Galactose induces the expression of penicillin acylase under control of the lac promoter in recombinant Escherichia coli.

The expression of penicillin acylase (PA), cloned in the pPA102 plasmid under control of the wild-type lac promoter and using galactose as inducer in Escherichia coli JM101, JM103 and JM105 transformant cells, was analyzed. The E. coli JM101/pPA102 cultures attained the highest specific activity of PA. For large scale PA production based on E. coli JM101/pPA102 a culture media with galactose instead of isopropyl-thio-galactopyranoside as inducer would be as successful and less expensive.