The impact of the four membrane-bound [NiFe]-hydrogenases (Hyd) of Escherichia coli on total H₂-oxidizing activity during fermentation of a mixture of glucose, glycerol and formate at different pHs was examined. It was shown that Hyd-2 had a major contribution to total Hyd activity at pH 7.5 in early-stationary phase (24 h) cells, while the main contribution was made by Hyd-3 in late-stationary phase (72 h). Hyd-4-dependent Hyd activity could be demonstrated at pH 6.5 in cells lacking Hyd-1, Hyd-2 and Hyd-3. at pH 7.5 Hyd-4-dependent formate dehydrogenase (FDH-H) activity was demonstrated. Growth properties and fermentation end product patterns during 72 h demonstrated that the cells retained viability deep into stationary phase. Our findings emphasize the importance of formate in modulating H₂ metabolism, presumably by contributing to maintain redox, pH and pmf balance. This is important for regulating and enhancing H₂ production when a mixture of carbon sources is applied.

大肠杆菌的四种膜结合[NiFe]-加氢酶（Hyd）对总H _2的影响检查了葡萄糖，甘油和甲酸混合物在不同pH下发酵过程中的氧化活性。研究表明，Hyd-2对早期静止期（24小时）细胞在pH 7.5时的总Hyd活性有主要贡献，而主要贡献是由Hyd-3在静止后期（72 h）产生。在缺乏Hyd-1，Hyd-2和Hyd-3的细胞中，Hyd-4依赖性Hyd活性可在pH 6.5时证明。在pH 7.5时，证明了Hyd-4依赖性甲酸脱氢酶（FDH-H）的活性。72小时内的生长特性和发酵终产物模式表明，细胞在稳态之前一直保持活力。我们的发现强调了甲酸盐在调节H ₂代谢中的重要性，大概是通过维持氧化还原，pH和pmf来进行的。平衡。当应用碳源混合物时，这对于调节和提高H _2的生产非常重要。