解脂耶氏酵母(Yarrowia lipolytica)可很好地发酵甘油生产赤藓糖醇。NaCl作为渗透压调节剂提升发酵体系渗透压有利于提高赤藓糖醇产量,但高渗会抑制酵母生长,延长发酵周期,降低生产强度。该研究以甘氨酸、脯氨酸为渗透压保护剂,在高渗环境下,研究其如何提升酵母细胞耐高渗能力。结果发现,Y.lipolytica可吸收胞外甘氨酸和脯氨酸并在胞内积累以抵御高渗胁迫,并显著提升高渗环境下的菌体量,促进赤藓糖醇的高效合成。在7 L发酵罐水平,初始渗透压为4.17±0.17 osmol/kg时,发酵初始添加30 mg/L甘氨酸和40 mg/L脯氨酸,发酵时间由108 h减少到90 h,赤藓糖醇最终产量达到了93.6±4.2 g/L,生产强度为1.04±0.05 g/(L·h),产物得率为0.49±0.03 g/g,分别比未添加保护剂时增加了4.12%,25.3%和4.26%。

Yarrowia lipolytica,one of the unconventional yeasts,grows well and produces erythritol with a high formation rate using glycerol as a sole carbon source. High osmotic pressure generated by NaCl and glycerol benefitted to enhance erythritol production,but high osmotic pressure would inhibit yeast cell growth,extend the period of fermentation,and drop the productivity down. In this research,glycine and proline were used as the osmoprotectants to investigate how the hyperosmotic resistance of Y. lipolytica was improved. The results indicated that Y. lipolytica could import extracellular amino acid and accumulate as a compatible solute in cytoplasm in order to resist the damages of the high osmotic pressure. Consequently,the erythritol synthesis and the biomass were enhanced remarkably. In 7 L stirred fermenter test with the 4. 17 ± 0. 17 osmol / kg of initial osmotic pressure,when 30 mg / L glycine and 40 mg / L proline were added at the beginning of the fermentation,the fermentation period was reduced from 108 h to 90 h,and the final concentration,productivity and yield of erythritol were 93. 6 ± 4. 2 g / L,1. 04 ± 0. 05 g /( L· h) and 0. 49 ± 0. 03 g / g,which had increased 4. 12%,25. 3% and 4. 26%,respectively.