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Acosta RB, Durantini EN, Spesia MB. Evaluation of quantification methods to determine photodynamic action on mono- and dual-species bacterial biofilms. Photochem Photobiol Sci 2024; 23:1195-1208. [PMID: 38703274 DOI: 10.1007/s43630-024-00586-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2024] [Accepted: 04/23/2024] [Indexed: 05/06/2024]
Abstract
The effect of photodynamic inactivation (PDI) sensitized by 5,10,15,20-tetra(4-N,N,N-trimethylammoniophenyl)porphyrin (TMAP4+) on different components of mono- and dual-species biofilms of Staphylococcus aureus and Escherichia coli was determined by different methods. First, the plate count technique showed that TMAP4+-PDI was more effective on S. aureus than E. coli biofilm. However, crystal violet staining revealed no significant differences between before and after PDI biofilms of both bacteria. On the other hand, the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide method indicated a reduction in viable cells as the light exposure time increases in both, mono- and dual-species biofilms. Furthermore, it was determined that as the irradiation time increases, the amount of extracellular polymeric substances present in the biofilms decreased. This effect was presented in both strains and in the mixed biofilm, being more evident in S. aureus mono-specie biofilm. Finally, scanning electron microscopy analysis showed a decrease in the number of cells forming the biofilm after photosensitization treatments. This information makes it possible to determine whether the photodynamic action is based on damage to metabolic activity, extracellular matrix and/or biomass, which may be useful in establishing a fully effective PDI protocol for the treatment of microorganisms growing as biofilms.
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Affiliation(s)
- Rocío B Acosta
- IDAS-CONICET, Departamento de Química, Facultad de Ciencias Exactas, Físico-Químicas y Naturales, Universidad Nacional de Río Cuarto, Ruta Nacional 36 Km 601, X5804BYA, Río Cuarto, Córdoba, Argentina
| | - Edgardo N Durantini
- IDAS-CONICET, Departamento de Química, Facultad de Ciencias Exactas, Físico-Químicas y Naturales, Universidad Nacional de Río Cuarto, Ruta Nacional 36 Km 601, X5804BYA, Río Cuarto, Córdoba, Argentina
| | - Mariana B Spesia
- IDAS-CONICET, Departamento de Química, Facultad de Ciencias Exactas, Físico-Químicas y Naturales, Universidad Nacional de Río Cuarto, Ruta Nacional 36 Km 601, X5804BYA, Río Cuarto, Córdoba, Argentina.
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Prasad A, Wynands E, Roche SM, Romo-Bernal C, Allan N, Olson M, Levengood S, Andersen R, Loebel N, Sabino CP, Ross JA. Photodynamic Inactivation of Foodborne Bacteria: Screening of 32 Potential Photosensitizers. Foods 2024; 13:453. [PMID: 38338588 PMCID: PMC10855769 DOI: 10.3390/foods13030453] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2023] [Revised: 01/22/2024] [Accepted: 01/29/2024] [Indexed: 02/12/2024] Open
Abstract
The development of novel antimicrobial technologies for the food industry represents an important strategy to improve food safety. Antimicrobial photodynamic disinfection (aPDD) is a method that can inactivate microbes without the use of harsh chemicals. aPDD involves the administration of a non-toxic, light-sensitive substance, known as a photosensitizer, followed by exposure to visible light at a specific wavelength. The objective of this study was to screen the antimicrobial photodynamic efficacy of 32 food-safe pigments tested as candidate photosensitizers (PSs) against pathogenic and food-spoilage bacterial suspensions as well as biofilms grown on relevant food contact surfaces. This screening evaluated the minimum bactericidal concentration (MBC), minimum biofilm eradication concentration (MBEC), and colony forming unit (CFU) reduction against Salmonella enterica, methicillin-resistant Staphylococcus aureus (MRSA), Pseudomonas fragi, and Brochothrix thermosphacta. Based on multiple characteristics, including solubility and the ability to reduce the biofilms by at least 3 log10 CFU/sample, 4 out of the 32 PSs were selected for further optimization against S. enterica and MRSA, including sunset yellow, curcumin, riboflavin-5'-phosphate (R-5-P), and erythrosin B. Optimized factors included the PS concentration, irradiance, and time of light exposure. Finally, 0.1% w/v R-5-P, irradiated with a 445 nm LED at 55.5 J/cm2, yielded a "max kill" (upwards of 3 to 7 log10 CFU/sample) against S. enterica and MRSA biofilms grown on metallic food contact surfaces, proving its potential for industrial applications. Overall, the aPDD method shows substantial promise as an alternative to existing disinfection technologies used in the food processing industry.
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Affiliation(s)
- Amritha Prasad
- Chinook Contract Research Inc., Airdrie, AB T4A 0C3, Canada; (A.P.); (N.A.); (M.O.)
| | - Erin Wynands
- ACER Consulting, Guelph, ON N1G 5L3, Canada; (E.W.); (S.M.R.)
| | - Steven M. Roche
- ACER Consulting, Guelph, ON N1G 5L3, Canada; (E.W.); (S.M.R.)
| | - Cristina Romo-Bernal
- Ondine Biomedical Inc., Bothell, WA 98011, USA; (C.R.-B.); (S.L.); (R.A.); (N.L.); (C.P.S.)
| | - Nicholas Allan
- Chinook Contract Research Inc., Airdrie, AB T4A 0C3, Canada; (A.P.); (N.A.); (M.O.)
| | - Merle Olson
- Chinook Contract Research Inc., Airdrie, AB T4A 0C3, Canada; (A.P.); (N.A.); (M.O.)
| | - Sheeny Levengood
- Ondine Biomedical Inc., Bothell, WA 98011, USA; (C.R.-B.); (S.L.); (R.A.); (N.L.); (C.P.S.)
| | - Roger Andersen
- Ondine Biomedical Inc., Bothell, WA 98011, USA; (C.R.-B.); (S.L.); (R.A.); (N.L.); (C.P.S.)
| | - Nicolas Loebel
- Ondine Biomedical Inc., Bothell, WA 98011, USA; (C.R.-B.); (S.L.); (R.A.); (N.L.); (C.P.S.)
| | - Caetano P. Sabino
- Ondine Biomedical Inc., Bothell, WA 98011, USA; (C.R.-B.); (S.L.); (R.A.); (N.L.); (C.P.S.)
- Center for Lasers and Applications, Energy and Nuclear Research Institute, São Paulo 05508-000, SP, Brazil
| | - Joseph A. Ross
- Chinook Contract Research Inc., Airdrie, AB T4A 0C3, Canada; (A.P.); (N.A.); (M.O.)
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