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The bactericidal effect of antimicrobial blue light against foodborne pathogens and the underlying mechanism

Xiaoqing Hu, Shuanghua Luo, Xi Yang

The bactericidal effect of antimicrobial blue light against foodborne pathogens and the underlying mechanism: The alarming emergence of antibiotic resistance has necessitated the development of novel antimicrobial approaches. Antimicrobial blue light (aBL), in 405-470 nm, has attracted increasing attention as a safe and environmentally friendly technology. Compared with ultraviolet light, aBL has proven to be much less detrimental to mammalian cells and can penetrate deeper into tissue. aBL illumination showed broad-spectrum bactericidal effects against both clinical pathogens and foodborne pathogens such as Escherichia coli, Staphylococcus aureus, Cronobacter sakazakii and Salmonella typhimurium in our previous work. Up to now, aBL had been successfully applied in disinfection of some food, including cantaloupe rinds, fresh-cut papaya, milk, cucumbers, processed meat products and packaged sliced cheese, and we also employed aBL in the freshness maintaining of egg and beef. aBL dose at 54.6 J/cm2 caused a 3.73 log CFU reduction per eggshell surface and 109.44 J/cm2 inactivated 90% of inoculated cells on beef (P < 0.05). Furthermore, aBL had a negligible impact on their quality. Up to now, the antimicrobial mechanism of BL is still not fully understood. aBL excited the endogenous intracellular porphyrins, leading to the production of highly cytotoxic reactive oxygen species and the following oxidative damage of various biomolecules, such as DNA, proteins and lipids that resulting in cell death. We recently discovered by comparative lipidomics that most lipids of E. coli and S. typhimurium upon aBL irradiation had changed significantly and thereby damaged cell membrane.