It is intended to provide a xanthomonas g(b)lactam acylase protein, a gene encoding this protein, a recombination vector having this gene and a transformant containing this recombination vector. A beta -lactam acylase gene of <i>Xanthomonas citri</i> is cloned and its DNA base sequence and an amino acid sequence deduced therefrom are determined. It is found out that the protein encoded by this gene is a protein consisting of 637 residues and having a molecular weight of 71 kDa and showing a beta -lactam acylase activity.
