Lethal effects of high intensity violet 405-nm light on saccharomyces cerevisiae, candida albicans and on dormant and germinating spores of aspergillus niger

L.E. Murdoch, K. McKenzie, M. MacLean, S.J. MacGregor, J.G. Anderson

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Abstract

This study assessed the effects of high-intensity violet light on selected yeast and mould fungi. Cell suspensions of Saccharomyces cerevisiae, Candida albicans, and dormant and germinating spores (conidia) of the mould Aspergillus niger were exposed to high-intensity narrow band violet light with peak output at 405 nm generated from a light-emitting diode (LED) array. All three fungal species were inactivated by the 405-nm light without a requirement for addition of exogenous photosensitiser chemicals. Of the fungal species tested, S. cerevisiae was most sensitive and dormant conidia of A. niger were most resistant to 405-nm light exposure. Five-log10 colony forming units per millilitre (CFU ml1) reductions of the tested species required exposure doses of 288 J cm2 for S. cerevisiae, 576 J cm2 for C. albicans, and a much higher value of 2.3 kJ cm2 for dormant conidia of A. niger. During germination, A. niger conidia became more sensitive to 405-nm light exposure and sensitivity increased as germination progressed over an 8 h test period. Light exposure under aerobic
and anaerobic conditions, together with results obtained using ascorbic acid as a scavenger of reactive oxygen species, revealed that 405-nm light inactivation in fungi involved an oxygen-dependent mechanism, as previously described in bacteria. The inactivation results achieved with yeast cells and fungal spores together with operational advantages associated with the use of a visible (nonultraviolet (UV)) light source highlight the potential of 405-nm light for fungal decontamination applications.
LanguageEnglish
Pages519-527
Number of pages9
JournalFungal biology
Volume117
Issue number7-8
Early online date30 May 2013
DOIs
Publication statusPublished - Jul 2013

Fingerprint

Aspergillus niger
Candida
Aspergillus
Spores
Candida albicans
Yeast
Saccharomyces cerevisiae
spore
spores
Fungal Spores
Light
conidia
Fungi
Germination
molds (fungi)
inactivation
Yeasts
yeast
germination
yeasts

Keywords

  • lethal effects
  • high intensity
  • violet 405-nm light
  • saccharomyces cerevisiae
  • dormant and germinating spores
  • Aspergillus niger
  • candida albicans

Cite this

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title = "Lethal effects of high intensity violet 405-nm light on saccharomyces cerevisiae, candida albicans and on dormant and germinating spores of aspergillus niger",
abstract = "This study assessed the effects of high-intensity violet light on selected yeast and mould fungi. Cell suspensions of Saccharomyces cerevisiae, Candida albicans, and dormant and germinating spores (conidia) of the mould Aspergillus niger were exposed to high-intensity narrow band violet light with peak output at 405 nm generated from a light-emitting diode (LED) array. All three fungal species were inactivated by the 405-nm light without a requirement for addition of exogenous photosensitiser chemicals. Of the fungal species tested, S. cerevisiae was most sensitive and dormant conidia of A. niger were most resistant to 405-nm light exposure. Five-log10 colony forming units per millilitre (CFU ml1) reductions of the tested species required exposure doses of 288 J cm2 for S. cerevisiae, 576 J cm2 for C. albicans, and a much higher value of 2.3 kJ cm2 for dormant conidia of A. niger. During germination, A. niger conidia became more sensitive to 405-nm light exposure and sensitivity increased as germination progressed over an 8 h test period. Light exposure under aerobicand anaerobic conditions, together with results obtained using ascorbic acid as a scavenger of reactive oxygen species, revealed that 405-nm light inactivation in fungi involved an oxygen-dependent mechanism, as previously described in bacteria. The inactivation results achieved with yeast cells and fungal spores together with operational advantages associated with the use of a visible (nonultraviolet (UV)) light source highlight the potential of 405-nm light for fungal decontamination applications.",
keywords = "lethal effects, high intensity, violet 405-nm light, saccharomyces cerevisiae, dormant and germinating spores, Aspergillus niger, candida albicans",
author = "L.E. Murdoch and K. McKenzie and M. MacLean and S.J. MacGregor and J.G. Anderson",
note = "NOTICE: this is the author’s version of a work that was accepted for publication in Fungal Biology. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was subsequently published in Fungal Biology, VOL 117, ISSUE 7-8, (July–August 2013) DOI 10.1016/j.funbio.2013.05.004",
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AU - Murdoch, L.E.

AU - McKenzie, K.

AU - MacLean, M.

AU - MacGregor, S.J.

AU - Anderson, J.G.

N1 - NOTICE: this is the author’s version of a work that was accepted for publication in Fungal Biology. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was subsequently published in Fungal Biology, VOL 117, ISSUE 7-8, (July–August 2013) DOI 10.1016/j.funbio.2013.05.004

PY - 2013/7

Y1 - 2013/7

N2 - This study assessed the effects of high-intensity violet light on selected yeast and mould fungi. Cell suspensions of Saccharomyces cerevisiae, Candida albicans, and dormant and germinating spores (conidia) of the mould Aspergillus niger were exposed to high-intensity narrow band violet light with peak output at 405 nm generated from a light-emitting diode (LED) array. All three fungal species were inactivated by the 405-nm light without a requirement for addition of exogenous photosensitiser chemicals. Of the fungal species tested, S. cerevisiae was most sensitive and dormant conidia of A. niger were most resistant to 405-nm light exposure. Five-log10 colony forming units per millilitre (CFU ml1) reductions of the tested species required exposure doses of 288 J cm2 for S. cerevisiae, 576 J cm2 for C. albicans, and a much higher value of 2.3 kJ cm2 for dormant conidia of A. niger. During germination, A. niger conidia became more sensitive to 405-nm light exposure and sensitivity increased as germination progressed over an 8 h test period. Light exposure under aerobicand anaerobic conditions, together with results obtained using ascorbic acid as a scavenger of reactive oxygen species, revealed that 405-nm light inactivation in fungi involved an oxygen-dependent mechanism, as previously described in bacteria. The inactivation results achieved with yeast cells and fungal spores together with operational advantages associated with the use of a visible (nonultraviolet (UV)) light source highlight the potential of 405-nm light for fungal decontamination applications.

AB - This study assessed the effects of high-intensity violet light on selected yeast and mould fungi. Cell suspensions of Saccharomyces cerevisiae, Candida albicans, and dormant and germinating spores (conidia) of the mould Aspergillus niger were exposed to high-intensity narrow band violet light with peak output at 405 nm generated from a light-emitting diode (LED) array. All three fungal species were inactivated by the 405-nm light without a requirement for addition of exogenous photosensitiser chemicals. Of the fungal species tested, S. cerevisiae was most sensitive and dormant conidia of A. niger were most resistant to 405-nm light exposure. Five-log10 colony forming units per millilitre (CFU ml1) reductions of the tested species required exposure doses of 288 J cm2 for S. cerevisiae, 576 J cm2 for C. albicans, and a much higher value of 2.3 kJ cm2 for dormant conidia of A. niger. During germination, A. niger conidia became more sensitive to 405-nm light exposure and sensitivity increased as germination progressed over an 8 h test period. Light exposure under aerobicand anaerobic conditions, together with results obtained using ascorbic acid as a scavenger of reactive oxygen species, revealed that 405-nm light inactivation in fungi involved an oxygen-dependent mechanism, as previously described in bacteria. The inactivation results achieved with yeast cells and fungal spores together with operational advantages associated with the use of a visible (nonultraviolet (UV)) light source highlight the potential of 405-nm light for fungal decontamination applications.

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