School of Food and Advanced Technology, Massey University, Private Bag 11-222, Palmerston North, New Zealand.
Riddet Institute, Massey University, Private Bag 11222, Palmerston North, 4442, New Zealand.
Bioprocess Biosyst Eng. 2020 May;43(5):885-894. doi: 10.1007/s00449-020-02285-w. Epub 2020 Jan 25.
The bacterial production of acetate via reductive acetogenesis along the Wood-Ljungdahl metabolic pathway is an important source of this molecule in several environments, ranging from industrial bioreactors to the human gastrointestinal tract. Here, we contributed to the study of reductive acetogens by considering mathematical modelling techniques for the prediction of bacterial growth and acetate production. We found that the incorporation of a hydrogen uptake concentration threshold into the models improves their predictions and we calculated this threshold as 86.2 mM (95% confidence interval 6.1-132.6 mM). Monod kinetics and first-order kinetics models, with the inclusion of two candidate threshold terms or reversible Michaelis-Menten kinetics, were compared to experimental data and the optimal formulation for predicting both growth and metabolism was found. The models were then used to compare the efficacy of two growth media for acetogens. We found that the recently described general acetogen medium was superior to the DSMZ medium in terms of unbiased estimation of acetogen growth and investigated the contribution of yeast extract concentration to acetate production and bacterial growth in culture. The models and their predictions will be useful to those studying both industrially and environmentally relevant reductive acetogenesis and allow for straightforward adaptation to similar cases with different organisms.
通过 Wood-Ljungdahl 代谢途径的还原性乙酰生成作用，细菌可以生产乙酸盐，这是该分子在多种环境中的一个重要来源，从工业生物反应器到人类胃肠道。在这里，我们通过考虑用于预测细菌生长和乙酸盐生产的数学建模技术，为还原性乙酰生成菌的研究做出了贡献。我们发现，将氢气摄取浓度阈值纳入模型可以提高其预测能力，我们计算出该阈值为 86.2 mM（置信区间为 6.1-132.6 mM）。我们比较了包含两个候选阈值项或可逆米氏动力学的 Monod 动力学和一级动力学模型与实验数据，并找到了最佳的预测生长和代谢的公式。然后，我们使用这些模型比较了两种适合乙酰生成菌生长的培养基的效果。我们发现，与 DSMZ 培养基相比，最近描述的通用乙酰生成菌培养基在对乙酰生成菌生长进行无偏估计方面更具优势，并研究了酵母提取物浓度对培养物中乙酸盐生产和细菌生长的贡献。这些模型及其预测结果将对研究工业和环境相关还原性乙酰生成的人有用，并允许针对具有不同生物体的类似情况进行简单的适应性调整。
