title: Expression and production of staphylococcal enterotoxin C is substantially reduced in milk.
abstract: Staphylococcal food poisoning is a global problem. The gene encoding enterotoxin C (sec) has been reported several times as the most frequent enterotoxin gene identified in food poisoning cases caused by contaminated milk. In this study, the expression of sec was examined during the growth of Staphylococcus aureus in milk compared to routinely used laboratory media. Additionally, expression of several regulatory genes (sarA, saeS, codY, srrA, rot, hld, agrA, sigB) and other five enterotoxin genes (sea, seg, seh, sek, sel) were observed. It has been well established for that S. aureus is able to grow in milk and we found significantly reduced expression of sec in milk compared to the laboratory medium (P < 0.05). Here, we report the first study providing a comprehensive view on the expression of enterotoxin genes and its regulation in milk. The milk environment dramatically changed the expression profiles of several enterotoxin genes although staphylococcal growth was not affected at all. The mechanism of the reduction may be explained by downregulation of the agr system, although other factors are expected to be involved. The constituent of milk causing the inhibitory effect remains unidentified.
authors.affiliation: Institute of Chemical Technology Prague, Faculty of Food and Biochemical Technology, Department of Biochemistry and Microbiology, Technicka 5, Prague, 166 28, Czech Republic.
authors.forename: Lukas
authors.initials: L
authors.lastname: Valihrach
authors.affiliation: Institute of Chemical Technology Prague, Faculty of Food and Biochemical Technology, Department of Biochemistry and Microbiology, Technicka 5, Prague, 166 28, Czech Republic. Electronic address: Babak.Alibayov@vscht.cz.
authors.forename: Babek
authors.initials: B
authors.lastname: Alibayov
authors.affiliation: Institute of Chemical Technology Prague, Faculty of Food and Biochemical Technology, Department of Biochemistry and Microbiology, Technicka 5, Prague, 166 28, Czech Republic.
authors.forename: Kamila
authors.initials: K
authors.lastname: Zdenkova
authors.affiliation: Institute of Chemical Technology Prague, Faculty of Food and Biochemical Technology, Department of Biochemistry and Microbiology, Technicka 5, Prague, 166 28, Czech Republic.
authors.forename: Katerina
authors.initials: K
authors.lastname: Demnerova
mesh_terms: D000818:Animals; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D015536:Down-Regulation; D004768:Enterotoxins / Q000235:genetics* / Q000378:metabolism*; D015870:Gene Expression; D008892:Milk / Q000382:microbiology*; D013211:Staphylococcus aureus / Q000235:genetics / Q000378:metabolism*
chemical_list: D001426:Bacterial Proteins; D004768:Enterotoxins; C034959:enterotoxin C, staphylococcal
keywords: ELISA; Enterotoxin C; Milk; RT-qPCR; Staphylococcus aureus; expression