Fig. 4: Effects of metabolic engineering of the MVA pathway on pleuromutilin production.

(a) The ethanol fermentation and MVA pathways with the enzymes catalysing each reaction. The process with the protein indicated as blue box was blocked by gene deletion, and those with the proteins indicated as orange box were potentiated by gene overexpression. To activate HMGRs, their truncated variants were also overexpressed. b The cartoons indicate the wA loci of the indicated strains. Pleuromutilin production (c) and extracellular/intracellular mevalonate amount (d) in the indicated strains. The numbering of each strain corresponds to the strain numbering in the panel b. The strains were cultured in MPY liquid medium at 30°C for 5 days. “Δ” indicates deletion of adh, “O/E” indicates overexpression of the corresponding genes, and “O/E-tr” indicates overexpression of the truncated HMGR genes. Data are shown as means ± standard deviation (S.D.) with dot plot indicating each data of three independent experiments. Data are analysed using Tukey’s (c) and Holm’s (d) multiple comparison test, and means sharing the same letter are not significantly different (p > 0.05). The significance of intracellular mevalonate is indicated as a’ and b’ (d).