Department of Chemistry, University of Science & Technology of China, Hefei, China.
Biotechnol Bioeng. 2011 Feb;108(2):345-53. doi: 10.1002/bit.22908.
Homoacetogenesis is an important potential hydrogen sink in acetogenesis, in which hydrogen is used to reduce carbon dioxide to acetate. So far the acetate production from homoacetogenesis, especially its kinetics, has not been given sufficient attention. In this work, enhanced production of acetate from anaerobic conversion of glucose through coupling glucose fermentation and homoacetogenesis is investigated with both experimental and mathematical approaches. Experiments are conducted to explore elevated acetate production in a coupled anaerobic system. Acetate production could be achieved by homoacetogenesis with a relative high acetate yield under mixed fermentation conditions. With the experimental observations, a kinetic model is formulated to describe such a homoacetogenic process. The maximum homoacetogenic rate (k(m,homo)) is estimated to be 28.5 ± 1.7 kg COD kg⁻¹ COD day⁻¹ with an uptake affinity constant of 3.7 × 10⁻⁵± 3.1 × 10⁻⁶kg COD m⁻³. The improved calculation of homoacetogenic kinetics by our approach could correct the underestimation of homoacetogenesis in anaerobic fermentation processes, as it often occurs in these systems supported by literature analysis. The model predictions match the experimental results in different cases well and provide insights into the dynamics of anaerobic glucose conversion and acetate production. Furthermore, acetate production via homoacetogenesis increases by about 40% through utilizing the fed-batch coupling system, attributed to a balance between the hydrogen production in the acetogenesis phase and the hydrogen consumption in the homoacetogenesis phase. This work provides an effective way for increased anaerobic acetate production, and gives us a better understanding about the homoacetogenic kinetics in the anaerobic fermentation process.
同型产乙酸作用是产乙酸作用中一个重要的潜在氢汇，其中氢被用来将二氧化碳还原为乙酸。到目前为止，同型产乙酸作用，特别是其动力学，还没有得到足够的重视。在这项工作中，通过实验和数学方法研究了通过葡萄糖厌氧转化偶联葡萄糖发酵和同型产乙酸作用来增强乙酸的生产。进行了实验以探索在耦合厌氧系统中提高乙酸的生产。在混合发酵条件下，同型产乙酸作用可以实现相对较高的乙酸产率。通过实验观察，建立了一个动力学模型来描述这种同型产乙酸过程。最大同型产乙酸速率（k(m,homo)）估计为 28.5±1.7kg COD kg⁻¹ COD day⁻¹，摄取亲和力常数为 3.7×10⁻⁵±3.1×10⁻⁶kg COD m⁻³。通过我们的方法对同型产乙酸动力学进行改进的计算，可以纠正厌氧发酵过程中同型产乙酸作用的低估，因为在文献分析支持的这些系统中经常会出现这种情况。模型预测与不同情况下的实验结果吻合良好，为厌氧葡萄糖转化和乙酸生产动力学提供了深入的了解。此外，通过利用 fed-batch 偶联系统，同型产乙酸作用可使乙酸的产量增加约 40%，这归因于产乙酸阶段的氢气产生和同型产乙酸阶段的氢气消耗之间的平衡。这项工作为提高厌氧乙酸生产提供了一种有效的方法，并使我们对厌氧发酵过程中的同型产乙酸动力学有了更好的理解。
