Graduate School of Science, Technology and Innovation, Kobe University, 1-1 Rokkodaicho, Nada-ku, Kobe, Hyogo, 657-8501, Japan.
RIKEN Center for Sustainable Resource Science, 1-7-22 Suehiro-cho, Tsurumi-ku, Yokohama, Kanagawa, 230-0045, Japan.
Appl Microbiol Biotechnol. 2019 Feb;103(3):1243-1254. doi: 10.1007/s00253-018-9493-4. Epub 2018 Nov 17.
Glutathione has diverse physiological functions, and therefore, the demand for it has increased recently. Currently, industrial mass production of glutathione is performed from D-glucose via fermentation by the budding yeast Saccharomyces cerevisiae. However, use of D-glucose often competes with demands for various other industries, leading to high production costs. To affordably produce glutathione, we aimed to produce high amounts of glutathione from D-glucose and D-xylose, which are the main constituents of lignocellulosic biomass pre-treated with acids. Genetically engineered S. cerevisiae strains that can produce high amounts of glutathione and assimilate D-xylose were constructed and cultured in media containing D-xylose. Among these recombinant strains, a S. cerevisiae GCI (XR/XDH/XK) strain over-expressing γ-glutamylcysteine synthetase, glutathione synthetase, D-xylose reductase, xylitol dehydrogenase, and xylulokinase genes successfully consumed D-xylose in the medium and produced the highest amount of glutathione. When strains were grown in media containing D-glucose and D-xylose, the GCI (XR/XDH/XK) strain showed 4.6-fold higher volumetric glutathione production (mg/L-broth), 2.2-fold higher glutathione content (%), and 2.1-fold higher cell growth (g-cell/L-broth) than the vector control strain of YPH499 (Vector). Furthermore, when recombinant S. cerevisiae strains were grown in medium containing fermentation inhibitory materials, the GCI (XR/XDH/XK) strain produced 5.8- and higher volumetric glutathione, 2.6-fold higher intracellular glutathione, and 2.9-fold higher cell growth than the vector control YPH499 (Vector) strain. The gradual sugar consumption by recombinant S. cerevisiae strains in medium containing D-glucose and D-xylose leads to high yields of glutathione. These results indicate the potential for glutathione production from lignocellulosic materials.
谷胱甘肽具有多种生理功能，因此最近对其的需求有所增加。目前，工业上大规模生产谷胱甘肽是通过芽殖酵母酿酒酵母从 D-葡萄糖经发酵获得的。然而，D-葡萄糖的使用常常与其他各种行业的需求竞争，导致生产成本高。为了经济地生产谷胱甘肽，我们旨在从经酸预处理的木质纤维素生物质的主要成分 D-葡萄糖和 D-木糖中生产大量的谷胱甘肽。构建并在含有 D-木糖的培养基中培养能够大量生产谷胱甘肽并同化 D-木糖的基因工程酿酒酵母菌株。在这些重组菌株中，一株过表达 γ-谷氨酰半胱氨酸合成酶、谷胱甘肽合成酶、D-木糖还原酶、木糖醇脱氢酶和木酮糖激酶基因的酿酒酵母 GCI（XR/XDH/XK）菌株成功地消耗了培养基中的 D-木糖并产生了最高量的谷胱甘肽。当菌株在含有 D-葡萄糖和 D-木糖的培养基中生长时，GCI（XR/XDH/XK）菌株的比体积谷胱甘肽产量（mg/L-发酵液）、谷胱甘肽含量（%）和细胞生长（g-细胞/L-发酵液）分别比 YPH499（载体）对照菌株高 4.6 倍、2.2 倍和 2.1 倍。此外，当重组酿酒酵母菌株在含有发酵抑制剂的培养基中生长时，GCI（XR/XDH/XK）菌株的比体积谷胱甘肽产量、细胞内谷胱甘肽含量和细胞生长分别比 YPH499（载体）对照菌株高 5.8 倍、2.6 倍和 2.9 倍。重组酿酒酵母菌株在含有 D-葡萄糖和 D-木糖的培养基中逐渐消耗糖，导致谷胱甘肽产量高。这些结果表明从木质纤维素材料生产谷胱甘肽的潜力。
