Functional sugar alcohols have been widely used in the food, medicine, and pharmaceutical industries for their unique properties. Among these, erythritol is a zero calories sweetener produced by the yeast Yarrowia lipolytica. However, in wild-type strains, erythritol is produced with low productivity and yield and only under high osmotic pressure together with other undesired polyols, such as mannitol or d-arabitol. The yeast is also able to catabolize erythritol in non-stressing conditions. Herein, Y. lipolytica has been metabolically engineered to increase erythritol production titer, yield, and productivity from glucose. This consisted of the disruption of anabolic pathways for mannitol and d-arabitol together with the erythritol catabolic pathway. Genes ZWF1 and GND encoding, respectively, glucose-6-phosphate dehydrogenase and 6-phosphogluconate dehydrogenase were also constitutively expressed in regenerating the NADPH2 consumed during erythritol synthesis. Finally, the gene RSP5 gene from Saccharomyces cerevisiae encoding ubiquitin ligase was overexpressed to improve cell thermoresistance. The resulting strain HCY118 is impaired in mannitol or d-arabitol production and erythritol consumption. It can grow well up to 35 °C and retain an efficient erythritol production capacity at 33 °C. The yield, production, and productivity reached 0.63 g/g, 190 g/L, and 1.97 g/L·h in 2-L flasks, and increased to 0.65 g/g, 196 g/L, and 2.51 g/L·h in 30-m3 fermentor, respectively, which has economical practical importance. The strategy developed herein yielded an engineered Y. lipolytica strain with enhanced thermoresistance and NADPH supply, resulting in a higher ability to produce erythritol, but not mannitol or d-arabitol from glucose. This is of interest for process development since it will reduce the cost of bioreactor cooling and erythritol purification.

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解脂耶氏酵母的代谢工程用于耐热性和提高赤藓糖醇的生产力

功能性糖醇因其独特的性能已广泛应用于食品、医药和制药行业。其中，赤藓糖醇是一种由酵母解脂耶氏酵母生产的零卡路里甜味剂。然而，在野生型菌株中，赤藓糖醇的生产效率和产量很低，并且只能在高渗透压下与其他不希望的多元醇（例如甘露醇或 d-阿拉伯糖醇）一起生产。酵母还能够在非应激条件下分解代谢赤藓糖醇。在此，解脂耶氏酵母经过代谢工程改造，可提高赤藓糖醇的生产效价、产率和葡萄糖产率。这包括破坏甘露醇和 d-阿拉伯糖醇的合成代谢途径以及赤藓糖醇分解代谢途径。基因 ZWF1 和 GND 分别编码，葡萄糖-6-磷酸脱氢酶和 6-磷酸葡萄糖酸脱氢酶也在赤藓糖醇合成过程中消耗的 NADPH2 再生过程中组成型表达。最后，来自酿酒酵母的基因 RSP5 基因编码泛素连接酶被过表达以提高细胞耐热性。由此产生的 HCY118 菌株在甘露醇或 d-阿拉伯糖醇的产生和赤藓糖醇的消耗方面受到损害。它可以在高达 35°C 的温度下很好地生长，并在 33°C 时保持高效的赤藓糖醇生产能力。产率、产量和生产率在 2-L 烧瓶中分别达到 0.63 g/g、190 g/L 和 1.97 g/L·h，并提高到 0.65 g/g、196 g/L 和 2.51 g/L·h h 分别在 30-m3 发酵罐中，这在经济上具有实际意义。本文开发的策略产生了具有增强的耐热性和 NADPH 供应的工程化解脂耶氏酵母菌株，导致更高的能力从葡萄糖生产赤藓糖醇，但不是甘露糖醇或 d-阿拉伯糖醇。这对工艺开发很有意义，因为它将降低生物反应器冷却和赤藓糖醇纯化的成本。