Fig. 4.

23BD production in modified strains. (A) Schematic representation of recombination to integrate alsS, alsD, and adh into the S. elongatus chromosome. (B) Production in modified E. coli. Cells were grown for 40 h. Bars represent acetoin (light blue), (R,R)-23BD (red), and meso-23BD (dark blue). alsS indicates inclusion (+) of alsS (B. subtilis). alsD and adh rows indicate the source organism for the gene (Table S3). Activity is that of sADH expressed in E. coli and measured in cell extract (nmol NADPH min⁻¹⋅mg⁻¹). (C) 23BD production in modified S. elongatus. Cells were grown for 72 h. (D) Specific activities of ALS and sADH in cell extracts from modified S. elongatus strains. (E) Effect of IPTG in modified S. elongatus. Cells were grown for 72 h after induction with the specified concentration of IPTG. Values are normalized to those from uninduced cultures. Bars represent 23BD production (dark blue), activity of sADH protein measured with NADPH as cofactor (red), and activity of ALS protein (light blue). Error indicates SD (n = 3). A. h., A. hydrophila; B. l., B. licheniformis; B. s., B. subtilis; C. p., C. parapsilosis; C. b., C. beijerinckii; E. a., E. aerogenes; E. c., E. cloacae; G. x., G. xylinus; L. p., L. pseudomesenteroides; T. b., T. brockii.