Ammonium repression of cephalosporin production by Streptomyces clavuligerus.
Production of beta-lactam antibiotics took place during growth of Streptomyces clavulgerus in chemically defined medium. The specific activities of isopenicillin N synthetase ("cyclase"), isopenicillin N epimerase, and deacetoxycephalosporin C synthetase ("expandase") increased during the exponential phase of growth. Specific cephalosporin productivity during fermentation followed a similar pattern, reaching a maximum near the end of the growth phase and decaying rapidly in the stationary phase. Ammonium chloride depressed cephalosporin production, presumably as a result of repression of cyclase and expandase formation, but not of epimerase. No inhibitory effects on enzyme activity by ammonium were found. Addition of tribasic magnesium phosphate [Mg3(PO4)2 X 8H2O] prevented the repression of cyclase and markedly stimulated cephalosporin production. Cephamycin C and, in smaller amounts, O-carbamoyldeacetylcephalosporin C were the only cephalosporins detected. Growth with ammonium resulted in lower titers of both compounds, and did not change the relative proportion of each. The correlation found between cephalosporin productivity and cyclase specific activity in different media suggests that formation of this enzyme may be the rate-limiting step in the pathway.
D000591:Amino Acid Isomerases / Q000378:metabolism; D000643:Ammonium Chloride / Q000494:pharmacology*; D001426:Bacterial Proteins; D002511:Cephalosporins / Q000096:biosynthesis*; D002513:Cephamycins / Q000096:biosynthesis; D002851:Chromatography, High Pressure Liquid; D003470:Culture Media; D004798:Enzymes / Q000378:metabolism; D005285:Fermentation; D019751:Intramolecular Transferases; D007535:Isomerases / Q000378:metabolism; D008274:Magnesium / Q000494:pharmacology; D017616:Magnesium Compounds; D010088:Oxidoreductases; D046915:Penicillin-Binding Proteins; D010710:Phosphates / Q000494:pharmacology; D013302:Streptomyces / Q000187:drug effects / Q000201:enzymology / Q000254:growth & development / Q000378:metabolism*; D013379:Substrate Specificity; D013997:Time Factors
D001426:Bacterial Proteins; D002511:Cephalosporins; D002513:Cephamycins; D003470:Culture Media; D004798:Enzymes; D017616:Magnesium Compounds; D046915:Penicillin-Binding Proteins; D010710:Phosphates; D000643:Ammonium Chloride; C025071:deacetylcephalosporin C; C030781:magnesium phosphate; C000201:A16886A; D010088:Oxidoreductases; C038370:isopenicillin N synthetase; D007535:Isomerases; D000591:Amino Acid Isomerases; C040886:isopenicillin N epimerase; D019751:Intramolecular Transferases; C038371:deacetoxycephalosporin C synthetase; D008274:Magnesium; C024925:cephamycin C