To successfully scale-up the production of bio-based building blocks through CO2 and H2-based gas fermentation, it is crucial to deeply understand and control the microbial catalyst response to the bioreactor environment. This study investigates the effects of key process parameters, such as CO2 and H2 partial pressures, gas feeding strategies, and mixture composition, on the production pathways of an evolved Clostridium carboxidivorans strain. The ultimate goal is to optimize 1-hexanol production in elevated-pressure stirred-tank reactors. Continuous gas feeding enhanced acetogenic and solventogenic metabolisms, while gas-limited conditions promoted chain elongation to caproic acid. An optimized process, combining an initial gas-limited step followed by a continuous gas phase, increased 1-hexanol production, achieving a maximum biomass-specific productivity of 0.9 g gCDW−1 day−1. In-situ product extraction improved 1-hexanol carbon selectivity to an unprecedented 60 %. These findings demonstrate the potential of CO2 and H2-fed fermentation to produce high-value chemicals other than ethanol and acetate.

中文翻译：

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利用适应性的卡博西迪沃链菌菌株在高压搅拌罐式反应器中从二氧化碳和氢气中释放己醇


为了通过基于 CO2 和 H2 的气体发酵成功扩大生物基结构单元的生产，深入了解和控制微生物催化剂对生物反应器环境的反应至关重要。本研究调查了关键工艺参数（如 CO2 和 H2 分压、气体进料策略和混合物成分）对进化的卡布二沃拉梭菌菌株生产途径的影响。最终目标是优化高压搅拌罐式反应器中的 1-己醇生产。连续供气增强了乙酸和溶溶剂代谢，而气体限制条件促进了己酸的链伸长。一种优化的工艺，结合了初始气体限制步骤和连续气相，增加了 1-己醇的产量，实现了 0.9 g gCDW-1 天-1 的最大生物质比生产率。原位产物提取将 1-己醇碳选择性提高到前所未有的 60%。这些发现证明了 CO2 和 H2 喂养发酵的潜力，可以生产乙醇和乙酸盐以外的高价值化学品。