Sauer Michael, Branduardi Paola, Valli Minoska, Porro Danilo
Dipartimento di Biotecnologie e Bioscienze, Università degli Studi di Milano-Bicocca, Piazza della Scienza 2, 20126 Milan, Italy.
Appl Environ Microbiol. 2004 Oct;70(10):6086-91. doi: 10.1128/AEM.70.10.6086-6091.2004.
Yeasts do not possess an endogenous biochemical pathway for the synthesis of vitamin C. However, incubated with l-galactose, L-galactono-1,4-lactone, or L-gulono-1,4-lactone intermediates from the plant or animal pathway leading to l-ascorbic acid, Saccharomyces cerevisiae and Zygosaccharomyces bailii cells accumulate the vitamin intracellularly. Overexpression of the S. cerevisiae enzymes d-arabinose dehydrogenase and D-arabinono-1,4-lactone oxidase enhances this ability significantly. In fact, the respective recombinant yeast strains even gain the capability to accumulate the vitamin in the culture medium. An even better result is obtainable by expression of the plant enzyme L-galactose dehydrogenase from Arabidopsis thaliana. Budding yeast cells overexpressing the endogenous D-arabinono-1,4-lactone oxidase as well as L-galactose dehydrogenase are capable of producing about 100 mg of L-ascorbic acid liter(-1), converting 40% (wt/vol) of the starting compound L-galactose.
酵母没有用于合成维生素C的内源性生化途径。然而，将酿酒酵母和巴氏接合酵母细胞与来自植物或动物途径的导致L-抗坏血酸的L-半乳糖、L-半乳糖-1,4-内酯或L-古洛糖酸-1,4-内酯中间体一起孵育时，细胞会在细胞内积累该维生素。酿酒酵母的D-阿拉伯糖脱氢酶和D-阿拉伯糖-1,4-内酯氧化酶的过表达显著增强了这种能力。事实上，相应的重组酵母菌株甚至获得了在培养基中积累维生素的能力。通过表达来自拟南芥的植物酶L-半乳糖脱氢酶可获得更好的结果。过表达内源性D-阿拉伯糖-1,4-内酯氧化酶以及L-半乳糖脱氢酶的芽殖酵母细胞能够产生约100毫克/升的L-抗坏血酸，将起始化合物L-半乳糖的40%（重量/体积）进行了转化。
