Nitrogen regulation of urease synthesis inSaccharopolyspora erythraeaATCC 11365

Abstract

Urease is the enzyme that catalyzes the hydrolysis of urea to carbon dioxide and ammonia; regulation of the synthesis of this enzyme was studied in Saccharopolyspora erythraea, an erythromycin producer. Urease activity was determined when this microorganism was grown on urea and arnino acids as nitrogen sources. Higher enzyme levels were observed when glycine, proline or alanine were used, indicating synthesis of this enzyme does not require induction. Urea, whose hydrolysis generated high extracellular levels of ammonium, permitted a low production of urease. The presence of an ammonium salt in the culture medium repressed urease synthesis indicating that urease was under nitrogen repression. Addition of methylamine, a non-metabolizable analogue of ammonium, to a pre-grown culture with high urease activity provoked a decrease of the specific activity in the same way as ammonium chloride, indicating that ammonium itself was the effector of this regulation.