Enhancement of 5-aminolevulinic acid production by metabolic engineering of the glycine biosynthesis pathway in Corynebacterium glutamicum.

Abstract

To construct a strain of Corynebacterium glutamicum capable of efficiently producing 5-aminolevulinic acid (5-ALA) via the C4 pathway by modification of serine and glycine pathway using glucose as sole carbon source. The recombinant C. glutamicum strain AP2 harboring a codon-optimized hemA gene from Rhodobacter sphaeroides was used as host strain for 5-ALA production. A plasmid harboring the serine operon, which contained serB, serC and the site-specific mutant serA Δ197 , was constructed and introduced into C. glutamicumAP2, leading to an increase of 70% in 5-ALA production. Further overexpression of the glyA gene increased production of 5-ALA by 150% over the control. 5-ALA production was thus significantly enhanced by engineering the glycine biosynthetic pathway. C.glutamicum AG3 produced 3.4±0.2g 5-ALA/l in shake-flask cultures in CGIIIM medium with the addition of 7.5g glycine/l. This is the first report of remodeling the serine and glycine biosynthetic pathway to improve the production of 5-ALA in C. glutamicum.