β-Alanine production by L-aspartate-α-decarboxylase from Corynebacterium glutamicum and variants with reduced substrate inhibition

β-Alanine is an important precursor in the production of food additives, pharmaceuticals, and nitrogen-containing chemicals. Biological production of β-alanine may be successful with enzyme l-aspartate-α-decarboxylase (ADC). However, substrate inhibition of ADC limits the application of this enzyme. In this study, an error-prone PCR was conducted using the gene encoding ADC enzyme from Corynebacterium glutamicum as a template in order to establish a mutant library and a screening method for high-yielding β-alanine strains with mutant enzymes. Two mutants with high activity, panD-56 (ADC^R12V) and panD-134 (ADC^Q17A), were obtained from the library of 2000 mutated enzymes. Kinetic analysis also indicated that ADC^R12V and ADC^Q17A had higher substrate affinities and enzymatic reaction rates than the wild enzyme. Finally, the characteristics of the strain panD-56 were evaluated and the yield and productivity were found to reach 0.65 g/g and 1.31 g/L/h with 40 g/L L-aspartic acid. When the concentration of L-aspartic acid reached 100 g/L, the yield was still 0.45 g/g, which was 125% higher than the wild type thus showing less substrate inhabitation compared to the wild type and showing strong potential for industrial biocatalytic production of β-alanine.