Survival characteristics of E. coli O157:H7, S. typhimurium and S. aureus during kefir fermentation

The growth and survival of E. coli O157:H7, Salmonella typhimurium, and Staphylococcus aureus were investigated during kefir fermentation using two different levels of inoculation as follows: 100 CFU/mL (EC-1, SA-1 and S-1) and 1,000 CFU/mL (EC-2, SA-2 and S-2). At 0, 2, 6, 12, and 24 hours of kefir fermentation at 23+/-1 deg C, samples were taken and the counts of E. coli O157:H7, S. typhimurium, and S. aureus were determined. EC-1 grew from 2.29+/-0.02 log CFU/mL to 4.13+/-0.18 log CFU/mL, whereas EC-2 grew from 3.22+/-0.04 log CFU/mL to 6.78+/-0.99 log CFU/mL. Sample S-1 varied from 2.37+/-0.20 log CFU/mL to 4.64+/-0.67 log CFU/mL, sample S-2 from 3.52+/-0.07 log CFU/mL to 5.60+/-0.10 log CFU/mL, SA-2 strains from 3.06 log CFU/mL to 3.64 log CFU/mL, and SA-1 strains from 2.28 log CFU/mL to 2.66 log CFU/mL. According to our findings, E. coli O157:H7, S. typhimurium, and S. aureus can survive in kefir during fermentation.