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Inactivation of Streptomyces phage ɸC31 by 405 nm light: Requirement for exogenous photosensitizers?

Tomb RM, Maclean M, Herron PR, Hoskisson PA, MacGregor SJ, Anderson JG - Bacteriophage (2014)

Bottom Line: Significant reductions in phage titer occurred when exposed in nutrient-rich media, with ~3-, 5- and 7-log10 reductions achieved after exposure to doses of 0.3, 0.5 and 1.4 kJ/cm(2), respectively.When suspended in minimal media a 0.3-log10 reduction (P = 0.012) occurred after exposure to 306 J/cm(2): much lower than the 2.7- and > 2.5-log10 reductions achieved with the same dose in nutrient-rich, and porphyrin-supplemented media, suggesting inactivation is accelerated by the photo-activation of light-sensitive components in the media.The reduced susceptibility of viruses in minimal media, compared with that of other microorganisms, provides further evidence that the antimicrobial action of 405 nm light is predominantly due to the photo-excitation of endogenous photosensitive molecules such as porphyrins within susceptible microorganisms.

View Article: PubMed Central - PubMed

Affiliation: The Robertson Trust Laboratory for Electronic Sterilisation Technologies; University of Strathclyde; Glasgow, Scotland UK ; Strathclyde Institute of Pharmacy and Biomedical Sciences; University of Strathclyde; Glasgow, Scotland UK.

ABSTRACT
Exposure to narrowband violet-blue light around 405 nm wavelength can induce lethal oxidative damage to bacteria and fungi, however effects on viruses are unknown. As photosensitive porphyrin molecules are involved in the microbicidal inactivation mechanism, and since porphyrins are absent in viruses, then any damaging effects of 405 nm light on viruses might appear unlikely. This study used the bacteriophage ɸC31, as a surrogate for non-enveloped double-stranded DNA viruses, to establish whether 405 nm light can induce virucidal effects. Exposure of ɸC31 suspended in minimal media, nutrient-rich media, and porphyrin solution, demonstrated differing sensitivity of the phage. Significant reductions in phage titer occurred when exposed in nutrient-rich media, with ~3-, 5- and 7-log10 reductions achieved after exposure to doses of 0.3, 0.5 and 1.4 kJ/cm(2), respectively. When suspended in minimal media a 0.3-log10 reduction (P = 0.012) occurred after exposure to 306 J/cm(2): much lower than the 2.7- and > 2.5-log10 reductions achieved with the same dose in nutrient-rich, and porphyrin-supplemented media, suggesting inactivation is accelerated by the photo-activation of light-sensitive components in the media. This study provides the first evidence of the interaction of narrowband 405 nm light with viruses, and demonstrates that viral susceptibility to 405 nm light can be significantly enhanced by involvement of exogenous photosensitive components. The reduced susceptibility of viruses in minimal media, compared with that of other microorganisms, provides further evidence that the antimicrobial action of 405 nm light is predominantly due to the photo-excitation of endogenous photosensitive molecules such as porphyrins within susceptible microorganisms.

No MeSH data available.


Related in: MedlinePlus

Figure 2. 405 nm light inactivation of bacteriophage ɸC31 suspended in nutrient broth at a range of population densities. The light irradiance used was 56.7 mW/cm2. “*” indicates light-exposed samples that were significantly different to the equivalent non-exposed control samples (P ≤ 0.05). No significant decrease was observed in the final control populations (P ≥ 0.05).
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Figure 2: Figure 2. 405 nm light inactivation of bacteriophage ɸC31 suspended in nutrient broth at a range of population densities. The light irradiance used was 56.7 mW/cm2. “*” indicates light-exposed samples that were significantly different to the equivalent non-exposed control samples (P ≤ 0.05). No significant decrease was observed in the final control populations (P ≥ 0.05).

Mentions: In order to determine the effect of 405 nm light (Fig. 1) on ɸC31, bacteriophages were suspended in NB and exposed to 405 nm light at an irradiance of 56.7 mW/cm2 (Fig. 2). Successful inactivation was achieved, with the general trend showing relatively linear kinetics, with an increasing dose resulting in decreasing bacteriophage population. In the case of the 103 PFU/ml population, significant inactivation was achieved after a dose of 153.1 J/cm2 (P = 0.016) and 2.7-log10 reduction achieved after exposure to 306.2 J/cm2 compared with the equivalent controls.


