Growth of Staphylococcus aureus and Synthesis of Enterotoxin During Ripening of Experimental Manchego-Type Cheese

• Published in: Journal of dairy science 1992-01, Vol.75 (1), p.19-26
• Main Authors: Gómez-Lucía, Esperanza, Goyache, Joaquin, Orden, Jose A., Domenech, Ana, Javier Hernandez, F., Ruiz-Santa Quiteria, Jose A., Lopez, Belen, Blanco, Jose L., Suárez, Guillermo
• Format: Article
• Language: English
• Subjects: ALIMENTOS; Animals; BACTERIA; Biological and medical sciences; Cattle; Cheese; Colony Count, Microbial; CONTAMINACION; CONTAMINATION; CONTEO DE CELULAS; ENTEROTOXINAS; ENTEROTOXINE; enterotoxins; Enterotoxins - analysis; Enterotoxins - biosynthesis; ESPAGNE; ESPANA; Food industries; Food Microbiology; FROMAGE; Fundamental and applied biological sciences. Psychology; Goats; Hydrogen-Ion Concentration; MADURAMIENTO; Manchego-type cheese; Milk and cheese industries. Ice creams; MURISSAGE; NUMERATION CELLULAIRE; PRODUIT ALIMENTAIRE; QUESO; ripening; Sheep; STAPHYLOCOCCUS AUREUS; Staphylococcus aureus - growth & development; Staphylococcus aureus - metabolism
• ISSN: 0022-0302; 1525-3198
• DOI: 10.3168/jds.s0022-0302(92)77733-9

To study the possible presence of staphylococcal enterotoxins in Manchego-type cheese, milk was inoculated with the enterotoxigenic Staphylococcus aureus collection strains FRI-100, S6, FRI-137, and FRI-472 to a final concentration of 10,000 to 25,000cfu/ml. Cheese was prepared following the industrial specifications and ripened for 60 d. Batches were prepared with 1 and .1% lactic acid culture and labeled with the abbreviated name of the strain and the concentration of lactic acid culture. Mean staphylococcal counts in .1% lactic bacteria cheeses were usually more than 1 log higher than the corresponding 1% ones. Staphylococcal counts declined markedly after d 35 to 42, and, by the end of ripening, they had disappeared from some cheeses. Enterotoxins were present in five of the cheeses, three prepared with .1% and two with 1% lactic bacteria. Enterotoxins detected were A and D, the enterotoxins most commonly associated with human intoxication. The maximum level of enterotoxin A detected in cheese with strain FRI-100 and with the .1% culture was 222ng/100g of cheese; in cheese FRI-100 with 1%, 111 ng/100g; in cheese S6 with .1%, 769ng/100g; and in cheese S6 with 1%, 33ng/l00g. Maximum level of enterotoxin D detected in cheese FRI-472 with .1% was 38 ng/100g.