Biohybrids for Solar Chemicals and Fuels: Whole-cell Photocatalysis by Non-photosynthetic Organisms.

从新闻头条到社交媒体流，我们不断被提醒需要为子孙后代保护一个健康的地球。城市和乡村景观中丰富的太阳能电池板立即说明，无论是国家还是个人，我们都在拥抱技术来实现这一目标。太阳能电池板吸收阳光并将其能量转化为电能。这有助于减缓气候变化，减少我们对化石碳储备的使用，利用阳光是非常明智的；太阳在短短两小时内为地球提供了足够的能量，以满足目前地球每年的能源需求。然而，太阳能电池板也不是没有问题，因为它们是用有毒材料建造的，并且存在间歇性输出，这可能与能源需求的模式不匹配。开发更可持续的路线来利用太阳能是一项全球性挑战。为了帮助应对这一挑战，并受到绿色植物光合作用的启发，我们的目标是将最好的自然和合成方法结合起来进行太阳能转换，以实现包括燃料在内的化学品的可持续生产。光合作用是大自然利用太阳能的一种方式。绿色植物利用丰富的无毒元素组装成对环境无害的蛋白质，吸收阳光来驱动脂肪和糖的合成。令人惊讶的是，这个反应的唯一副产品就是我们需要呼吸的氧气。脂肪和糖为我们提供燃料，就像植物一样，无论白天还是晚上，晴天还是阴天，我们都可以利用它们来提供能量。自然光合作用是一种自我维持的、可再生的太阳能转换模式，但它并非没有瓶颈。光收集系统只吸收太阳光谱的一小部分，而且很容易损坏——白天它们通常每30分钟更换一次。相比之下，合成的光收集材料，如太阳能电池板，比天然光系统更坚固。此外，“彩虹吸收器”可以利用更多的太阳光谱。我们的研究将把强大的合成光收集材料与非光合细菌结合起来，以一种强大的、可持续的解决方案来实现复杂的化学转化。我们的目标是开发生产燃料的系统，例如乙醇（来自生物柴油生产中未充分利用的主要副产品）、氢（来自水）和甲酸（来自温室气体二氧化碳）。重要的是，我们的生物杂交将同时产生两种不同的燃料，但没有副作用，因此它们在化学效率上是真正模仿自然光合作用的。我们该怎么做呢？我们将使用蛋白质结构的详细知识，将电子从内部传导到外部的希瓦氏菌。这些知识使我们能够设计希瓦氏菌的外表面，用光收集电催化剂进行选择性标记。然后，在阳光能量的驱动下，电子将在细菌内部的酶催化剂和细菌外部的合成催化剂之间移动，以便将细菌内部的一种燃料和细菌外部的另一种燃料的生产结合起来。我们的方法允许我们使用酶来实现复杂的转化，而无需昂贵的纯化，这可能导致脆弱的系统。通过使用细菌，我们的系统的性能也有可能受益于酶的自我修复和再生的自然过程。

From news headlines to social media streams, we are constantly reminded of the need to help secure a healthy planet for future generations. The abundance of solar panels in urban and rural landscapes immediately illustrates how, nationally and as individuals, we are embracing technology to do this. Solar panels absorb sunlight and convert its energy to electricity. This helps to mitigate against climate change by lowering our use of fossil carbon reserves and harnessing sunlight is very sensible; in just two hours the sun provides Earth with sufficient energy to meet its present annual energy demand. However, solar panels are not without problems since they are constructed with toxic materials and suffer from intermittent output, which may not match patterns of energy demand. Developing more sustainable routes to harness the energy of sunlight is a global challenge. To help meet this challenge, and inspired by photosynthesis in green plants, we aim to combine the best of natural and synthetic approaches to solar energy conversion for the sustainable production of chemicals including fuels.Photosynthesis is Nature's way of harnessing solar energy. Using abundant and non-toxic elements assembled as environmentally benign proteins, green plants absorb sunlight to drive the synthesis of fats and sugars. Amazingly, the only side-product of this reaction is the oxygen we need to breath. Fats and sugars provide fuels that we, like plants, can use for energy whether it is day or night, sunny or cloudy. Natural photosynthesis is a self-sustaining, renewable model for solar energy conversion but it is not without bottlenecks. The light-harvesting systems absorb only a small fraction of the solar spectrum and are easily damaged - during the day they are usually replaced every 30 minutes. By contrast, synthetic light-harvesting materials like those in solar panels, are more robust than natural photosystems. In addition 'rainbow absorbers' can harness much more of the solar spectrum. Our research will combine robust, synthetic light-harvesting materials with non-photosynthetic bacteria in a powerful, sustainable solution to delivering complex chemical transformations. We aim to develop systems producing fuels, for example, ethanol (from a major underutilised by-product of biodiesel production), hydrogen (from water) and formate (from carbon dioxide a greenhouse gas). Importantly our biohybrids will simultaneously produce two different fuels but no side products so they are true mimics of natural photosynthesis in their chemical efficiency. How will we do this? We will use detailed knowledge of the structure of a protein conducting electrons from the inside to the outside of Shewanella bacteria. This knowledge allows us to engineer the external surface of the Shewanella bacteria for selective labelling with light-harvesting electrocatalysts. Then, powered by the energy of sunlight, electrons will move between enzyme catalysts inside the bacteria and the synthetic catalyst outside the bacteria in order to couple the production of one fuel inside the bacterium and a different fuel outside the bacterium. Our approach allows us to use enzymes to deliver complex transformations without expensive purification that can result in fragile systems. By using bacteria there is also the possibility that the performance of our systems will benefit from natural processes of enzyme self-repair and regeneration.