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Angela S, Lleò MM, Bontempi P, Boschi F. A New Method to Easily Assess Bacteriostatic and Bactericidal Activity of Ultraviolet Radiation Using Quantitative Image Analysis. Photochem Photobiol 2023; 99:1476-1482. [PMID: 36825386 DOI: 10.1111/php.13796] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2022] [Accepted: 02/21/2023] [Indexed: 02/25/2023]
Abstract
Ultraviolet (UV) radiation can elicit both bactericidal and bacteriostatic activity depending on light parameters and targeted bacteria. Current methods based on bacterial growth on solid medium allow measurement of only bactericidal but not bacteriostatic activity, while liquid cultures exhibit low light penetration. Here, we propose a method to quantify both bactericidal and bacteriostatic activity of radiation based on (a) bacterial cultures on solid medium, (b) acquisition and quantitative analysis of photographic images of plates containing bacterial colonies, (c) application of two mathematical equations to evaluate bactericidal and bacteriostatic activity. The proposed method considers the differences in growth on test and control (unexposed) plates. The measurements performed on the plates image are the independent variables of the mathematical equations returning the values of bactericidal and bacteriostatic activity. Experimentally, a test was performed using Escherichia coli grown on a solid medium and exposed to UVA (365 nm) radiation. The standard method allowed quantifying bactericidal activity and evaluating only qualitatively bacteriostatic activity of the radiation. Differently, the new method here proposed allowed quantification of both activities. The proposed method proved to be simple, enabling deep assessment of the antibacterial effects of UV radiation directly on the solid medium through image acquisition and analysis.
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Affiliation(s)
- Sandri Angela
- Department of Diagnostics and Public Health, Microbiology Section, University of Verona, Verona, Italy
| | - Maria M Lleò
- Department of Diagnostics and Public Health, Microbiology Section, University of Verona, Verona, Italy
| | - Pietro Bontempi
- Department of Computer Science, University of Verona, Verona, Italy
| | - Federico Boschi
- Department of Computer Science, University of Verona, Verona, Italy
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Sandri A, Tessari A, Giannetti D, Cetti A, Lleo MM, Boschi F. UV-A Radiation: Safe Human Exposure and Antibacterial Activity. Int J Mol Sci 2023; 24:ijms24098331. [PMID: 37176038 PMCID: PMC10179708 DOI: 10.3390/ijms24098331] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2023] [Revised: 05/02/2023] [Accepted: 05/04/2023] [Indexed: 05/15/2023] Open
Abstract
UV radiation is used for sterilization but has adverse health effects in humans. UV-A radiation has lower antimicrobial effect than UV-B and UV-C but constitutes a lower health risk, opening up the possibility to sanitize environments with human presence in controlled exposure conditions. We investigated this possibility by identifying safe exposure conditions to a UV-A lamp along with efficient sanitization of the environment. The human exposure limits were calculated following the guidelines provided by the International Commission on Non-Ionizing Radiation Protection and the International Commission on Illumination. Antibacterial activity was evaluated on Escherichia coli, Pseudomonas aeruginosa and Staphylococcus aureus. The maximum human exposure duration has been identified at different irradiation distance and angle, increasing with the increase of both parameters. Bactericidal activity was observed in all microorganisms and was higher with higher exposure time and at lower distance from the source. Noteworthily, in equal conditions of radiant exposure, the exposure time impacts on the bactericidal activity more than the distance from the source. The modulation of factors such as distance from the source, exposure time and irradiation angle can enable effective antibacterial activity and human safety. Prolonged direct irradiation of the surfaces associated with indirect human exposure represents the condition of greater efficacy and safety.
