Exceeding Conventional Maximum Carbon Yields via Heterotrophic CO2 Fixation

However, microorganisms, particularly heterotrophs, release carbon dioxide (CO2) during the oxidation of organic compounds for energy and building blocks. This metabolism limits the theoretical maximum carbon yield and constrains the development of efficient microbial cell factories.

Specifically, metabolite production from tricarboxylic acid (TCA)-cycle intermediates involves major CO2 emission steps, leading to unavoidable carbon loss. In the present study, the metabolic pathway in Escherichia coli, a model heterotroph, was synthetically rewired to facilitate CO2 fixation and maximize carbon yields. Specifically, we blocked multiple routes to prevent pyruvate oxidation to acetyl-CoA, which was identified as a major CO2 emission step, and promoted CO2 incorporation into TCA cycle intermediates by reengineering endogenous pathways.