Comparison of the inactivation of seven foodborne pathogens and spoilage bacteria under 405 nm blue light treatment in liquid media and on solid surfaces

ABSTRACT Antimicrobial blue light (aBL; 405 nm) can reduce the viability of multiple bacteria, but there are few reports comparing the susceptibility of foodborne bacteria when exposed to similar conditions. This study was undertaken to evaluate the efficacy of aBL against foodborne pathogens and sp...

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Main Authors: Minji Hur, Francisco Diez-Gonzalez
Format: Article
Language:English
Published: American Society for Microbiology 2025-07-01
Series:Microbiology Spectrum
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Online Access:https://journals.asm.org/doi/10.1128/spectrum.00093-25
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author Minji Hur
Francisco Diez-Gonzalez
author_facet Minji Hur
Francisco Diez-Gonzalez
author_sort Minji Hur
collection DOAJ
description ABSTRACT Antimicrobial blue light (aBL; 405 nm) can reduce the viability of multiple bacteria, but there are few reports comparing the susceptibility of foodborne bacteria when exposed to similar conditions. This study was undertaken to evaluate the efficacy of aBL against foodborne pathogens and spoilage bacteria when treated in liquid media and on different surfaces. Cocktails of Listeria, Salmonella, Escherichia, Pseudomonas, Cronobacter, Lactobacillus, and Staphylococcus were incubated in tryptic soy broth (TSB) and phosphate-buffered saline (PBS), as well as on stainless steel (SS) coupons, avocados, and cherry tomatoes as dried cells. Reductions in cell viability were determined after exposure to 405 nm aBL at two temperatures. aBL doses for liquid, SS coupons, and fruits were 1,512, 1,739, and 1,944 J/cm2, respectively. Microbiological counts were determined using standard complex media, and Analysis of variance (ANOVA) was used to determine significant differences (P < 0.05). The viability of Pseudomonas in PBS was reduced by more than 8 Log CFU/mL of aBL exposure, but the reduction of other bacteria was less than 4 Log CFU/mL. In TSB, more than 5 Log CFU/mL were inactivated in all genera. Reductions in viable Cronobacter and Salmonella dried cells on SS coupons were less than 2 Log CFU/coupon. Treatment of cells on avocados resulted in small reductions of Cronobacter and Salmonella (<1.5 Log CFU/skin spot) at 20°C compared to other species. These findings suggest that the susceptibility of different bacterial genera may be quite variable in response to aBL treatment, and these differences should be considered for potential applications.IMPORTANCEReady-to-eat (RTE) foods have been associated with multiple outbreaks caused by foodborne pathogens. While the safety of many RTE foods such as fresh produce relies on traditional cleaning and sanitation systems, they are often insufficient to keep bacteria off food-contact surfaces within the processing and packing environment. Antimicrobial blue light (aBL) in the range of 400–470 nm of wavelength may be a promising disinfectant alternative. However, more comprehensive studies are needed to better assess the effectiveness of aBL against a wide range of foodborne pathogens and spoilage. Such research could provide valuable insights into aBL’s potential as a crucial tool for ensuring food safety.
