β-Alanine (β-Ala) is an important intermediate with numerous applications in food and feed additives, pharmaceuticals, polymeric materials, and electroplating industries. Its biological production routes that employ L-aspartate-α-decarboxylase (ADC) as the key enzyme are attractive. In this study, we developed an efficient and environmentally safe method for β-Ala production by co-expressing two different subtypes of ADC. A bacterial ADC from Bacillus subtilis (BSADC) and an insect ADC from Tribolium castaneum (TCADC) use pyruvoyl and pyridoxal-5'-phosphate (PLP) as cofactor, respectively. 3050 mM (271.5 g/L) β-Ala was achieved from L-aspartic acid by using the whole-cell biocatalyst co-expressing BSADC and TCADC, corresponding to a conversion rate of 92.4%. Meanwhile, one-pot synthesis of β-Ala from fumaric acid through using a tri-enzyme cascade route with two different subtypes of ADC and L-aspartase (AspA) from Escherichia coli was established. 2250 mM (200.3 g/L) β-Ala was obtained from fumaric acid with a conversion rate of 90.0%. This work proposes a novel strategy that improves β-Ala production in the decarboxylation pathway of L-aspartic acid.
Keywords: Co-expression; L-aspartase; L-aspartate-α-decarboxylase; Tri-enzyme cascade; Whole-cell biocatalyst; β-alanine.