Fig. 2

Metabolic engineering modification of the l-methionine terminal synthetic module. A Schematic diagram of MetA mutation sites. B The relative l-methionine titer of different mutant MetA-overexpressing strains in shake flask fermentation. C Production of l-methionine and growth of the MET1 and MET2 strains. D Flow chart of chromosomal integration for the metA^fbr, metC, and yjeH genes. E l-Methionine and l-isoleucine production and OD₆₀₀ of MET3, MET4, MET6, MET8, MET9, and MET10. Data are presented as the mean values with the standard deviation from three biological replicates. One-way analysis of variance (ANOVA) was used to determine significant differences (* p < 0.05, ** p < 0.01)