Integration of a CO2-fixation pathway and PAN2 truncation in Saccharomyces cerevisiae for low-carbon single-cell protein production

초록

Anthropogenic carbon dioxide (CO2) emissions drive global climate change, motivating the development of bioprocesses that improve carbon utilization and enable CO2 recycling. In this study, we developed a CO2-fixing Saccharomyces cerevisiae chassis for single-cell protein (SCP) production using xylose derived from cellulosic biomass as a carbon source. A RuBisCO- based CO2-fixation pathway was previously integrated into a xylose-utilizing strain, enabling the routing of CO2 into central metabolism. Flux balance analysis combined with C-13-based intracellular metabolite analysis verified the assimilation of externally supplied CO2 into central metabolism, suggesting the potential for assimilation of fermentation-derived CO2 and improved carbon utilization during SCP production. To enhance SCP production, the PAN2 gene encoding a component of the poly(A)-ribonuclease complex, previously associated with increased global protein production in S. cerevisiae, was truncated in the CO2-fixing strain. Under anaerobic conditions, the engineered strain exhibited a significant increase in cellular protein content, accompanied by an overall upward trend in amino acid levels relative to the parental strain. Collectively, these results metabolically verify RuBisCO-mediated CO2-fixation in yeast strain and demonstrate the feasibility of coupling CO2-fixation to SCP production. This work also provides insights into the potential of integrating CO2-fixation with renewable carbon metabolism and establishing a proof-of-concept platform for the development of low-carbon yeast bioprocess.

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