Metabolic engineering of Corynebacterium glutamicum for efficient production of 5-aminolevulinic acid.

Abstract

5-Aminolevulinic acid (5-ALA) has recently attracted attention for its potential applications in the fields of medicine and agriculture. In this study, Corynebacterium glutamicum was firstly engineered for 5-ALA production via the C4 pathway. HemA encoding 5-aminolevulinic acid synthase from Rhodobacter sphaeroides was codon optimized and expressed in C. glutamicum ATCC13032, resulting in accumulation of 5-ALA. Deletion of all known genes responsible for the formation of acetate and lactate further enhanced production of 5-ALA. Overexpression of ppc gene encoding phoenolpyruvate carboxylase resulted in an accumulation of 5-ALA up to 2.06 ± 0.05 g/L. Furthermore, deletion of high-molecular-weight penicillin-binding proteins (HMW-PBPs) genes pbp1a, pbp1b, and pbp2b led to an increase in 5-ALA production of 13.53%, 29.47%, and 22.22%, respectively. Finally, 5-ALA production was enhanced to 3.14 ± 0.02 g/L in shake flask by heterologously expressing rhtA encoding threonine/homoserine exporter, and 86.77% of supplemented glycine was channeled toward 5-ALA production in shake flask. The engineered C. glutamicum ALA7 strain produced 7.53 g/L 5-ALA in a 5 L bioreactor. This study demonstrated the potential utility of C. glutamicum as a platform for metabolic production of 5-ALA. Change of cell permeability by metabolic engineering HMW-PBPs may provide a new strategy for biochemicals production in Corynebacterium glutamicum. Biotechnol. Bioeng. 2016;113: 1284-1293. © 2015 Wiley Periodicals, Inc.