Fig. 2
Construction of the vgb expressing vector and comparisons of iLDHs activities and biotransformation rates toward pyruvate production between different P. putida KT2440 strains. a Construction of recombinant vector pBSPPcGm-vgb. vgb, the gene encoding VHb. pBSPPcGm, a broad-host-range constitutive vector containing a P c promoter. The vgb gene was inserted into the pBSPPcGm-vgb in the corresponding sites, to generate the plasmid pBSPPcGm-vgb. b Verification of pBSPPcGm-vgb. Lane M molecular mass standard (λDNA/HindIII); lane 1 product amplified with pET28b-RgDAAO-VHb as the template; lane 2 double enzymes digestion (HindIII and BamHI) of recombinant vector pBSPPcGm-vgb. c Activities of l-iLDH (violet bars) and d-iLDH (light magenta bars) in crude cell extracts of P. putida KT2440 and its derivatives were examined with DCIP as the artificial electron acceptor and 20 mM l- or d-lactate as the electron donor. Results are mean ± SD of three parallel replicates. d The biotransformation rates of pyruvate production by whole cells of different P. putida KT2440 strains. The biotransformations were conducted with the whole cells of P. putida KT2440, P. putida KT2440/pBSPPcGm-vgb, P. putida KT2440 (ΔlldR) and P. putida KT2440 (ΔlldR)/pBSPPcGm-vgb with 100 mM l-lactate (violet bars), 100 mM d-lactate (light cyan bars) and 100 mM dl-lactate (blue bars) as the substrates. The concentrations of the pyruvate were measured by HPLC. Results are mean ± SD of three parallel replicates