Increasing biological hydrogen production

氢被广泛认为是未来的潜在燃料，在世界范围内进行了大量的研究和开发，包括示范汽车和公共汽车运输系统的生产。然而，缺乏一种实用的可再生制氢方法。生物制氢有望成为一种可持续的制氢方法，因为各种废物或木质纤维素底物可以转化为氢气，从而潜在地产生能量并同时进行废物处理。光合细菌长期以来一直被研究其光发酵产氢能力，并已作为模式生物研究光合作用，固氮和生物技术转化。 利用紫色非硫光合细菌Rhodobacter capsulatus，我们最近已经证明了生物制氢的一些改进。在目前的工作中，氢的速率和产量将使用两种方法来提高;生物反应器技术的发展，使用氧化还原状态来控制氧水平，以实现最大的底物转化，和代谢工程，以增加代谢通量在所需的方向。代谢工程，通过引入遗传变化来改变细胞的代谢方式，将用于增加氢生产的能量流和提高光合效率。为了做出这些改变，将为这种生物体建立用于创建多个无标记突变的遗传工具，这也可能对其他对生产其他有用化合物感兴趣的研究人员有用。这个相同的系统将被用于通过新描述的微需氧途径来扩展氢气生产的限制。突变体将在将代谢通量从氢产生（例如乙酸盐形成）转移的途径中产生，并在氧化还原状态下进行测试，其中呼吸速率和因此的氧化还原水平通过氧的受控添加来调节。 通过生理操纵和代谢工程增加氢气产量不仅可能提供从各种废物中可持续制氢的实用方法，而且还可以为可持续生产各种其他有用的化学品和化学产品铺平道路。

Hydrogen is widely considered as a potential fuel of the future with a large amount of research and development world-wide, including the production of demonstration cars and bus transportation systems. However, a practical renewable means of hydrogen production is lacking. Biological hydrogen production holds promise as a sustainable process for hydrogen production since various waste products or lignocellulosic substrates could be converted to hydrogen, thus potentially producing energy and carrying out waste treatment at the same time. The photosynthetic bacteria have long been studied for their photofermentative hydrogen evolution capacity and have served as model organisms for research on photosynthesis, nitrogen fixation, and biotechnological conversions.      Using the purple non-sulfur photosynthetic bacterium Rhodobacter capsulatus we have recently demonstrated a number of improvements in biolgocial hydrogen production. In the present work, rates and yields of hydrogen will be improved using two approaches; development of bioreactor technology using a redox stat to control the oxygen levels for achieving maximum substrate conversion, and metabolic engineering to increase metabolic flux in the desired direction. Metabolic engineering, changing how the metabolism of the cell is used by introducing genetic changes, will be used to increase the flow of energy to hydrogen production and to increase photosynthetic efficiency. In order to make these changes, genetic tools for the creation of multiple markerless mutations will be established for this organism which could also be useful for other researchers interested in the production of other useful compounds. This same system will be used to extend the limits of hydrogen production by the newly described microaerobic pathway. Mutants will be created in pathways that divert metabolic flux away from hydrogen production, such as acetate formation, and tested in a redox stat where the respiratory rate and hence redox level are regulated by the controlled addition of oxygen.      Increasing hydrogen production through both physiological manipulation and metabolic engineering will not only potentially provide a practical means of sustainable hydrogen generation from various waste materials, but could also pave the way for the sustainable production of a variety of other useful chemicals and chemical products.