Enzyme

Lactic acid

Lactococcus lactis

Propionate

Bacteria

Metabolic engineering

Biology

Fermentation

Phosphoenolpyruvate carboxykinase

Chemistry

Yeast

Industrial fermentation

Food science

Genetics

Biochemistry

Biotechnology Journal

Propionate is widely used as a preservative in the food and animal feed industries. Propionate is currently produced by petrochemical processes, and fermentative production of propionate remains challenging.In this study, a synthetic propionate pathway was constructed in the budding yeast Saccharomyces cerevisiae, for propionate production under aerobic conditions. Through expression of tdcB and aldH from Escherichia coli and kivD from Lactococcus lactis, L-threonine was converted to propionate via 2-ketobutyrate and propionaldehyde. The resulting yeast aerobically produced 0.21 g L-1 propionate from glucose in a shake flask. Subsequent overexpression of pathway genes and elimination of competing pathways increased propionate production to 0.37 g L-1 . To further increase propionate production, carbon flux was pulled into the propionate pathway by weakened expression of pyruvate kinase (PYK1), together with overexpression of phosphoenolpyruvate carboxylase (ppc). The final propionate production reached 1.05 g L-1 during fed-batch fermentation in a fermenter.In this work, a yeast cell factory was constructed using synthetic biology and metabolic engineering strategies to enable propionate production under aerobic conditions. Our study demonstrates engineered S. cerevisiae as a promising alternative for the production of propionate and its derivatives.

Metabolic engineering of threonine catabolism enables <i>Saccharomyces cerevisiae</i> to produce propionate under aerobic conditions

Metabolic engineering of threonine catabolism enables Saccharomyces cerevisiae to produce propionate under aerobic conditions