Enterobacter cloacae, isolated from the rhizosphere of cucumbers, produces large amounts of indole-3-acetic acid. Indolepyruvate decarboxylase, the key enzyme in the biosynthetic pathway of indole-3-acetic acid, catalyses the formation of indole-3-acetaldehyde and carbon dioxide from indole-3-pyruvic acid. The enzyme requires the cofac-tors thiamine diphosphate andmagnesium ions for catalytic activity. Recombinant indolepyruvate decarboxylase was purified from the host Escherichia coli strain JM109
