Metabolic Engineering of Bacillus megaterium for the Production of β-alanine

The safe production of beta-alanine (BA) has attracted significant attention by its multifaceted applications in pharmaceutical, polymer, and nutrition. The extant high-yielding chemical and enzymatic methods of BA synthesis are handicapped by raw materials derived from petroleum resources, harsh reaction conditions, and catalyst instability. Consequently, this study explored a safe and alternative route via microbial fermentation, utilizing metabolic engineering of Bacillus megaterium to produce BA. The Bacillus subtilis panD gene (encoding L-aspartate-alpha-decarboxylase) was codon-optimized and overexpressed, which yielded 0.13 +/- 0.05 g/L BA. Aspartate ammonia-lyase (AspA) and aspartate aminotransferase (AspB) based pathways were examined for BA production from glucose. NADH-dependent glutamate dehydrogenase (gdh) was used to regenerate the cofactor NAD+ in the pathway with AspB. Dosing of the rate liming panD showed a positive effect on BA production. The BA titer was further increased to 1.4 +/- 0.06 g/L by over-expression of phosphoenolpyruvate carboxylase (PPC). Optimizing (NH4)(2)SO4, Pyridoxine, and NaHCO3 allowed the production of 2.41 +/- 0.15 g/L BA. Fed-batch fermentation of the final strain allowed 17.60 +/- 0.13 g/L BA production in 22 h. The present study has effectively unlocked the potential of engineering the B. megaterium for the sustainable production of the other ASP (L-aspartic acid) and BA-derived products at a large scale.

Automated summary

This study explored a safe and alternative route for the production of beta-alanine (BA) through microbial fermentation, achieving high yields through metabolic engineering. By optimizing gene expression and fermentation conditions, the production of BA was significantly increased, highlighting the potential of engineering Bacillus megaterium for sustainable production of related products.