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Sporicidal performance induced by photocatalytic production of organic peroxide under visible light irradiation

View Article: PubMed Central - PubMed

ABSTRACT

Bacteria that cause serious food poisoning are known to sporulate under conditions of nutrient and water shortage. The resulting spores have much greater resistance to common sterilization methods, such as heating at 100 °C and exposure to various chemical agents. Because such bacteria cannot be inactivated with typical alcohol disinfectants, peroxyacetic acid (PAA) often is used, but PAA is a harmful agent that can seriously damage human health. Furthermore, concentrated hydrogen peroxide, which is also dangerous, must be used to prepare PAA. Thus, the development of a facile and safe sporicidal disinfectant is strongly required. In this study, we have developed an innovative sporicidal disinfection method that employs the combination of an aqueous ethanol solution, visible light irradiation, and a photocatalyst. We successfully produced a sporicidal disinfectant one hundred times as effective as commercially available PAA, while also resolving the hazards and odor problems associated with PAA. The method presented here can potentially be used as a replacement for the general disinfectants employed in the food and health industries.

No MeSH data available.


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Survival rate of B. subtilis spores for the indicated time under dark conditions after the treatment, either of commercially available peracetic acid (PAA) solution at various concentrations (15, 150, 500, 1000, or 1500 ppm) or of WO3 suspended in ethanol:water solution (8:2, v/v) after 12 h of visible light irradiation.Photocatalyst: 25 mg, light source: Xe lamp (vis) with L-42 filter (λ > 420 nm), liquid-phase volume: 50 mL, density of B. subtilis spores: 2.0 × 106 CFU/mL.
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f4: Survival rate of B. subtilis spores for the indicated time under dark conditions after the treatment, either of commercially available peracetic acid (PAA) solution at various concentrations (15, 150, 500, 1000, or 1500 ppm) or of WO3 suspended in ethanol:water solution (8:2, v/v) after 12 h of visible light irradiation.Photocatalyst: 25 mg, light source: Xe lamp (vis) with L-42 filter (λ > 420 nm), liquid-phase volume: 50 mL, density of B. subtilis spores: 2.0 × 106 CFU/mL.

Mentions: Next, the sporicidal performance of a suspension of WO3 in 8:2 (v/v) ethanol:water after 12 h of visible light irradiation was compared with that of the commonly used, commercially available PAA disinfectant. Because the amount of generated organic peroxide was estimated (see above) to be ca. 13.5 ppm, 15 ppm PAA was used in the comparison. Figure 4 shows that the bacterial spores were completely inactivated (~6-log decrease in survival) in the solution treated with WO3 after 4 h of illumination. In contrast, 15 ppm commercial PAA disinfectant solution did not provide appreciable killing (<0.5-log decrease) in the same interval. Testing at higher PAA concentrations revealed that the WO3 system exhibited a sporicidal performance equivalent to 1500 ppm PAA, indicating that our method has a sporicidal effect 100 times that of PAA. Additionally, we note that the suspension treated with WO3 contained not only acetic acid but also formic acid. We therefore presume that peroxyformic acid, which is a stronger oxidant than PAA, was produced in the presence of WO3. The generation of peroxyformic acid may account for the remarkable sporicidal performance of the suspension treated with WO3 compared to that observed in the suspension treated with the commercial PAA disinfectant.


Sporicidal performance induced by photocatalytic production of organic peroxide under visible light irradiation
Survival rate of B. subtilis spores for the indicated time under dark conditions after the treatment, either of commercially available peracetic acid (PAA) solution at various concentrations (15, 150, 500, 1000, or 1500 ppm) or of WO3 suspended in ethanol:water solution (8:2, v/v) after 12 h of visible light irradiation.Photocatalyst: 25 mg, light source: Xe lamp (vis) with L-42 filter (λ > 420 nm), liquid-phase volume: 50 mL, density of B. subtilis spores: 2.0 × 106 CFU/mL.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC5036025&req=5

f4: Survival rate of B. subtilis spores for the indicated time under dark conditions after the treatment, either of commercially available peracetic acid (PAA) solution at various concentrations (15, 150, 500, 1000, or 1500 ppm) or of WO3 suspended in ethanol:water solution (8:2, v/v) after 12 h of visible light irradiation.Photocatalyst: 25 mg, light source: Xe lamp (vis) with L-42 filter (λ > 420 nm), liquid-phase volume: 50 mL, density of B. subtilis spores: 2.0 × 106 CFU/mL.
Mentions: Next, the sporicidal performance of a suspension of WO3 in 8:2 (v/v) ethanol:water after 12 h of visible light irradiation was compared with that of the commonly used, commercially available PAA disinfectant. Because the amount of generated organic peroxide was estimated (see above) to be ca. 13.5 ppm, 15 ppm PAA was used in the comparison. Figure 4 shows that the bacterial spores were completely inactivated (~6-log decrease in survival) in the solution treated with WO3 after 4 h of illumination. In contrast, 15 ppm commercial PAA disinfectant solution did not provide appreciable killing (<0.5-log decrease) in the same interval. Testing at higher PAA concentrations revealed that the WO3 system exhibited a sporicidal performance equivalent to 1500 ppm PAA, indicating that our method has a sporicidal effect 100 times that of PAA. Additionally, we note that the suspension treated with WO3 contained not only acetic acid but also formic acid. We therefore presume that peroxyformic acid, which is a stronger oxidant than PAA, was produced in the presence of WO3. The generation of peroxyformic acid may account for the remarkable sporicidal performance of the suspension treated with WO3 compared to that observed in the suspension treated with the commercial PAA disinfectant.

View Article: PubMed Central - PubMed

ABSTRACT

Bacteria that cause serious food poisoning are known to sporulate under conditions of nutrient and water shortage. The resulting spores have much greater resistance to common sterilization methods, such as heating at 100&thinsp;&deg;C and exposure to various chemical agents. Because such bacteria cannot be inactivated with typical alcohol disinfectants, peroxyacetic acid (PAA) often is used, but PAA is a harmful agent that can seriously damage human health. Furthermore, concentrated hydrogen peroxide, which is also dangerous, must be used to prepare PAA. Thus, the development of a facile and safe sporicidal disinfectant is strongly required. In this study, we have developed an innovative sporicidal disinfection method that employs the combination of an aqueous ethanol solution, visible light irradiation, and a photocatalyst. We successfully produced a sporicidal disinfectant one hundred times as effective as commercially available PAA, while also resolving the hazards and odor problems associated with PAA. The method presented here can potentially be used as a replacement for the general disinfectants employed in the food and health industries.

No MeSH data available.


Related in: MedlinePlus