Fig. 3

Stability of L-cysteine producing phenotypes. A: Plasmids used for transformation in E. coli W3110 and MDS42 to study the stability of L-cysteine production. Boxed arrows indicate genes located on the plasmid, whereas bended arrows display corresponding promoters. B-E: Plots of relative L-cysteine yields in % (B + D) and the population growth rates (C + E) as a function of the number of accumulated generations. Cultivation and subsequent L-cysteine yield measurements were carried out in biological triplicates of W3110 and MDS42 with the three different plasmids shown in Fig. 3A. L-cysteine yields were normalised based on the OD₆₀₀ and the highest yield of the corresponding biological replicate (Additional file 1: fig. S1). Population growth rates were normalised based on growth rates of the corresponding non-producing strains harbouring empty vectors (Additional file 1: table S3)