Atmospheric CO2 poses a major threat to life on Earth by causing global warming and climate change. On the other hand, it can be considered as a resource that is scalable enough to establish a circular carbon economy. Accordingly, technologies to capture and convert CO2 into reduced one-carbon (C1) compounds (e.g. formic acid) are developing and improving fast. Driven by the idea of creating sustainable bioproduction platforms, natural and synthetic C1-utilization pathways are engineered into industrially relevant microbes. The realization of synthetic C1-assimilation cycles in living organisms is a promising but challenging endeavour. Here, we engineer the Serine Threonine Cycle, a synthetic C1-assimilation cycle in Escherichia coli to achieve growth on formic acid. Our stepwise engineering approach in tailored selection strains combined with adaptive laboratory evolution experiments enabled formatotrophic growth of the organism. Whole genome sequencing and reverse engineering allowed us to determine the key mutations linked to pathway activity. The Serine Threonine Cycle strains created in this work use formic acid as sole carbon and energy source and can grow at ambient CO2 cultivation conditions. This work sets an example for the engineering of complex C1-assimilation cycles in heterotrophic microbes.

中文翻译：

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大肠杆菌的进化辅助工程使在环境 CO2 下通过丝氨酸苏氨酸循环在甲酸上生长


大气中的 CO2 通过导致全球变暖和气候变化，对地球上的生命构成重大威胁。另一方面，它可以被视为一种具有足够可扩展性的资源，可以建立循环碳经济。因此，捕获 CO2 并将其转化为还原的一碳 （C1） 化合物（例如甲酸）的技术正在迅速发展和改进。在创建可持续生物生产平台理念的推动下，天然和合成的 C1 利用途径被设计成工业相关的微生物。在生物体中实现合成 C1 同化循环是一项有前途但具有挑战性的努力。在这里，我们设计了丝氨酸苏氨酸循环，这是大肠杆菌中的合成 C1 同化循环，以实现在甲酸上的生长。我们在定制选择菌株中的逐步工程方法与适应性实验室进化实验相结合，实现了生物体的形成营养型生长。全基因组测序和逆向工程使我们能够确定与通路活性相关的关键突变。这项工作中创建的丝氨酸苏氨酸循环菌株使用甲酸作为唯一的碳和能源，并且可以在环境 CO2 培养条件下生长。这项工作为异养微生物中复杂 C1 同化循环的工程设计树立了榜样。