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spelling doaj-art-a937e5378ca94a60916330e44ad813192025-08-20T03:30:55ZengAmerican Society for MicrobiologyMicrobiology Spectrum2165-04972025-07-0113710.1128/spectrum.00093-25Comparison of the inactivation of seven foodborne pathogens and spoilage bacteria under 405 nm blue light treatment in liquid media and on solid surfacesMinji Hur0Francisco Diez-Gonzalez1Center for Food Safety and Department of Food Science and Technology, University of Georgia, Griffin, Georgia, USACenter for Food Safety and Department of Food Science and Technology, University of Georgia, Griffin, Georgia, USAABSTRACT Antimicrobial blue light (aBL; 405 nm) can reduce the viability of multiple bacteria, but there are few reports comparing the susceptibility of foodborne bacteria when exposed to similar conditions. This study was undertaken to evaluate the efficacy of aBL against foodborne pathogens and spoilage bacteria when treated in liquid media and on different surfaces. Cocktails of Listeria, Salmonella, Escherichia, Pseudomonas, Cronobacter, Lactobacillus, and Staphylococcus were incubated in tryptic soy broth (TSB) and phosphate-buffered saline (PBS), as well as on stainless steel (SS) coupons, avocados, and cherry tomatoes as dried cells. Reductions in cell viability were determined after exposure to 405 nm aBL at two temperatures. aBL doses for liquid, SS coupons, and fruits were 1,512, 1,739, and 1,944 J/cm2, respectively. Microbiological counts were determined using standard complex media, and Analysis of variance (ANOVA) was used to determine significant differences (P < 0.05). The viability of Pseudomonas in PBS was reduced by more than 8 Log CFU/mL of aBL exposure, but the reduction of other bacteria was less than 4 Log CFU/mL. In TSB, more than 5 Log CFU/mL were inactivated in all genera. Reductions in viable Cronobacter and Salmonella dried cells on SS coupons were less than 2 Log CFU/coupon. Treatment of cells on avocados resulted in small reductions of Cronobacter and Salmonella (<1.5 Log CFU/skin spot) at 20°C compared to other species. These findings suggest that the susceptibility of different bacterial genera may be quite variable in response to aBL treatment, and these differences should be considered for potential applications.IMPORTANCEReady-to-eat (RTE) foods have been associated with multiple outbreaks caused by foodborne pathogens. While the safety of many RTE foods such as fresh produce relies on traditional cleaning and sanitation systems, they are often insufficient to keep bacteria off food-contact surfaces within the processing and packing environment. Antimicrobial blue light (aBL) in the range of 400–470 nm of wavelength may be a promising disinfectant alternative. However, more comprehensive studies are needed to better assess the effectiveness of aBL against a wide range of foodborne pathogens and spoilage. Such research could provide valuable insights into aBL’s potential as a crucial tool for ensuring food safety.https://journals.asm.org/doi/10.1128/spectrum.00093-25blue lightfoodborne pathogensfood safetyLactobacillusPseudomonas
spellingShingle Minji Hur
Francisco Diez-Gonzalez
Comparison of the inactivation of seven foodborne pathogens and spoilage bacteria under 405 nm blue light treatment in liquid media and on solid surfaces
Microbiology Spectrum
blue light
foodborne pathogens
food safety
Lactobacillus
Pseudomonas
title Comparison of the inactivation of seven foodborne pathogens and spoilage bacteria under 405 nm blue light treatment in liquid media and on solid surfaces
title_full Comparison of the inactivation of seven foodborne pathogens and spoilage bacteria under 405 nm blue light treatment in liquid media and on solid surfaces
title_fullStr Comparison of the inactivation of seven foodborne pathogens and spoilage bacteria under 405 nm blue light treatment in liquid media and on solid surfaces
title_full_unstemmed Comparison of the inactivation of seven foodborne pathogens and spoilage bacteria under 405 nm blue light treatment in liquid media and on solid surfaces
title_short Comparison of the inactivation of seven foodborne pathogens and spoilage bacteria under 405 nm blue light treatment in liquid media and on solid surfaces
title_sort comparison of the inactivation of seven foodborne pathogens and spoilage bacteria under 405 nm blue light treatment in liquid media and on solid surfaces
topic blue light
foodborne pathogens
food safety
Lactobacillus
Pseudomonas
url https://journals.asm.org/doi/10.1128/spectrum.00093-25
work_keys_str_mv AT minjihur comparisonoftheinactivationofsevenfoodbornepathogensandspoilagebacteriaunder405nmbluelighttreatmentinliquidmediaandonsolidsurfaces
AT franciscodiezgonzalez comparisonoftheinactivationofsevenfoodbornepathogensandspoilagebacteriaunder405nmbluelighttreatmentinliquidmediaandonsolidsurfaces