Intense pulsed light for inactivation of foodborne gram-positive bacteria in planktonic cultures and bacterial biofilms

Abstract Nowadays, food quality and safety issues caused by foodborne pathogens and spoilage bacteria have attracted widespread attention. This study examined effectiveness of intense pulsed light (IPL) treatment on the inactivation of seven foodborne gram-positive bacteria, including Staphylococcus aureus, Bacillus cereus, Listeria monocytogenes, Enterococcus faecium, Bacillus thuringiensis, Lactobacillus brevis, and Pediococcus acidilactici. The bacteria of three survival states, including planktonic, early (8 h) and mature biofilm (48 h), and in two biofilm models, including 96 well cell culture plate and polycarbonate membrane were cultivated, which were treated by IPL with three fluences (0.0407, 0.0319 and 0.0150 J*cm−2) under different number of pulses at 25 °C and 4 °C. Results showed that high level inactivation under different conditions were achieved and the inactivation rate improved with the increasing of fluence and pulse number. Moreover, mature biofilm had the strongest resistance ability to IPL, followed by early biofilm, while both of them were far more resistant than planktonic state. IPL may provide a means of surface decontamination, thereby reducing the contamination of microorganisms on the food surface.