Fig. 2

Screening of ALASs from different sources for 5-ALA production. RpHemA, hemA from R. palustris, expressed using P_trc; RpHemO, hemO from R. palustris, expressed using P_trc; RsHemA, hemA from R. sphaeroides, expressed using P_trc; RpHemA_Ptuf, hemA from R. palustris, expressed using P_tuf; RpHemA_Psod, hemA from R. palustris, expressed using P_sod. Dark grey bars, 5-ALA production level; green bars, ALAS activity in crude extract. Strains with different ALASs were cultivated in shake flasks with modified M9 medium. The titer of 5-ALA at 36 h is shown. Cells were collected at the same time and lysed for ALAS activity assay. The reaction mixture contained 100 mM Tris–HCl (pH 7.5), 200 mM glycine, 0.2 mM succinyl-CoA, 0.1 mM pyridoxal phosphate (PLP) and 20 µg crude extract. After proceeding at 37 ℃ for 10 min, the reaction was terminated by the addition of 10% (v/v) trichloroacetic acid. Concentration of 5-ALA in the supernatant was determined. Error bars indicate standard deviations from three parallel experiments