Effective utilization of glucose, xylose, and acetate, common carbon sources in lignocellulose hydrolysate, can boost biomanufacturing economics. However, carbon leaks into biomass biosynthesis pathways instead of the intended target product remain to be optimized. This study aimed to enhance α-carotene production by optimizing glucose, xylose, and acetate utilization in a high-efficiency cell factory. Heterologous xylose pathway expression in resulted in strain m4, exhibiting a two-fold increase in α-carotene production from xylose compared to glucose. Xylose utilization was found to boost the biosynthesis of pyruvate and acetyl-CoA, essential precursors for carotenoid biosynthesis. Additionally, metabolic engineering including , and deletion, completely disrupted the metabolic connection between glycolysis and the TCA cycle, further enhancing α-carotene production. This strategic intervention directed glucose and xylose primarily towards target chemical production, while acetate supplied essential metabolites for cell growth recovery. The engineered strain m8 achieved 30 mg/g α-carotene, 67% higher than strain m4. In fed-batch fermentation, strain m8 produced 1802 mg/L of α-carotene, marking the highest titer reported to date in microbial fermentation. Moreover, it exhibited excellent performance in authentic lignocellulosic hydrolysate, producing 216 mg/L α-carotene, 1.45 times higher than the initial strain (m4). These labor-division strategies significantly contribute to the development of clean processes for producing various valuable chemicals from lignocellulosic resources.

中文翻译：

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谷氨酸棒杆菌高效生产α-胡萝卜素的工程碳源分工


有效利用葡萄糖、木糖和乙酸盐（木质纤维素水解产物中的常见碳源）可以提高生物制造的经济效益。然而，碳泄漏到生物质生物合成途径而不是预期的目标产品仍有待优化。本研究旨在通过优化高效细胞工厂中葡萄糖、木糖和乙酸盐的利用来提高 α-胡萝卜素的产量。异源木糖途径表达产生了菌株 m4，与葡萄糖相比，木糖产生的 α-胡萝卜素产量增加了两倍。研究发现，木糖的利用可以促进丙酮酸和乙酰辅酶A的生物合成，而丙酮酸和乙酰辅酶A是类胡萝卜素生物合成的重要前体。此外，包括 、 和缺失在内的代谢工程完全破坏了糖酵解和 TCA 循环之间的代谢联系，进一步增强了 α-胡萝卜素的产生。这种战略干预主要将葡萄糖和木糖引导至目标化学品生产，而乙酸盐则为细胞生长恢复提供必需的代谢物。工程菌株 m8 的 α-胡萝卜素含量为 30 mg/g，比菌株 m4 高 67%。在补料分批发酵中，菌株m8产生了1802 mg/L的α-胡萝卜素，这是迄今为止报道的微生物发酵的最高滴度。此外，它在纯木质纤维素水解产物中表现出优异的性能，产生216 mg/L α-胡萝卜素，是初始菌株（m4）的1.45倍。这些分工策略极大地促进了从木质纤维素资源生产各种有价值化学品的清洁工艺的发展。