Fig. 2

The complementation and ALA accumulation experiments in recombinant E. coli. a The ALA auxotrophic E. coli JP1449 containing pGX. b The ALA auxotrophic E. coli SASX41B containing pHA. c The ALA auxotrophic E. coli GE1377containing pHL. d The ALA accumulation in recombinant E. coli DH5α expressing gltX, hemA and hemL from C. glutamicum. Complementation experiments using the ALA auxotrophic strains were grown in LB medium supplemented with 50 μg/mL ALA (ALA+) or without ALA (ALA−). The wild type E. coli DH5α was respectively transformed with pUC19, pGX, pHA and pHL, generating the strain PD19, PDGX, PDHA and PDHL. Samples were taken and measured at 24 h with an interval of 4 h. The results were the average of three individual experiments