Fundamental Characteristics of Deep-UV Light-Emitting Diodes and Their Application To Control Foodborne Pathogens

ABSTRACTLow-pressure mercury UV (LP-UV) lamps have long been used for bacterial inactivation, but due to certain disadvantages, such as the possibility of mercury leakage, deep-UV-C light-emitting diodes (DUV-LEDs) for disinfection have recently been of great interest as an alternative. Therefore, in this study, we examined the basic spectral properties of DUV-LEDs and the effects of UV-C irradiation for inactivating foodborne pathogens, includingEscherichia coliO157:H7,Salmonella entericaserovar Typhimurium, andListeria monocytogenes, on solid media, as well as in water. As the temperature increased, DUV-LED light intensity decreased slightly, whereas LP-UV lamps showed increasing intensity until they reached a peak at around 30°C. As the irradiation dosage and temperature increased,E. coliO157:H7 andS. Typhimurium experienced 5- to 6-log-unit reductions.L. monocytogeneswas reduced by over 5 log units at a dose of 1.67 mJ/cm2. At 90% relative humidity (RH), onlyE. coliO157:H7 experienced inactivation significantly greater than at 30 and 60% RH. In a water treatment study involving a continuous system, 6.38-, 5.81-, and 3.47-log-unit reductions were achieved inE. coliO157:H7,S. Typhimurium, andL. monocytogenes, respectively, at 0.5 liter per minute (LPM) and 200 mW output power. The results of this study suggest that the use of DUV-LEDs may compensate for the drawbacks of using LP-UV lamps to inactivate foodborne pathogens.

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Using UVC Light-Emitting Diodes at Wavelengths of 266 to 279 Nanometers To Inactivate Foodborne Pathogens and Pasteurize Sliced Cheese

Applied and Environmental Microbiology ◽

10.1128/aem.02092-15 ◽

2015 ◽

Vol 82 (1) ◽

pp. 11-17 ◽

Cited By ~ 41

Author(s):

Soo-Ji Kim ◽

Do-Kyun Kim ◽

Dong-Hyun Kang

Keyword(s):

Foodborne Pathogens ◽

Light Emitting Diodes ◽

Uv Light ◽

Content Type ◽

Warm Up ◽

Light Emitting ◽

Uv Led ◽

Serovar Typhimurium ◽

Uv Lamps ◽

Uv Leds

ABSTRACTUVC light is a widely used sterilization technology. However, UV lamps have several limitations, including low activity at refrigeration temperatures, a long warm-up time, and risk of mercury exposure. UV-type lamps only emit light at 254 nm, so as an alternative, UV light-emitting diodes (UV-LEDs) which can produce the desired wavelengths have been developed. In this study, we validated the inactivation efficacy of UV-LEDs by wavelength and compared the results to those of conventional UV lamps. Selective media inoculated withEscherichia coliO157:H7,Salmonella entericaserovar Typhimurium, andListeria monocytogeneswere irradiated using UV-LEDs at 266, 270, 275, and 279 nm in the UVC spectrum at 0.1, 0.2, 0.5, and 0.7 mJ/cm2, respectively. The radiation intensity of the UV-LEDs was about 4 μW/cm2, and UV lamps were covered with polypropylene films to adjust the light intensity similar to those of UV-LEDs. In addition, we applied UV-LED to sliced cheese at doses of 1, 2, and 3 mJ/cm2. Our results showed that inactivation rates after UV-LED treatment were significantly different (P< 0.05) from those of UV lamps at a similar intensity. On microbiological media, UV-LED treatments at 266 and 270 nm showed significantly different (P< 0.05) inactivation effects than other wavelength modules. For sliced cheeses, 4- to 5-log reductions occurred after treatment at 3 mJ/cm2for all three pathogens, with negligible generation of injured cells.

