Overexpression of hemA and hemL in Bacillus subtilis Promotes Overexpression of 5-aminolevulinic Acid

Bacillus subtilis strains were constructed that overexpressed the glutamyl t-RNA reductase (HemA) and glutamyl t-RNA synthase (HemL). The target proteins accounted for 11 and 13% of the total soluble protein in maltose induced extracts, respectively. The culture media from these strains was red with wavelength maxima near 400 nm indicating elevated levels of porphyrins. The 5-aminolevulinic acid content for these strains reached 42.57 and 39.78 mg/L after 24 h of induced growth and 65.23 and 68.45 mg/L, respectively, after 60 h. Therefore, hemA and hemL overexpression enhanced the biosynthesis of 5-aminolevulinic acid and these strains can be used for its purification.