Crude glycerol as a promising feedstock for microbial lipid production contains several impurities that make it toxic stress inducer at high amount. Under stress conditions, microorganisms can accumulate l-proline as a safeguard. Herein, l-proline was assessed as an anti-stress agent in crude glycerol media. Crude glycerol was converted to microbial lipids by the oleaginous yeast Rhodosporidium toruloides CGMCC 2.1389 in a two-staged culture mode. The media was supplied with exogenous l-proline to improve lipid production efficiency in high crude glycerol stress. An optimal amount of 0.5 g/L l-proline increased lipid titer and lipid yield by 34% and 28%, respectively. The lipid titer of 12.2 g/L and lipid content of 64.5% with a highest lipid yield of 0.26 g/g were achieved with l-proline addition, which were far higher than those of the control, i.e., lipid titer of 9.1 g/L, lipid content of 58% and lipid yield of 0.21 g/g. Similarly, l-proline also improved cell growth and glycerol consumption. Moreover, fatty acid compositional profiles of the lipid products was found suitable as a potential feedstock for biodiesel production. Our study suggested that exogenous l-proline improved cell growth and lipid production on crude glycerol by R. toruloides. The fact that higher lipid yield as well as glycerol consumption indicated that l-proline might act as a potential anti-stress agent for the oleaginous yeast strain.

中文翻译：

---

外源 L-脯氨酸提高了圆红冬孢酵母粗甘油的脂质产量。


粗甘油作为微生物脂质生产的有前途的原料含有多种杂质，使其在大量时成为有毒应激诱导剂。在应激条件下，微生物可以积累 L-脯氨酸作为保护措施。在此，评估了 L-脯氨酸在粗甘油培养基中作为抗应激剂的作用。产油酵母圆红冬孢酵母 CGMCC 2.1389 在两阶段培养模式下将粗甘油转化为微生物脂质。向培养基提供外源L-脯氨酸以提高高粗甘油胁迫下的脂质生产效率。 0.5 g/L L-脯氨酸的最佳用量可使脂质滴度和脂质产量分别增加 34% 和 28%。添加L-脯氨酸后，脂质滴度为12.2 g/L，脂质含量为64.5%，脂质得率最高为0.26 g/g，远高于对照脂质滴度9.1 g/g。 L，脂质含量为58％，脂质产量为0.21g/g。同样，L-脯氨酸还可以改善细胞生长和甘油消耗。此外，发现脂质产品的脂肪酸组成特征适合作为生物柴油生产的潜在原料。我们的研究表明，外源 L-脯氨酸改善了 R. toruloides 粗甘油的细胞生长和脂质生产。较高的脂质产量和甘油消耗量表明 L-脯氨酸可能作为产油酵母菌株的潜在抗应激剂。