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Metabolic Engineering of Bacillus megaterium for the Production of β-alanine
Subbi Rami Reddy Tadi,Ganesh Nehru,Senthilkumar Sivaprakasam 한국생물공학회 2022 Biotechnology and Bioprocess Engineering Vol.27 No.6
The safe production of β-alanine (BA) has attracted significant attention by its multifaceted applications in pharmaceutical, polymer, and nutrition. The extant highyielding 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-α-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. NADHdependent 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)2SO4, 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.