To enhance the glucaric acid (GA) production in Saccharomyces cerevisiae, the Vitreoscilla hemoglobin was employed to reinforce cellular oxygen supplement. Additionally, the pH-free fermentation strategy was engaged to lower the cost brought by base feeding during the acid-accumulated and long-period glucaric acid production. Recombinant yeast Bga-4 was constructed harboring Vitreoscilla hemoglobin on the basis of previous Bga-3. Higher glucose uptake rate, growth rate, and ethanol reuse rate were achieved in Bga-4 in shake-flask fermentation than those in Bga-3. Furthermore, the fed-batch fermentation in a 5-L bioreactor was performed without pH control, resulting in a final glucaric acid titer of 6.38 g/L. Both the GA titer and biomass were enhanced along with the efficiency of ethanol re-utilization in the presence of VHb. Moreover, the absence of base feeding for long-period fermentation reduced production cost, which is meaningful for industrial applications.

中文翻译：

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通过表达玻璃体血红蛋白提高酿酒酵母中葡萄糖酸的产生

为了提高酿酒酵母中葡糖二酸 (GA) 的产量，采用玻璃体血红蛋白来加强细胞氧补充。此外，采用无 pH 发酵策略以降低在积累酸和长周期葡糖二酸生产过程中碱加料带来的成本。重组酵母 Bga-4 是在先前 Bga-3 的基础上构建的，含有玻璃体血红蛋白。Bga-4 在摇瓶发酵中的葡萄糖摄取率、生长率和乙醇再利用率高于 Bga-3。此外，在 5-L 生物反应器中进行补料分批发酵时没有控制 pH 值，导致最终的葡糖二酸滴度为 6.38 g/L。在 VHb 的存在下，GA 滴度和生物量以及乙醇再利用的效率都得到了提高。而且，