Anaerobic fermentation of organic wastes using microbial mixed cultures is a promising avenue to treat residues and obtain added-value products. However, the process has some important limitations that prevented so far any industrial application. One of the main issues is that we are not able to predict reliably the product spectrum (i.e. the stoichiometry of the process) because the complex microbial community behaviour is not completely understood. To address this issue, in this work we propose a new metabolic network of glucose fermentation by microbial mixed cultures that incorporates electron bifurcation and homoacetogenesis. Our methodology uses NADH balances to analyse published experimental data and evaluate the new stoichiometry proposed. Our results prove for the first time the inclusion of electron bifurcation in the metabolic network as a better description of the experimental results. Homoacetogenesis has been used to explain the discrepancies between observed and theoretically predicted yields of gaseous H₂ and CO₂ and it appears as the best solution among other options studied. Overall, this work supports the consideration of electron bifurcation as an important biochemical mechanism in microbial mixed cultures fermentations and underlines the importance of considering homoacetogenesis when analysing anaerobic fermentations.

使用微生物混合培养物对有机废物进行厌氧发酵是一种处理残留物并获得增值产品的有前途的途径。但是，该方法具有一些重要的局限性，至今仍无法进行任何工业应用。主要问题之一是我们无法可靠地预测产品范围（即过程的化学计量），因为尚未完全了解复杂的微生物群落行为。为了解决这个问题，在这项工作中，我们提出了一种新的通过微生物混合培养的葡萄糖发酵的代谢网络，该网络结合了电子分叉和同型产乙酸。我们的方法使用NADH天平来分析已发布的实验数据并评估建议的新化学计量。我们的结果首次证明了在代谢网络中包含电子分叉，可以更好地描述实验结果。均相产乙酸已被用来解释气态H的观测产量与理论预测产量之间的差异₂和CO ₂，它似乎是研究的其他选择中的最佳解决方案。总的来说，这项工作支持了将电子分叉作为微生物混合培养发酵中重要的生化机制的考虑，并强调了在分析厌氧发酵时考虑均乙酸的重要性。