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Affiliation(s)
- Angela Sandri
- Department of Diagnostics and Public Health, University of Verona, Strada Le Grazie 8, 37134 Verona, Italy
| | - Aldo Tessari
- FOR ALL Srl, Via 8 Marzo 10-12, Bussolengo, 37012 Verona, Italy
| | | | - Alberto Cetti
- FOR ALL Srl, Via 8 Marzo 10-12, Bussolengo, 37012 Verona, Italy
| | - Maria M Lleo
- Department of Diagnostics and Public Health, University of Verona, Strada Le Grazie 8, 37134 Verona, Italy
| | - Federico Boschi
- Department of Engineering for Innovation Medicine, University of Verona, Strada Le Grazie 8, 37134 Verona, Italy
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Kang JW, Hong HN, Kang DH. Application of a Krypton-Chlorine Excilamp To Control Alicyclobacillus acidoterrestris Spores in Apple Juice and Identification of Its Sporicidal Mechanism. Appl Environ Microbiol 2020; 86:e00159-20. [PMID: 32220842 PMCID: PMC7237776 DOI: 10.1128/aem.00159-20] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2020] [Accepted: 03/23/2020] [Indexed: 12/18/2022] Open
Abstract
The aim of this study was to investigate the sporicidal effect of a krypton-chlorine (KrCl) excilamp against Alicyclobacillus acidoterrestris spores and to compare its inactivation mechanism to that of a conventional UV lamp containing mercury (Hg). The inactivation effect of the KrCl excilamp was not significantly different from that of the Hg UV lamp for A. acidoterrestris spores in apple juice despite the 222-nm wavelength of the KrCl excilamp having a higher absorption coefficient in apple juice than the 254-nm wavelength of the Hg UV lamp; this is because KrCl excilamps have a fundamentally greater inactivation effect than Hg UV lamps, which is confirmed under ideal conditions (phosphate-buffered saline). The inactivation mechanism analysis revealed that the DNA damage induced by the KrCl excilamp was not significantly different (P > 0.05) from that induced by the Hg UV lamp, while the KrCl excilamp caused significantly higher (P < 0.05) lipid peroxidation incidence and permeability change in the inner membrane of A. acidoterrestris spores than did the Hg UV lamp. Meanwhile, the KrCl excilamp did not generate significant (P > 0.05) intracellular reactive oxygen species, indicating that the KrCl excilamp causes damage only through the direct absorption of UV light. In addition, after KrCl excilamp treatment with a dose of 2,011 mJ/cm2 to reduce A. acidoterrestris spores in apple juice by 5 logs, there were no significant (P > 0.05) changes in quality parameters such as color (L*, a*, and b*), total phenolic compounds, and DPPH (2,2-diphenyl-1-picrylhydrazyl) free radical scavenging activity.IMPORTANCEAlicyclobacillus acidoterrestris spores, which have high resistance to thermal treatment and can germinate even at low pH, are very troublesome in the juice industry. UV technology, a nonthermal treatment, can be an excellent means to control heat-resistant A. acidoterrestris spores in place of thermal treatment. However, the traditionally applied UV sources are lamps that contain mercury (Hg), which is harmful to humans and the environment; thus, there is a need to apply novel UV technology without the use of Hg. In response to this issue, excilamps, an Hg-free UV source, have been actively studied. However, no studies have been conducted applying this technique to control A. acidoterrestris spores. Therefore, the results of this study, which applied a KrCl excilamp for the control of A. acidoterrestris spores and elucidated the inactivation principle, are expected to be utilized as important basic data for application to actual industry or conducting further studies.
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Affiliation(s)
- Jun-Won Kang
- Department of Food and Animal Biotechnology, Department of Agricultural Biotechnology, Center for Food and Bioconvergence, and Research Institute for Agricultural and Life Sciences, Seoul National University, Seoul, Republic of Korea
| | - Hak-Nyeong Hong
- Department of Food and Animal Biotechnology, Department of Agricultural Biotechnology, Center for Food and Bioconvergence, and Research Institute for Agricultural and Life Sciences, Seoul National University, Seoul, Republic of Korea
| | - Dong-Hyun Kang
- Department of Food and Animal Biotechnology, Department of Agricultural Biotechnology, Center for Food and Bioconvergence, and Research Institute for Agricultural and Life Sciences, Seoul National University, Seoul, Republic of Korea
- Institutes of Green Bio Science and Technology, Seoul National University, Pyeongchang-gun, Gangwon-do, Republic of Korea
