Staphylococcus aureus is a major food-borne pathogen due to the production of enterotoxin and is particularly prevalent in contaminated milk and dairy products. The lactic acid bacteria (LAB) are widely used as biocontrol agents in fermented foods which can inhibit pathogenic flora. In our work, we investigated the influence of three strains of LAB (Lactobacillus plantarum, Streptococcus thermophilus and Enterococcus durans) on the relative expression of three enterotoxin genes (sea, sec, sell) and eight virulence and/or regulatory genes (sarA, saeS, codY, srrA, rot, hld/RNAIII, agrA/RNAII, sigB) in two S. aureus strains (MW2 and Sa1612) in TSB and reduced-fat milk (1.5 %) at 30 °C over a 24-h period. The tested LAB and S. aureus strains proved to be mutually non-competitive or only slightly competitive during co-cultivation. In addition, under the above-mentioned conditions, differential gene expression between the S. aureus MW2 and Sa1612 strains was well documented. S. aureus growth was changed in mixed culture with LAB; however, its effect on the repression of sea and sec expression correlated with production of these virulence factors. In comparison, the presence of LAB strains generally inhibited the expression of sec, sell, sarA, seaS, agrA/RNAII and hld/RNAIII genes. The effect of LAB strains presence on the expression of sea, codY, srrA, rot and sigB genes was medium, time, LAB and S. aureus strain specific. SEA and SEC production was significantly reduced in milk compared to TSB in pure culture. After the 24-h cultivation, S. aureus MW2 and Sa1612 SEC production was 187 and 331 times lower in milk compared to TSB, respectively (0.07 and 0.39 ng/mL in milk, versus 13.1 and 129.2 ng/mL in TSB, respectively). At the same time S. aureus MW2 and Sa1612 SEA production was 77 and 68 times lower in milk compared to TSB, respectively (0.99 and 0.17 ng/mL in milk, versus 76.4 and 11.5 ng/mL in TSB, respectively). This study has revealed new insights into the interaction between S. aureus and LAB (L. plantarum, S. thermophilus, E. durans) on the level of the expression and/or production of S. aureus enterotoxins, regulatory and virulence genes in different media, including milk. This study provides data which may improve the quality of food production.

Department of Bacteriology Veterinary Research Institute Brno Czech Republic

Department of Biochemistry and Microbiology University of Chemical and Technology Prague Czech Republic

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J Hyg (Lond). 1938 Nov;38(6):732-49 PubMed

Environ Microbiol Rep. 2011 Jun;3(3):340-51 PubMed

Food Microbiol. 2014 Dec;44:54-9 PubMed

Appl Environ Microbiol. 2009 Jul;75(13):4459-72 PubMed

Genome Biol. 2002 Jun 18;3(7):RESEARCH0034 PubMed

Proc Natl Acad Sci U S A. 2011 Feb 22;108(8):3360-5 PubMed

Appl Microbiol. 1973 May;25(5):770-3 PubMed

Biomed Res Int. 2014;2014:827965 PubMed

J Appl Microbiol. 2005;99(1):77-84 PubMed

FEMS Microbiol Rev. 2012 Jul;36(4):815-36 PubMed

Lancet. 2002 May 25;359(9320):1819-27 PubMed

Annu Rev Genet. 2008;42:541-64 PubMed

Appl Environ Microbiol. 2010 Mar;76(5):1367-74 PubMed

Food Microbiol. 2009 Dec;26(8):896-904 PubMed

Nucleic Acids Res. 2001 May 1;29(9):e45 PubMed

Chem Rev. 2011 Jan 12;111(1):117-51 PubMed

Clin Chem. 2009 Apr;55(4):611-22 PubMed

Appl Environ Microbiol. 1990 Feb;56(2):555-9 PubMed

Food Microbiol. 2015 Oct;51:163-70 PubMed

Food Microbiol. 2008 May;25(3):502-8 PubMed

BMC Microbiol. 2010 May 20;10:147 PubMed

Toxins (Basel). 2010 Jul;2(7):1751-73 PubMed

Appl Environ Microbiol. 2009 Jul;75(13):4473-82 PubMed

Virulence. 2011 Nov-Dec;2(6):580-92 PubMed

Int J Food Microbiol. 2007 Apr 20;115(3):290-6 PubMed

Appl Environ Microbiol. 2014 Nov;80(22):7028-35 PubMed

J Bacteriol. 2004 Apr;186(8):2430-8 PubMed

J Appl Microbiol. 2008 Nov;105(5):1327-33 PubMed

Int J Food Microbiol. 2008 Jan 15;121(1):60-5 PubMed