Xylose isomerase (XI) pathway has been widely employed to enable to convert xylose and glucose into commercially feasible lignocellulosic ethanol products. Nevertheless, studies about the effect of different promoters to the expression of A are lacking. Therefore, five strains with , , , , promoters were constructed. Among them, INV/pHM368-P-A generated with A driven by 1 promoter displayed the highest xylose utilization rate (approximately 19.98 %) using xylose as the only carbon source. With 4 g/L glucose and 10 g/L xylose as the carbon sources, the xylose utilization rate was 60.04 %. Moreover, the utilization rate increased to 64.04 % with fermentation temperature elevated from 28 °C to 30 °C and reached 83.09 % with peptone and yeast extract as the nitrogen sources. The ethanol titer reached 1.74 g/L with a yield of 0.38 g/g sugar under this condition. In Comparison with direct fermentation, the single cell protein (SCP) was 1.27-fold higher during aerobic fed-batch fermentation. Furthermore, INV/pHM368-P-A attains high ethanol productivities and yields by converting glucose and xylose from non-detoxified bagasse hydrolysates as carbon sources. The results extend our understanding of the xylose metabolism of and provide a platform for biomass conversion to ethanol and SCP, hence paving the way for the development of a more economical and sustainable approach to co-fermentation performance and capabilities for future engineering.

中文翻译：

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改造酿酒酵母的木糖代谢以进行乙醇和单细胞蛋白质生物转化


木糖异构酶 (XI) 途径已被广泛应用于将木糖和葡萄糖转化为商业上可行的木质纤维素乙醇产品。然而，目前缺乏关于不同启动子对A表达影响的研究。因此，构建了五个带有 、 、 、 、 启动子的菌株。其中，以木糖为唯一碳源，由1个启动子驱动的A产生的INV/pHM368-PA显示出最高的木糖利用率（约19.98%）。以4 g/L葡萄糖和10 g/L木糖为碳源时,木糖利用率为60.04%。而且，当发酵温度从28℃升高到30℃时，利用率提高到64.04%，以蛋白胨和酵母抽提物为氮源时，利用率达到83.09%。在此条件下乙醇滴度达到1.74 g/L，糖得率为0.38 g/g。与直接发酵相比，有氧补料分批发酵的单细胞蛋白（SCP）高出1.27倍。此外，INV/pHM368-PA 通过将未解毒的甘蔗渣水解产物中的葡萄糖和木糖转化为碳源，获得了高乙醇生产率和产量。这些结果扩展了我们对木糖代谢的理解，并为生物质转化为乙醇和SCP提供了平台，从而为未来工程开发更经济、更可持续的共发酵性能和能力的方法铺平了道路。