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Light, Electromagnetic Spectrum, and Photostimulation of Microorganisms with Special Reference to Chaetomium. Fungal Biol 2020. [DOI: 10.1007/978-3-030-31612-9_14] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Kim S, Kim J, Lim W, Jeon S, Kim O, Koh JT, Kim CS, Choi H, Kim O. In vitro bactericidal effects of 625, 525, and 425 nm wavelength (red, green, and blue) light-emitting diode irradiation. Photomed Laser Surg 2013; 31:554-62. [PMID: 24138193 DOI: 10.1089/pho.2012.3343] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
OBJECTIVE The purpose of this study was to evaluate the relationship of 625, 525, and 425 nm wavelengths, providing average power output and effects on three common pathogenic bacteria. BACKGROUND DATA Ultraviolet (UV) light kills bacteria, but the bactericidal effects of UV may not be unique, as 425 nm produces a similar effect. The bactericidal effects of light-emitting diode (LED) wavelengths such as 625 and 525 nm have not been described. Before conducting clinical trials, the appropriate wavelength with reasonable dose and exposure time should be established. MATERIALS AND METHODS The bactericidal effects of 625, 525, and 425 nm wavelength LED irradiation were investigated in vitro for the anaerobic bacterium Porphyromonas gingivalis and two aerobes (Staphylococcus aureus and Escherichia coli DH5α). Average power output was 6 mW/cm(2) for 1 h. The bacteria were exposed to LED irradiation for 1, 2, 4, and 8 h (21.6, 43.2, 86.4, and 172.8 J/cm(2), respectively). LED irradiation was performed during growth on agar and in broth. Control bacteria were incubated without LED irradiation. Bacterial growth was expressed in colony-forming units (CFU) and at an optical density at 600 nm in agar and broth. RESULTS The bactericidal effect of LED phototherapy depended upon wavelength, power density, bacterial viable number, and bacteria species. The bactericidal effect of 425 and 525 nm irradiation varied depending upon the bacterial inoculation, compared with unirradiated samples and samples irradiated with red light. Especially, P. gingivalis and E. coli DH5α were killed by 425 nm, and S. aureus growth was inhibited by 525 nm. However, the wavelength of 625 nm was not bactericidal for P. gingivalis, E. coli DH5α, or S. aureus. CONCLUSIONS Irradiation at 625 nm light was not bactericidal to S. aureus, E. coli, and P. gingivalis, whereas wavelengths of 425 and 525 nm had bactericidal effects. S. aureus was also killed at 525 nm.
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Affiliation(s)
- SangWoo Kim
- 1 Department of Oral Pathology, Medical Research Center for Biomineralization Disorders, School of Dentistry, Dental Science Research Institute, Chonnam National University , Bug-Gu, Gwangju, Republic of Korea
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Maktabi S, Watson I, Parton R. Synergistic effect of UV, laser and microwave radiation or conventional heating on E. coli and on some spoilage and pathogenic bacteria. INNOV FOOD SCI EMERG 2011. [DOI: 10.1016/j.ifset.2010.12.011] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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Zerdin K, Scully AD. Inactivation of food-borne spoilage and pathogenic micro-organisms on the surface of a photoactive polymer. Photochem Photobiol 2010; 86:1109-17. [PMID: 20670362 DOI: 10.1111/j.1751-1097.2010.00774.x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The photodynamic action of a novel photoactive polymer comprising covalently bound anthraquinone (AQ) moieties was evaluated after developing a methodology to reliably immobilize viable micro-organisms onto polymer film surfaces. The survival of Escherichia coli, Bacillus cereus (vegetative cells and spores), Fusarium oxysporum and Saccharomyces cerevisiae microbes inoculated on the surface of inert polymeric substrates was assessed to determine the effect of inoculum composition, drying rate and exposure to ultraviolet (UV-A) radiation. Their survival was highly dependent on microbial genus, with E. coli consistently displaying markedly shorter survival times than the other microbes, and B. cereus spores being the most resistant. Inoculation of the microbes onto the surface of the photoactive polymer films, followed by exposure to UV-A radiation, dramatically accelerated the inactivation of all microbial types studied compared with their survival on the surface of inert polymer substrates. Simultaneous exposure to both oxygen and UV-A radiation is required to affect cell survival, which is consistent with this effect most likely originating from the photoinduced production of singlet oxygen by the photoactive polymer. These results provide further compelling evidence that singlet oxygen produced exogenously by this photoactive polymeric substrate can successfully inactivate a broad spectrum of microbes on the substrate's surface.