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Performance of vertical type deep UV light-emitting diodes depending on the Ga-face n-contact hole density

Applied Physics Letters ◽

10.1063/5.0052416 ◽

2021 ◽

Vol 118 (23) ◽

pp. 231102

Author(s):

Youn Joon Sung ◽

Dong-Woo Kim ◽

Geun Young Yeom ◽

Kyu Sang Kim

Keyword(s):

Light Emitting Diodes ◽

Uv Light ◽

Hole Density ◽

Light Emitting ◽

Deep Uv

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Robust 285 nm Deep UV Light Emitting Diodes over Metal Organic Hydride Vapor Phase Epitaxially Grown AlN/Sapphire Templates

Japanese Journal of Applied Physics ◽

10.1143/jjap.46.l537 ◽

2007 ◽

Vol 46 (No. 23) ◽

pp. L537-L539 ◽

Cited By ~ 26

Author(s):

Vinod Adivarahan ◽

Qhalid Fareed ◽

Surendra Srivastava ◽

Thomas Katona ◽

Mikhail Gaevski ◽

...

Keyword(s):

Vapor Phase ◽

Light Emitting Diodes ◽

Uv Light ◽

Light Emitting ◽

Organic Hydride ◽

Metal Organic ◽

Deep Uv

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Selection for Antimicrobial Resistance in Foodborne Pathogens through Exposure to UV Light and Nonthermal Atmospheric Plasma Decontamination Techniques

Applied and Environmental Microbiology ◽

10.1128/aem.00102-20 ◽

2020 ◽

Vol 86 (9) ◽

Author(s):

Adrián Álvarez-Molina ◽

María de Toro ◽

Lorena Ruiz ◽

Mercedes López ◽

Miguel Prieto ◽

...

Keyword(s):

Foodborne Pathogens ◽

Uv Light ◽

Brain Heart Infusion ◽

Atmospheric Plasma ◽

Cross Resistance ◽

Whole Genome ◽

Whole Genome Analysis ◽

Resistant Variant ◽

Content Type ◽

Uv C

ABSTRACT This study was aimed at assessing whether the repeated exposure of 12 strains of Salmonella spp., Escherichia coli, and Listeria monocytogenes to alternative nonthermal decontamination techniques with UV light (UV-C) and nonthermal atmospheric plasma (NTAP) may cause the emergence of variants showing increased resistance to clinically relevant antibiotics (ampicillin, cefotaxime, ciprofloxacin, gentamicin, streptomycin, tetracycline, erythromycin, vancomycin, and colistin). UV-C and NTAP treatments were applied on the surface of inoculated brain heart infusion (BHI) agar plates. Survivors were recovered and after 24 h of growth in BHI broth were again subjected to the decontamination treatment; this was repeated for 10 consecutive cycles. A total of 174 strain/decontamination technique/antibiotic combinations were tested, and 12 variant strains with increased resistance to one of the antibiotics studied were identified, with the increases in the MICs in Mueller-Hinton broth ranging from 2- to 256-fold. The variant strains of Salmonella spp. isolated were further characterized through phenotypic screenings and whole-genome sequencing (WGS) analyses. Most changes in susceptibility were observed for antibiotics that act at the level of protein synthesis (aminoglycosides, tetracyclines, and glycylcyclines) or DNA replication (fluoroquinolones), as well as for polymyxins. No changes in resistance to β-lactams were detected. WGS analyses showed the occurrence of sequence alterations in some antibiotic cellular targets (e.g., gyrA for ciprofloxacin-resistant variants, rpsL for a streptomycin-resistant variant), accompanied by variations in stress response regulators and membrane transporters likely involved in the nonselective efflux of antibiotics, which altogether resulted in a low- to medium-level increase in microbial resistance to several antibiotics. IMPORTANCE The emergence and spread of antibiotic resistance along the food chain can be influenced by the different antimicrobial strategies used from farm to fork. This study evidences that two novel, not yet widely used, nonthermal microbial decontamination techniques, UV light and nonthermal atmospheric plasma, can select variants with increased resistance to various clinically relevant antibiotics, such as ciprofloxacin, streptomycin, tetracycline, and erythromycin. Whole-genome analysis of the resistant variants obtained for Salmonella spp. allowed identification of the genetic changes responsible for the observed phenotypes and suggested that some antimicrobial classes are more susceptible to the cross-resistance phenomena observed. This information is relevant, since these novel decontamination techniques are being proposed as possible alternative green techniques for the decontamination of environments and equipment in food and clinical settings.

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