酿酒酵母产苹果酸的还原TCA路径构建及发酵调控

Construction and fermentation control of reductive TCA pathway for malic acid production in Saccharomyces cerevisiae

摘要:

苹果酸广泛应用于食品、化工行业。文中通过在酿酒酵母内敲除丙酮酸脱羧酶PDC1，并通过构建胞质内还原TCA的路径，即超表达丙酮酸羧化酶和苹果酸脱氢酶，成功地实现了苹果酸的生产。在野生型菌株中基本检测不到苹果酸的生成，而在工程菌株，苹果酸发酵浓度达到了45 mmol /L，同时副产物乙醇的产量也降低了18%。进一步通过发酵调控提高第二信使Ca2+的浓度使苹果酸的产量提高了7 %，在此基础上提高丙酮酸羧化酶的辅酶生物素浓度，使苹果酸的产量达到52.5 mmol /L，较原始菌株提高了16%。

Abstract:

Malic acid is widely used in food, and chemical industries. Through overexpressing pyruvate carboxylase and malate dehydrogenase in pdc1-deficient Saccharomyces cerevisiae, malic acid was successfully produced through the reductive TCA pathway. No malic acid was detected in wild type Saccharomyces cerevisiae, however, 45 mmol/L malic acid was produced in engineered strain, and the concentration of byproduct ethanol also reduced by 18%. The production of malic acid enhanced 6% by increasing the concentration of Ca2+. In addition, the final concentration reached 52.5 mmol /L malic acid by addition of biotin. The increasing is almost 16% higher than that of the original strain.