Fig. 3.

Metabolic engineering for high kaempferol production in S. cerevisiae. a Metabolic pathway and engineering scheme for kaempferol production. Purple arrows represent reactions catalyzed by exogenous enzymes from plant in kaempferol synthesis pathway. Red arrows represent reactions catalyzed by endogenous enzymes in yeast, which are involved in the precursor synthesis, and overexpressed for kaempferol production. PAL, phenylalanine ammonia lyase; C4H, cinnamic acid 4-hydroxylase; 4CL, 4-coumaric acid ligase; CHS, chalcone synthase; CHI, chalcone isomerase; F3H, flavanone 3β-hydroxylase; FLS, flavonol synthase; ADH, alcohol dehydrogenase; ALD, aldehyde dehydrogenase; ACS, acetyl-coA synthetase; ACC, acetyl-CoA carboxylase. b OD₆₀₀ and production of naringenin, dihydrokaempferol and kaempferol in batch fermentation at 60 h. Glucose (20 g/L) was used as the sole carbon source. c OD₆₀₀ and production of naringenin, dihydrokaempferol and kaempferol in batch fermentation at 60 h. The media were supplemented with 20 g/L glucose and 1 mM p-coumarate. Data are shown as average ± standard division in triplicate tests