Electro-fermentation process design for efficient CO2 conversion into value-added products

化学工业严重依赖原油，这是一种有限和不可持续的资源，具有全球价格波动，对全球经济产生负面影响。石油化工储量的枯竭，加上引发恶劣天气事件的全球碳排放空前上升，是开发无害环境、可持续的替代能源并遏制我们对化石资源的依赖的驱动力。使用微生物细胞工厂的工业生物技术已经进入这样一个时代，在这个时代，生物工程中的科学和技术进步可以大大促进使用可再生碳原料的可持续产品开发。利用二氧化碳或甲烷等废物和温室气体生产有价值的产品，从而减少碳排放并创造净零循环经济，应是各国政府可持续工业脱碳政策的重点。这些废气有可能成为第三代可持续和技术经济可行的原料。与厌氧细菌相比，C1型需氧细菌具有更广泛的产气谱、更高的生产力和遗传适应性等显著优势。然而，H2和O2混合物的可燃性限制了好氧气体发酵中的最佳O2浓度。较低的氧气浓度意味着较高的传质要求是可行的发酵过程所必需的。这在典型的工业好氧发酵中是一个已知的问题，在氧气浓度有限的好氧气体发酵中，这个问题只会加剧。因此，在工业气体发酵的资本成本范围内，替代工艺设计对于经济上可行的工艺至关重要。微生物电合成将电化学和生物技术结合在一起，通过依赖废弃的原材料和可再生能源来实现资源节约型工艺。电生物技术致力于将电力转化为化学品的概念，以缩小甚至缩小能源和化学部门之间的差距。产电/电活性细菌(EAB)是胞外电子传递途径的天然载体，被广泛研究，但氧气敏感性和遗传工具的缺乏限制了这些细菌在生物修复方面的应用。在本项目中，我们旨在设计和建立一个生物处理平台，能够评估生物催化剂在生产增值化学品方面的电发酵潜力。这一平台将被用来阐明金属铜绿假单胞菌CH34的外部电子转移(EET)的遗传基础。这项合作的多学科研究旨在使用电化学表征和工程生物学中的互补方法来阐明和验证该细菌中的EET机制。接下来将展示其在生物电发酵过程中的潜力，从二氧化碳中生产出有价值的产品。阐明EET在这种细菌中的确切机制也将打开大门，潜在地将这一机制转移到它的近亲Cupriavidus Necator H16，它被证明是一种高效的自养细菌，将二氧化碳转化为高价值的产品。通过有效的知识交流活动，包括外展活动，我们将展示这项技术在当前化学工业中的整合，作为可持续工业脱碳的主要范例，利用PI(生物工艺引燃/开发)、Co-I(合成生物学)和国际合作伙伴(可持续电化学)的独特和互补的技能。

The chemical industries are heavily reliant on crude oil, a finite and unsustainable resource with global price fluctuations with negative impact on global economies. Depleting petrochemical reserves, coupled with unprecedented rise in global carbon emissions triggering severe weather events, represent the driving forces behind the development of environmentally sound, sustainable alternatives and to curb our reliance on fossil-based resources. Industrial biotechnology using microbial cell factories has entered an era where scientific and technological advances in bioengineering can contribute appreciably towards sustainable product development using renewable carbon feedstocks. Utilization of waste and greenhouse gases such as CO2 or CH4 to produce valuable products, thereby reducing carbon emissions and creating net-zero circular economies, should be at the forefront of the governments sustainable industrial decarbonization policies. These waste gases have the potential to become the third generation sustainable and techno economically feasible feedstocks. C1 gas consuming aerobic bacteria possess significant advantages over their anaerobic counterparts such as wider product spectrum, higher productivities and genetic amenability. However, the flammability concerns of H2 and O2 mixtures limit optimum O2 concentrations in aerobic gas fermentations. Lower O2 concentrations mean higher mass transfer requirements are necessary for a viable fermentation process. This is a known problem in a typical industrial aerobic fermentation and the problem is only exacerbated in aerobic gas fermentation where O2 concentration are limited. An alternative process design is therefore pivotal for an economically feasible process within the capital cost context of industrial gas fermentation.Microbial electrosynthesis combines electrochemistry and biotechnology in a resource-efficient processes by relying on waste raw materials and renewable energies. Electro-biotechnology strives for the concept of power-to-chemicals to narrow or even close the gap between the energy and the chemistry sector. Electrogenic /electroactive bacteria (EAB) such as, Geobacter sulfurreducens and Shewanella oneidensis are natural carriers of extracellular electron transfer pathways and are extensively studied, however O2 sensitivity and lack of genetic tools have limited the use of these bacteria mostly for bioremediation purposes.In this project we aim to design and set up a bioprocess platform that will enable the assessment of electro-fermentative potential of biocatalysts for the production of value-added chemicals. This platform will be used to elucidate the genetic basis of external electron transfer (EET) in Cupriavidus metallidurans CH34, a facultative anaerobic, CO2 consuming bacteria. This collaborative multidisciplinary study aims to use complimentary approaches in electrochemical characterisation and engineering biology to elucidate and validate the EET mechanism in this bacterium. This will be followed by demonstrating its potential in a bio-electro fermentation process, producing a valuable product from CO2. Elucidating the exact mechanism of EET in this bacterium will also open doors to potentially transfer this mechanism to its close relative, Cupriavidus necator H16 which is proven to be an efficient autotrophic bacterium converting CO2 to highly valuable products. With the unique and complementary skills from the PI (bioprocess enigneering/development), the Co-I (synthetic biology) and the international partners (sustainable electrochemistry), via effective knowledge exchange activities, including outreach activities, we will showcase the integration of this technology within the current chemical industries as a prime example for sustainable industrial decarbonisation.