Burger Yvonne, Schwarz Fabian M, Müller Volker
Department of Molecular Microbiology and Bioenergetics, Institute of Molecular Biosciences, Johann Wolfgang Goethe University, Max-von-Laue-Str. 9, 60438, Frankfurt, Germany.
Biotechnol Biofuels Bioprod. 2022 May 11;15(1):48. doi: 10.1186/s13068-022-02147-5.
In times of global warming there is an urgent need to replace fossil fuel-based energy vectors by less carbon dioxide (CO)-emitting alternatives. One attractive option is the use of molecular hydrogen (H) since its combustion emits water (HO) and not CO. Therefore, H is regarded as a non-polluting fuel. The ways to produce H can be diverse, but steam reformation of conventional fossil fuel sources is still the main producer of H gas up to date. Biohydrogen production via microbes could be an alternative, environmentally friendly and renewable way of future H production, especially when the flexible and inexpensive C1 compound formate is used as substrate.
In this study, the versatile compound formate was used as substrate to drive H production by whole cells of the thermophilic acetogenic bacterium Thermoanaerobacter kivui which harbors a highly active hydrogen-dependent CO reductase (HDCR) to oxidize formate to H and CO and vice versa. Under optimized reaction conditions, T. kivui cells demonstrated the highest H production rates (qH = 685 mmol g h) which were so far reported in the literature for wild-type organisms. Additionally, high yields (Y) of 0.86 mol mol and a hydrogen evolution rate (HER) of 999 mmol L h were observed. Finally, stirred-tank bioreactor experiments demonstrated the upscaling feasibility of the applied whole cell system and indicated the importance of pH control for the reaction of formate-driven H production.
The thermophilic acetogenic bacterium T. kivui is an efficient biocatalyst for the oxidation of formate to H (and CO). The existing genetic tool box of acetogenic bacteria bears further potential to optimize biohydrogen production in future and to contribute to a future sustainable formate/H bio-economy.
在全球变暖的时代，迫切需要用二氧化碳（CO）排放量更低的替代能源来取代基于化石燃料的能源载体。一个有吸引力的选择是使用分子氢（H），因为其燃烧产生水（H₂O）而不是CO。因此，H被视为一种无污染燃料。生产H的方式多种多样，但传统化石燃料源的蒸汽重整至今仍是H₂气体的主要生产方式。通过微生物生产生物氢可能是未来生产H的一种替代的、环境友好且可再生的方式，特别是当使用灵活且廉价的C1化合物甲酸盐作为底物时。
在本研究中，通用化合物甲酸盐被用作底物，以驱动嗜热产乙酸细菌基维嗜热厌氧杆菌（Thermoanaerobacter kivui）的全细胞产生H₂。该细菌含有一种高活性的氢依赖性CO还原酶（HDCR），可将甲酸盐氧化为H₂和CO，反之亦然。在优化的反应条件下，基维嗜热厌氧杆菌细胞表现出迄今为止文献中报道的野生型生物的最高H₂产率（qH₂ = 685 mmol g⁻¹ h⁻¹）。此外，还观察到高产率（Y）为0.86 mol mol⁻¹以及析氢速率（HER）为999 mmol L⁻¹ h⁻¹。最后，搅拌罐生物反应器实验证明了所应用的全细胞系统的放大可行性，并表明pH控制对甲酸盐驱动的H₂生产反应的重要性。
嗜热产乙酸细菌基维嗜热厌氧杆菌是将甲酸盐氧化为H₂（和CO）的高效生物催化剂。产乙酸细菌现有的遗传工具盒在未来优化生物氢生产以及为未来可持续的甲酸盐/H₂生物经济做出贡献方面具有进一步的潜力。
