Abstract

Salmonella Typhimurium is a widely distributed foodborne pathogen and is tolerant of various environmental conditions. It can cause intestinal fever, gastroenteritis and bacteremia. The aim of this research was to explore the effect of illumination with 405 nm light-emitting diodes (LEDs) on the resistance of S. Typhimurium to environmental stress. Beef slices contaminated with S. Typhimurium were illuminated by 405 nm LEDs (18.9 ± 1.4 mW/cm2) for 8 h at 4 °C; controls were incubated in darkness at 7 °C. Then, the illuminated or non-illuminated (control) cells were exposed to thermal stress (50, 55, 60 or 65 °C); oxidative stress (0.01% H2O2 [v/v]); acid stress (simulated gastric fluid [SGF] at pH 2 or 3); or bile salts (1%, 2%, or 3% [w/v]). S. Typhimurium treated by 405 nm LED irradiation showed decreased resistance to thermal stress, osmotic pressure, oxidation, SGF and bile salts. The transcription of eight environmental tolerance-related genes were downregulated by the illumination. Our findings suggest the potential of applying 405 nm LED-illumination technology in the control of pathogens in food processing, production and storage, and in decreasing infection and disease related to S. Typhimurium.

Highlights

  • Salmonella, a Gram-negative bacterium, is a worldwide foodborne pathogen [1]

  • Salmonellosis has four clinical patterns in humans: enteric fever, gastroenteritis, bacteremia, and other complications of nontyphoidal salmonellosis; it occurs in a chronic-carrier state

  • The objective of this research was to evaluate the effect of 405 nm light-emitting diodes (LEDs)-illumination on the survival of S

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Summary

Introduction

Salmonella, a Gram-negative bacterium, is a worldwide foodborne pathogen [1]. Salmonella enterica has six subspecies, each of which consists of different serovars [2]. Enteritidis are recognized as the main etiological agents of salmonellosis in foodborne disease outbreaks [3]. Salmonellosis has four clinical patterns in humans: enteric fever, gastroenteritis, bacteremia, and other complications of nontyphoidal salmonellosis; it occurs in a chronic-carrier state. The mortality rates of salmonellosis can be as high as 5–7% in some regions. Salmonella can multiply in different environments outside living hosts [4]. Foods such as cheese, peanut butter, bean sprouts, egg products and beef can be contaminated by S.

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