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BELTRÁN F, PÉREZ-LÓPEZ A, LÓPEZ-NICOLÁS J, CARBONELL-BARRACHINA A. COLOR AND VITAMIN C CONTENT IN MANDARIN ORANGE JUICE AS AFFECTED BY PACKAGING MATERIAL AND STORAGE TEMPERATURE. J FOOD PROCESS PRES 2009. [DOI: 10.1111/j.1745-4549.2008.00247.x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Koutchma T. Advances in Ultraviolet Light Technology for Non-thermal Processing of Liquid Foods. FOOD BIOPROCESS TECH 2009. [DOI: 10.1007/s11947-008-0178-3] [Citation(s) in RCA: 207] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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Xie Y, Hajdok C, Mittal GS, Warriner K. Inactivation of MS2 F(+) coliphage on lettuce by a combination of UV light and hydrogen peroxide. J Food Prot 2008; 71:903-7. [PMID: 18522021 DOI: 10.4315/0362-028x-71.5.903] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
The efficacy of a produce decontamination method based on a combination of UV light (254 nm) and hydrogen peroxide (H2O2) to inactivate the MS2 F(+) coliphage inoculated onto iceberg lettuce was evaluated. Lettuce inoculated with 6.57 log PFU of MS2 was reduced by 0.5 to 1.0 log unit when illuminated with UV light alone for 20 to 60 s (12.64 to 18.96 mJ/cm2). In contrast, a 3-log reduction in MS2 was achieved with 2% (vol/vol) H2O2 spray delivered at 50 degrees C. No significant increase in log count reduction (LCR) was observed when H2O2 and UV light were applied simultaneously. However, H2O2 sprayed onto lettuce samples for 10 s, followed by a further 20-s UV illumination, resulted in an LCR of 4.12 that compares with the 1.67 obtained with 200 ppm of calcium hypochlorite wash. No further increase in MS2 inactivation was achieved by the use of either longer H2O2 spray or UV illumination times. The extent of MS2 reduction was significantly (P < 0.05) decreased when the H2O2 spray was delivered at 10 or 25 degrees C compared with 50 degrees C. In the course of aerobic storage at 4 degrees C, lettuce treated with UV light and H2O2 (10 or 25 degrees C) developed discoloration (polyphenol accumulation) within 6 days. In contrast, lettuce treated with UV light and H2O2 at 50 degrees C developed less discoloration within this time period and was comparable to untreated controls. This study demonstrated that the combination of UV light and H2O2 represents an alternative to hypochlorite-based washes to reduce the carriage of viruses on fresh produce.
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Affiliation(s)
- Y Xie
- Department of Food Science, University of Guelph, Guelph, Ontario, Canada
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. BO. Fungi/Bactericidal and Static Effects of Ultraviolet Light in 254 and 354 nm Wavelengths. ACTA ACUST UNITED AC 2007. [DOI: 10.3923/jm.2007.42.49] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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Warriner K, Kolstad J, Rumsby P, Waites WM. Carton sterilization by u.v.-C excimer laser light: recovery of Bacillus subtilis spores on vegetable extracts and food simulation matrices. J Appl Microbiol 2002; 92:1051-7. [PMID: 12010545 DOI: 10.1046/j.1365-2672.2002.01641.x] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
AIMS To determine the recovery of Bacillus subtilis spores loaded onto preformed cartons and irradiated with u.v.-excimer laser (248 nm) light. METHODS AND RESULTS Bacillus subtilis spores irradiated with u.v.-excimer laser light retained phase brightness, but were blocked at various stages of germination. In the presence of germinant, the majority of spores began to lose phase brightness but only after an extended lag period (ca 90 min). After 6 h ca 9% of the spores had elongated but failed to form new cells, approx. 12% had undergone partial phase darkening (grey spores), 15% remained phase bright whilst the remainder had turned fully phase dark but failed to elongate. No enhanced recovery of u.v.-treated spores (with intact or permeabilized coats) occurred in media containing hen egg white lysozyme or vegetable extracts (celery, carrot, swede or turnip). However, recovery did occur when irradiated spores were incubated for 26 d, semiaerobically, within cartons containing nutrient broth or milk. CONCLUSIONS The germination ability of B. subtilis spores is altered following u.v.-excimer laser treatment. Recovery of treated spores was found in liquid systems but not on agar plates supplemented with vegetable extracts or lysozyme. SIGNIFICANCE AND IMPACT OF THE STUDY The potential recovery of u.v.-excimer laser-treated spores in a range of carton-packed food systems requires further investigation.
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Affiliation(s)
- K Warriner
- Division of Food Sciences, School of Biosciences, University of Nottingham, Sutton Bonington, Loughborough, Leicestershire, UK
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