Fig. 3

Optimization of the kaempferol biosynthetic pathway. (a) Comparison of kaempferol and dihydrokaempferol amount in yeast strains, which each has one, two, or three copies of AtFLS (FLS from A. thaliana). Cells were cultured in a defined minimal medium in shake flask conditions, and samples were taken after 72 h of growth for naringenin, dihydrokaempferol, and kaempferol detection. (b) Testing kaempferol producing strains in defined minimal medium in shake flask with six discs of FeedBeads, releasing glucose slowly and constantly. Samples were taken after 96 h of growth for naringenin, dihydrokaempferol, and kaempferol measurements. The black circle shows the existence of the gene in the strain, instead of the white circle representing its absence. Statistical analysis was performed by using one-way ANOVA, Tukey’s multiple comparison test (* < 0.05, ** < 0.01, *** < 0.001, ns, no significant difference). All data represent the mean ± standard deviation of 3 biologically independent samples