Carbon capture and utilisation to replace sugar-based fermentations in the biotechnology industry

生物技术行业中碳捕获和利用取代糖基发酵

• 批准号: 2598001
• 金额: --
• 依托单位: University of Nottingham
• 依托单位国家: 英国
• 项目类别: Studentship
• 财政年份: 2021
• 资助国家: 英国
• 起止时间: 2021 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=studentship-2598001
• 关键词: Carbon; capture; utilisation; replace; sugar

Industrial biotechnology relies on agriculture to provide the input energy in the form of sugars for bacterial fermentations. Sugars are the carbon source and the energy source in these traditional setups. However, certain bacterial species are able to utilise carbon dioxide as their carbon source while relying on hydrogen gas as their energy source; these species are Hydrogen Oxidising Bacteria (HOB). The biochemical route exercised in HOB is the most efficient form of biological carbon fixation including photosynthetic algae. Several companies are attempting to commercialise the use of HOB to make Single Cell Protein (SCP), which is sold as a proteinaceous feed ingredient. As a feed ingredient SCP has major environmental advantages over traditional feed proteins: it has a lower overall carbon footprint in addition to a dramatically lower land and water use. However, for full uptake of the technology commercially the product must have sufficiently high value to compensate for the input costs and relatively high capital costs of a commercial plant. Adoption of this technology benefits from the ramp up in interest and scaling of the hydrogen economy. One particularly attractive route for improving the value of SCP is to co-produce other biological compounds of commercial interest such as dyes, flavourings, fragrances, or antioxidants. If these can be produced by the bacteria and extracted during downstream processing then the economics of SCP as a feed ingredient may become significantly more favourable. In the long-term the HOB will be engineered to compete technically with established species which currently make higher value compounds, but the HOB will have the advantage of using a hydrogen and carbon dioxide input stream rather than a sugar-based input. Established strains in industrial biotechnology are highly adapted or engineered to maximise productivity. HOB have not been the target of these manipulations historically because of a lack of inherent predisposition as a production organism. However, the ability to grow on a mixture of carbon dioxide and hydrogen is a highly desirable trait because of the environmental benefits of this process compared to one dependent on agricultural products as an input stream. In addition, this ability is not one that can be easily transferred to the established production strains. A far simpler approach would be to transfer the relevant properties from the established production strains to the HOB. Deep Branch has a library of HOB capable of growing on carbon dioxide. Within that library there are several strains for which a genetic toolkit has been developed which allows sophisticated genetic engineering to be performed. Escherichia coli is the most widely used species for expressing high value proteins largely because of the genetic toolkit which has been developed for it. This project aims firstly to emulate many of the developments which have made E. coli the dominant species in industrial biotechnology primarily by engineering strong protein expression systems comprising promoters, ribosome binding sites, and powerful dedicated RNA polymerases. Certain bacterial species are naturally well evolved to produce a given class of biological compound for instance an antibiotic. Other species would have evolved in such a way as to make them ideal candidates for the production of chemically dissimilar compounds such as dyes or flavours. To assess the suitability of the chosen HOB for the production of different classes of compounds a range of compounds will be chosen for expression. This will help to inform the most appropriate target for optimisation and deployment in a commercial setting. Another goal will be to increase the efficiency of carbon capture via protein engineering. This will involve identifying the bottleneck in the biochemical pathway of carbon fixation and making a library of different versions of the bottleneck protein.

工业生物技术依靠农业以糖的形式为细菌发酵提供输入能量。糖是这些传统装置中的碳源和能源。然而，某些细菌物种能够利用二氧化碳作为其碳源，同时依赖氢气作为其能源;这些物种是氢氧化细菌（HOB）。在HOB中行使的生化途径是生物碳固定的最有效形式，包括光合藻类。几家公司正在尝试将HOB用于生产单细胞蛋白（SCP）的商业化，SCP作为蛋白质饲料成分出售。作为一种饲料成分，SCP比传统饲料蛋白具有重大的环境优势：除了大大减少土地和水的使用外，它还具有较低的总体碳足迹。然而，要在商业上充分利用这一技术，产品必须具有足够高的价值，以补偿投入成本和商业工厂相对较高的资本成本。采用这种技术受益于氢经济的兴趣和规模的增加。提高SCP价值的一个特别有吸引力的途径是共同生产其他具有商业价值的生物化合物，如染料，调味剂，香料或抗氧化剂。如果这些可以由细菌产生并在下游加工过程中提取，那么SCP作为饲料成分的经济性可能会变得更加有利。从长远来看，HOB将被设计成在技术上与目前制造更高价值化合物的已建立物种竞争，但HOB将具有使用氢气和二氧化碳输入流而不是糖基输入的优势。在工业生物技术中建立的菌株是高度适应或工程化的，以最大限度地提高生产力。历史上，HOB并不是这些操作的目标，因为它缺乏作为生产生物体的固有倾向。然而，在二氧化碳和氢气的混合物上生长的能力是非常理想的特性，因为与依赖于农产品作为输入流的过程相比，该过程的环境益处。此外，这种能力并不容易转移到已建立的生产菌株中。一种简单得多的方法是将相关特性从已建立的生产菌株转移到HOB。深分支有一个HOB库，能够在二氧化碳上生长。在该文库中，有几种菌株已经开发了遗传工具包，可以进行复杂的遗传工程。大肠杆菌是最广泛使用的表达高价值蛋白的物种，这主要是因为已经为它开发了遗传工具包。大肠杆菌是工业生物技术中的优势物种，主要是通过工程化强蛋白表达系统，包括启动子、核糖体结合位点和强大的专用RNA聚合酶。某些细菌物种自然进化得很好，可以产生给定类别的生物化合物，例如抗生素。其他物种的进化方式使它们成为生产化学上不同的化合物（如染料或香料）的理想候选者。为了评估所选HOB用于生产不同类别化合物的适用性，将选择一系列化合物进行表达。这将有助于为商业环境中的优化和部署提供最合适的目标。另一个目标是通过蛋白质工程提高碳捕获效率。这将涉及确定碳固定生化途径中的瓶颈，并制作不同版本瓶颈蛋白的文库。