Effect of Increasing Zearalenone Levels on the Technologically Problematic Microorganisms and Food Risky Pathogens (in Vitro)

The aim of this study was to determine the effect of different zearalenone (ZEA) concentrations (0, 10, 100, 250, 500, 1 000 µg/l) on growth of Bacillus cereus, Staphylococcus aureus and Pseudomonas fluorescens in milk. The samples were incubated for 6 days at 22 and 30 °C (B. cereus and S. aureus) or at 6.5 and 22 ℃ (P. fluorescens), respectively. Counts of bacteria in milk were measured every 24 hours. Maximum counts of B. cereus after 144 h of incubation at 30 ℃ ranged from 7.00 to 7.78 log CFU/ml. The most significant effect of ZEA on B. cereus across the experiment was observed after 96 h of incubation at 22 °C and after 72 h at 30 °C (P < 0.001 and P < 0.01, respectively). S. aureus maintained at 30 °C showed similar growth parameters as at 22 ℃ regardless of ZEA presence. The most significant effects of ZEA on S. aureus were after 120 h of incubation at 22 °C and after 72 h at 30 °C (P < 0.001). The growth of P. fluorescence at 6.5 °C was slower compared to growth at 22 °C. The most significant effect of ZEA between ZEA spiked and Z0 samples on P. fluorescence across the experiment was observed after 48 hours of incubation at 22 °C (P < 0.001).