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，需要为子孙后代确保一个健康的地球。城市和乡村景观中太阳能电池板的丰富立即表明，无论是在国家还是作为个人，我们都在拥抱技术来做到这一点。太阳能电池板吸收太阳光，并将其能量转化为电能。这有助于通过减少我们对化石碳储备的使用来缓解气候变化，利用阳光是非常明智的；在短短两个小时内，太阳为地球提供足够的能量来满足其目前的年度能源需求。然而，太阳能电池板并非没有问题，因为它们是用有毒材料建造的，而且时断时续地输出，这可能与能源需求的模式不匹配。开发更可持续的利用阳光能源的途径是一项全球性的挑战。为了帮助应对这一挑战，并受到绿色植物光合作用的启发，我们的目标是结合最好的自然和合成太阳能转换方法，以可持续地生产包括燃料在内的化学品。光合作用是大自然利用太阳能的方式。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，吸收阳光来推动脂肪和糖的合成。令人惊讶的是，这个反应的唯一副产品是我们呼吸所需的氧气。脂肪和糖提供了我们像植物一样的燃料，无论是白天还是黑夜，晴朗还是多云，我们都可以利用这些燃料来提供能量。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，但它并不是没有瓶颈。捕光系统只吸收一小部分太阳光谱，很容易损坏--在白天，它们通常每30分钟更换一次。相比之下，太阳能电池板中的合成捕光材料比自然光系统更坚固。此外，“彩虹吸收器”可以利用更多的太阳光谱。我们的研究将把坚固的合成捕光材料与非光合作用的细菌结合在一起，形成一种强大的、可持续的解决方案，以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(从生物柴油生产的主要未充分利用的副产品中提取)、氢(从水中提取)和甲酸盐(从二氧化碳中提取，这是一种温室气体)。重要的是，我们的生物混合燃料将同时产生两种不同的燃料，但没有副产品，因此它们在化学效率上是对自然光合作用的真实模拟。我们该怎么做呢？我们将利用蛋白质结构的详细知识，将电子从希瓦氏菌的内部传导到外部。这一知识使我们能够设计希瓦氏细菌的外表面，以便用捕光电催化剂进行选择性标记。然后，在太阳光的推动下，电子将在细菌内的酶催化剂和细菌外的合成催化剂之间移动，以便将细菌内一种燃料的产生与细菌外的另一种燃料的产生结合起来。我们的方法使我们能够使用酶来实现复杂的转化，而不需要昂贵的纯化，这可能会导致脆弱的系统。通过使用细菌，我们的系统的性能也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.