Discovery and remodeling of *Vibrio natriegens* as a microbial platform for efficient formic acid biorefinery

Formic acid (FA) has emerged as a promising one-carbon feedstock for biorefinery. However, developing efficient microbial hosts for economically competitive FA utilization remains a grand challenge. Here, we discover that the bacterium Vibrio natriegens has exceptional FA tolerance and metabolic capacity natively. This bacterium is remodeled by rewiring the serine cycle and the TCA cycle, resulting in a non-native closed loop (S-TCA) which as a powerful metabolic sink, in combination with laboratory evolution, enables rapid emergence of synthetic strains with significantly improved FA-utilizing ability. Further introduction of a foreign indigoidine-forming pathway into the synthetic V. natriegens strain leads to the production of 29.0 g·L−1 indigoidine and consumption of 165.3 g·L−1 formate within 72 h, achieving a formate consumption rate of 2.3 g·L−1·h−1. This work provides an important microbial chassis as well as design rules to develop industrially viable microorganisms for FA biorefinery.