Development of Desiccation-Tolerant Probiotic Biofilms Inhibitory for Growth of Foodborne Pathogens on Stainless Steel Surfaces

Abstract

Lactic acid bacteria biofilms can be used to reduce foodborne pathogen contamination in the food industry. However, studies on growth inhibition of foodborne pathogens by inducing biofilm formation of antagonistic microorganisms on abiotic surfaces are rare. We developed a desiccation-tolerant antimicrobial probiotic biofilm. Lactobacillus sakei M129-1 and Pediococcus pentosaceus M132-2 isolated from fermented Korean foods were found to exhibit broad-spectrum antibacterial activity against Bacillus cereus, Escherichia coli O157:H7, Staphylococcus aureus, Listeria monocytogenes, and Salmonella enterica. Their biofilm levels were significantly (p < 0.05) higher on stainless steel than on polyethylene or ceramic. Biofilms of both isolates showed significantly (p < 0.05) enhanced resistance against desiccation (exposure to 43% atmospheric relative humidity) as compared with the isolates not in the biofilm form. The antimicrobial activity of the isolates was sustained in dried biofilms on stainless steel surface; the initial number of foodborne pathogens (average 7.0 log CFU/mL), inoculated on stainless steel chips containing L. sakei M129-1 or P. pentosaceus M132-2 biofilm decreased to less than 1.0 log CFU within 48 h. The lactic acid bacteria antibacterial biofilms developed in this study may be applied to desiccated environmental surfaces in food-related environments to improve microbiological food safety.

Keywords: biofilm; desiccation; lactic acid bacteria; stainless steel.

Figure 1

Biofilm formation by Lactobacillus sakei M129-1 and Pediococcus pentosaceus M132-2 on polystyrene chip (PC), stainless steel chip (SSC), and ceramic chip (CC) at (A) 5, 15, 25, or 35 °C for 3 days; and (B) 25 °C for 1, 2, 3, or 6 days. Different letters mean a significant difference (p < 0.05) between samples, following the Ducan’s multiple test.

Figure 2

Survival of Lactobacillus sakei M129-1, Pediococcus pentosaceus M132-2, and Leuconostoc lactis M111-1 attached to SSCs under a desiccation environment (43% relative humidity, RH; 25 °C). SSCs were incubated for up to 7 days.

Figure 3

Changes in populations of five pathogens, (A) Escherichia coli O157:H7, (B) Staphylococcus aureus, (C) Listeria monocytogenes, (D) Bacillus cereus, (E) Salmonella enterica, with or without biofilms of Lactobacillus sakei M129-1 or Pediococcus pentosaceus M132-2, when incubated at 25 °C and 43% (RH) for up to 48 h. Values represent the average of samples from each of the three experiments. Error bars represent standard deviations. Different letters mean a significant difference (p < 0.05) between samples, following the Ducan’s multiple test.