Inactivation of Streptomyces phage ɸC31 by 405 nm light: Requirement for exogenous photosensitizers?

Tomb RM, Maclean M, Herron PR, Hoskisson PA, MacGregor SJ, Anderson JG - Bacteriophage (2014)

Figure 2. 405 nm light inactivation of bacteriophage ɸC31 suspended in nutrient broth at a range of population densities. The light irradiance used was 56.7 mW/cm2. “*” indicates light-exposed samples that were significantly different to the equivalent non-exposed control samples (P ≤ 0.05). No significant decrease was observed in the final control populations (P ≥ 0.05).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4116386&req=5

Figure 2: Figure 2. 405 nm light inactivation of bacteriophage ɸC31 suspended in nutrient broth at a range of population densities. The light irradiance used was 56.7 mW/cm2. “*” indicates light-exposed samples that were significantly different to the equivalent non-exposed control samples (P ≤ 0.05). No significant decrease was observed in the final control populations (P ≥ 0.05).
Mentions: In order to determine the effect of 405 nm light (Fig. 1) on ɸC31, bacteriophages were suspended in NB and exposed to 405 nm light at an irradiance of 56.7 mW/cm2 (Fig. 2). Successful inactivation was achieved, with the general trend showing relatively linear kinetics, with an increasing dose resulting in decreasing bacteriophage population. In the case of the 103 PFU/ml population, significant inactivation was achieved after a dose of 153.1 J/cm2 (P = 0.016) and 2.7-log10 reduction achieved after exposure to 306.2 J/cm2 compared with the equivalent controls.

Bottom Line: Significant reductions in phage titer occurred when exposed in nutrient-rich media, with ~3-, 5- and 7-log10 reductions achieved after exposure to doses of 0.3, 0.5 and 1.4 kJ/cm(2), respectively.When suspended in minimal media a 0.3-log10 reduction (P = 0.012) occurred after exposure to 306 J/cm(2): much lower than the 2.7- and > 2.5-log10 reductions achieved with the same dose in nutrient-rich, and porphyrin-supplemented media, suggesting inactivation is accelerated by the photo-activation of light-sensitive components in the media.The reduced susceptibility of viruses in minimal media, compared with that of other microorganisms, provides further evidence that the antimicrobial action of 405 nm light is predominantly due to the photo-excitation of endogenous photosensitive molecules such as porphyrins within susceptible microorganisms.

View Article: PubMed Central - PubMed

Affiliation: The Robertson Trust Laboratory for Electronic Sterilisation Technologies; University of Strathclyde; Glasgow, Scotland UK ; Strathclyde Institute of Pharmacy and Biomedical Sciences; University of Strathclyde; Glasgow, Scotland UK.

ABSTRACT
Exposure to narrowband violet-blue light around 405 nm wavelength can induce lethal oxidative damage to bacteria and fungi, however effects on viruses are unknown. As photosensitive porphyrin molecules are involved in the microbicidal inactivation mechanism, and since porphyrins are absent in viruses, then any damaging effects of 405 nm light on viruses might appear unlikely. This study used the bacteriophage ɸC31, as a surrogate for non-enveloped double-stranded DNA viruses, to establish whether 405 nm light can induce virucidal effects. Exposure of ɸC31 suspended in minimal media, nutrient-rich media, and porphyrin solution, demonstrated differing sensitivity of the phage. Significant reductions in phage titer occurred when exposed in nutrient-rich media, with ~3-, 5- and 7-log10 reductions achieved after exposure to doses of 0.3, 0.5 and 1.4 kJ/cm(2), respectively. When suspended in minimal media a 0.3-log10 reduction (P = 0.012) occurred after exposure to 306 J/cm(2): much lower than the 2.7- and > 2.5-log10 reductions achieved with the same dose in nutrient-rich, and porphyrin-supplemented media, suggesting inactivation is accelerated by the photo-activation of light-sensitive components in the media. This study provides the first evidence of the interaction of narrowband 405 nm light with viruses, and demonstrates that viral susceptibility to 405 nm light can be significantly enhanced by involvement of exogenous photosensitive components. The reduced susceptibility of viruses in minimal media, compared with that of other microorganisms, provides further evidence that the antimicrobial action of 405 nm light is predominantly due to the photo-excitation of endogenous photosensitive molecules such as porphyrins within susceptible microorganisms.

No MeSH data available.


Related in: MedlinePlus