Effect of cold atmospheric plasma on growth and biofilm formation of Staphylococcus aureus isolated from mastitic bovine milk

Staphylococcus aureus is one of the most important pathogenic bacteria in the dairy products industry that is capable of biofilm formation. Biofilm formation by these bacteria has been led to resistance to antimicrobial agents. Inactivation of microorganisms using cold atmospheric plasma is one of the new approaches in the food industry. In this study, to evaluate the antibacterial and anti-biofilm effect of cold atmospheric plasma, a dielectric barrier discharge system was used. Twenty isolates of S. aureus from clinical bovine mastitis milk were exposed to plasma from 5 to 20 Sec and their antibacterial activity was estimated by recording the growth zone of inhibition. Plasma treatment was performed punctually for 5 Sec to assess the possible effects of plasma treatment on bacterial biofilm-formation activity after 24 h. The results show that a remarkable reduction in the growth of bacteria by increasing the flow of plasma. Moreover, statistical analysis of the ELISA reader results showed that the exposure of the isolates to plasma, significantly (p< 0.05) reduced the biofilm formation. These results suggest that plasma can be a suitable alternative method for thermal sterilization techniques. However, its application requires further studies to determine the severity and duration of exposure of microorganisms to plasma.