Advancing Biotechnologies for Fuel Generation: Exploiting Transmembrane Cytochromes for Solar Energy Conversion

有关化石燃料储量减少和对燃料安全的担忧的报道经常成为新闻头条。不断上涨的燃料成本每天都在提醒我们，能源需求不断增长的全球社会所面临的挑战。在这种情况下，我们可能会感到惊讶的是，我们可以获得的许多可再生能源，即阳光、风和海浪，在很大程度上仍然是未开发的资源。这主要是由于将这些能量形式转化为燃料存在的挑战，当我们想要玩电脑游戏，开车等等时，能量可以“按需”释放。然而，在植物光合作用过程中，燃料是由阳光中的能量自然产生的。被绿色叶绿素色素吸收的光产生一个带电的电子，这个电子沿着金属中心链被引导到制造糖的催化剂上。这些糖在消化食物后释放能量，为我们和所有动物提供能量。然而，使用种植的植物生产生物燃料是有争议的，因为农业也需要养活世界。因此，在自然过程的启发下，我们建议建立一个人工光合作用系统。从本质上讲，我们希望在微生物上放置微型太阳能板，以便利用阳光来驱动氢的生产——氢是一种燃料，按需释放能量的技术非常先进。我们将使用染料和半导体颗粒作为机械和化学坚固的材料来捕获阳光中的能量并产生带电电子。我们将把这些粒子连接到生物学版的导线上。这些导线是由血红素蛋白构成的，这些血红素蛋白跨越膜，为分隔充满水的腔室（即细菌内部）提供了自然的解决方案。血红素导线是由“岩石呼吸”微生物自然产生的，在这些导线将能量电子传递到膜上后，它们将驱动酶催化产生氢气。我们的新型仿生光催化剂将为设计具有空间分离位点的均质光催化剂建立新的原理，用于燃料进化和维持这一过程所需的电子供应。我们设想，我们的光催化剂将被证明是多用途的，只要稍加修改，它们就能利用太阳能制造药物和精细化学品。

Reports concerning dwindling reserves of fossil fuels and concerns over fuel security are frequent news headlines. The rising costs of fuel are a daily reminder of the challenges faced by a global society with ever increasing energy demands. In this context it is perhaps surprising that so many of the renewable energy supplies available to us, namely, sunlight, winds and waves, remain largely untapped resources. This is mainly due to the challenges that exist in converting these energy forms into fuels from which energy can be released 'on demand' when we wish to play computer games, drive a car and so on. However, during plant photosynthesis fuels are made naturally from the energy in sunlight. Light absorption by the green chlorophyll pigments generates an energised electron that is directed, along chains of metal centres, to catalysts that make sugars. These sugars fuel us, and all animals, when their energy is released following digestion of a meal. However, using farmed plants to produce biofuels is controversial as agriculture is also required to feed the world. As a consequence, and inspired by natural processes, we propose to build a system for artificial photosynthesis. In essence, we wish to place tiny solar-panels on microbes in order to harness sunlight to drive the production of hydrogen - a fuel from which the technologies to release energy on demand are well-advanced. We will use dyes and semi-conductor particles as mechanically and chemically robust materials to capture the energy in sunlight and generate energised electrons. We will couple these particles to biology's version of conducting wires. These wires are made from heme proteins that span membranes that provide Nature's solution to compartmentalising water-filled chambers (i.e., the inside of the bacterium). The heme-wires are produced naturally by 'rock-breathing' microorganisms and after these wires have transferred the energised electrons across the membrane they will drive enzyme catalysis to produce hydrogen Our novel bio-mimetic photocatalysts will establish new principles for the design of homogeneous photocatalysts with spatially segregated sites for fuel-evolution and the supply of electrons that is needed to sustain this process. We imagine that our photocatalysts will proove versatile and that with slight modification they will be able to harness solar energy for the manufacture of drugs and fine chemicals.