Oswald Florian, Stoll I Katharina, Zwick Michaela, Herbig Sophia, Sauer Jörg, Boukis Nikolaos, Neumann Anke
Technical Biology, Institute of Process Engineering in Life Sciences, Karlsruhe Institute of Technology, Karlsruhe, Germany.
Institute of Catalysis Research and Technology (IKFT), Karlsruhe Institute of Technology, Eggenstein-Leopoldshafen, Germany.
Front Bioeng Biotechnol. 2018 Feb 12;6:6. doi: 10.3389/fbioe.2018.00006. eCollection 2018.
Low productivities of bioprocesses using gaseous carbon and energy sources are usually caused by the low solubility of those gases (e.g., H and CO). It has been suggested that increasing the partial pressure of those gases will result in higher dissolved concentrations and should, therefore, be helpful to overcome this obstacle. Investigations of the late 1980s with mixtures of hydrogen and carbon monoxide showed inhibitory effects of carbon monoxide partial pressures above 0.8 bar. Avoiding any effects of carbon monoxide, we investigate growth and product formation of at absolute process pressures of 1, 4, and 7 bar in batch stirred tank reactor cultivations with carbon dioxide and hydrogen as sole gaseous carbon and energy source. With increasing process pressure, the product spectrum shifts from mainly acetic acid and ethanol to almost only formic acid at a total system pressure of 7 bar. On the other hand, no significant changes in overall product yield can be observed. By keeping the amount of substance flow rate constant instead of the volumetric gas feed rate when increasing the process pressure, we increased the overall product yield of 7.5 times of what has been previously reported in the literature. After 90 h of cultivation at a total pressure of 7 bar a total of 4 g L of products is produced consisting of 82.7 % formic acid, 15.6 % acetic acid, and 1.7 % ethanol.
使用气态碳源和能源的生物过程生产率较低，通常是由这些气体（如氢气和一氧化碳）的低溶解度所致。有人提出，提高这些气体的分压会导致更高的溶解浓度，因此应有助于克服这一障碍。20世纪80年代后期对氢气和一氧化碳混合物的研究表明，一氧化碳分压高于0.8巴时具有抑制作用。为避免一氧化碳的任何影响，我们在间歇搅拌釜式反应器培养中，以二氧化碳和氢气作为唯一的气态碳源和能源，研究了在1、4和7巴的绝对过程压力下的生长和产物形成情况。随着过程压力的增加，产物谱从主要为乙酸和乙醇转变为在总系统压力为7巴时几乎仅为甲酸。另一方面，未观察到总产物产率有显著变化。在提高过程压力时，通过保持物质流量速率恒定而非体积气体进料速率恒定，我们将总产物产率提高到了文献中先前报道值的7.5倍。在7巴的总压力下培养90小时后，共产生了4克/升的产物，其中包括82.7%的甲酸、15.6%的乙酸和1.7%的乙醇。
