title: Antibacterial effect and mechanism of high-intensity 405 ± 5 nm light emitting diode on Bacillus cereus, Listeria monocytogenes, and Staphylococcus aureus under refrigerated condition.
abstract: This study investigated the antibacterial effect of 405 ± 5 nm 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 ± 5 nm LED illuminated the Gram-positive pathogens until 486 J/cm(2) 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 486 J/cm(2), 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 ± 5 nm LED illumination on these pathogens might be due to physical damage to bacterial membrane rather than DNA degradation.
authors.affiliation: Food Science & Technology Programme, Department of Chemistry, National University of Singapore, Science Drive 4, 117543, Singapore.
authors.forename: Min-Jeong
authors.initials: MJ
authors.lastname: Kim
authors.affiliation: Food Science & Technology Programme, Department of Chemistry, National University of Singapore, Science Drive 4, 117543, Singapore; Chair of Industrial and Food Microbiology, Faculty of Food Science, University of Warmia and Mazury in Olsztyn, Plac Cieszyński 1, 10-726 Olsztyn, Poland.
authors.forename: Marta
authors.initials: M
authors.lastname: Mikš-Krajnik
authors.affiliation: Food Science & Technology Programme, Department of Chemistry, National University of Singapore, Science Drive 4, 117543, Singapore.
authors.forename: Amit
authors.initials: A
authors.lastname: Kumar
authors.affiliation: Food Science & Technology Programme, Department of Chemistry, National University of Singapore, Science Drive 4, 117543, Singapore.
authors.forename: Vinayak
authors.initials: V
authors.lastname: Ghate
authors.affiliation: Food Science & Technology Programme, Department of Chemistry, National University of Singapore, Science Drive 4, 117543, Singapore; National University of Singapore (Suzhou) Research Institute, No. 377 Linquan Street, Suzhou Industrial Park, Suzhou, Jiangsu 215123, China. Electronic address: chmyukhg@nus.edu.sg.
authors.forename: Hyun-Gyun
authors.initials: HG
authors.lastname: Yuk
mesh_terms: D001409:Bacillus cereus / Q000528:radiation effects*; D002473:Cell Wall / Q000528:radiation effects; D020552:Comet Assay; D004249:DNA Damage / Q000187:drug effects; D005516:Food Microbiology; D008027:Light; D008089:Listeria monocytogenes / Q000528:radiation effects*; D013211:Staphylococcus aureus / Q000528:radiation effects*
keywords: 405nm light emitting diode; DNA damage; Gram-positive foodborne pathogens; Membrane permeability; Photodynamic inactivation