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Antibacterial effect and mechanism of high-intensity 405±5nm light emitting diode on Bacillus cereus, Listeria monocytogenes, and Staphylococcus aureus under refrigerated condition
- Kim, Min-Jeong, Mikš-Krajnik, Marta, Kumar, Amit, Ghate, Vinayak, Yuk, Hyun-Gyun
- Journal of photochemistry and photobiology 2015 v.153 pp. 33-39
- Bacillus cereus, DNA, DNA damage, Listeria monocytogenes, Staphylococcus aureus, Weibull statistics, antibacterial properties, lighting, pathogens, sodium chloride
- This study investigated the antibacterial effect of 405±5nm light emitting diode (LED) on Bacillus cereus, Listeria monocytogenes, and Staphylococcus aureus, and examined its antibacterial mechanism by determining the bacterial membrane and DNA damages. A 405±5nm LED illuminated the Gram-positive pathogens until 486J/cm2 at 4°C. Weibull model was used to calculate reliable life (tR) to compare bacterial sensitivities to LED illumination. The membrane damage was determined by NaCl and LIVE/DEAD® assay, while comet assay and DNA ladder analysis were conducted to determine DNA degradation. The illumination resulted in 1.9, 2.1, and 1.0 log reductions for B. cereus, L. monocytogenes, and S. aureus at 486J/cm2, respectively. The comparison of tR values revealed that L. monocytogenes was identified as the most susceptible strain to LED illumination. The percentage of the bacterial sensitivity to NaCl remarkably increased in LED-illuminated cells compared to non-illuminated cells. Moreover, loss of membrane integrity was confirmed for LED-illuminated cells by LIVE/DEAD® assay, whereas no DNA breakage was indicated by comet assay and DNA ladder analysis. Thus, these findings suggest that the antibacterial effect of 405±5nm LED illumination on these pathogens might be due to physical damage to bacterial membrane rather than DNA degradation.