Artificial switches induce the bespoke production of functional compounds in marine microalgae Chlorella by neutralizing CO2

To improve the CO2 tolerance of a marine microalga Chlorella sp. of which the production capacity has been demonstrated industrially, a mutant library was created and a strain hct53 was screened. Compared to the parental strain, hct53 shows a high CO2 capture capacity, while starch biosynthesis is compromised, with increases in health beneficial metabolites and antioxidant capacity. Global gene expression and genome-wide mutation distribution revealed that transcript choreography was concomitant with more active CO2 sequestration, an increase in the lipid synthesis, and a decrease in the starch and protein synthesis. These results suggest that artificial trait improvement via mutagenesis, couple with multiomics analysis, helps discover genetic switches that induce the bespoke conversion of carbon flow from "redundant metabolites" to valuable ones for functional food.