaneum20271能够利用玉米芯残渣水解液进行油脂发酵,水解液经优化得到了较好的油脂发酵结果,本研究为微生物油脂发酵提供了廉价的原料,并为利用玉米芯残渣水解液生产油脂提供了切实可行的发酵方法.

Corncob residue, solid waste after the xylose production from hemicellulose with high cellulose content, can be directly hydrolyzed by cellulase to produce microbial lipid. To produce microbial lipid efficiently, five oleaginous yeasts were tested to screen the most optimal strain for lipid fermentation in the corncob residue hydrolysate. Then the nutrients in the hydrolysate were optimized and finally the lipid production was improved by increasing sugar concentration of the hydrolysate through changing cellulase amount. Trichosporon cutaneum 20271 could grow and produce microbial lipid in the corncob residue hydrolysate; and corn steep liquor （CSL） could significantly improve the lipid production. In addition, different nutrient did not influence the fatty acid composition. At last, the highest dry cell weight （DCW）, lipid titer, lipid content and lipid productivity of 38.4 g/L, 12.3 g/L, 32.1% and 0.064 g L-1 h-1 were obtained respectively when cellulase dose was 15 FPU/g DM. We also found that T. cutaneum 20271 could produce microbial lipid with corncob residue hydrolydate, and that the lipid fermentation performance was improved by optimizing the hydrolysate medium. This study provided not only an economical feedstock option to produce microbial lipid, but also a practical method for CCR utilization.