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KMID : 1094720220270060909
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Biotechnology and Bioprocess Engineering
2022 Volume.27 No. 6 p.909 ~ p.920
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Metabolic Engineering of Bacillus megaterium for the Production of β-alanine
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Subbi Rami Reddy Tadi
Ganesh Nehru
Senthilkumar Sivaprakasam
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Abstract
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The safe production of β-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-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. 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)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.
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KEYWORD
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β-alanine, Bacillus megaterium, gene dosage, L-aspartate-α-decarboxylase, phosphoenolpyruvate carboxylase
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