Mutagenesis in
            <i>Escherichia coli</i>
            by Visible Light

Webb, Robert B.; Malina, Mylan M.

doi:10.1126/science.156.3778.1104

Cited by 90 publications

(21 citation statements)

References 10 publications

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“…Visible light (408-750 nm) has been found to be mutagenic and to cause metabolic and membrane damage to bacteria such as Escherichia coli [29,30]. Feuerstein et al [24] suggested that increases in temperature could damage bacteria after exposure to blue light.…”

Section: Discussionmentioning

confidence: 99%

Phototoxic effect of blue light on the planktonic and biofilm state of anaerobic periodontal pathogens

Song

Lee

et al. 2013

J Periodontal Implant Sci

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PurposeThe purpose of this study was to compare the phototoxic effects of blue light exposure on periodontal pathogens in both planktonic and biofilm cultures.MethodsStrains of Aggregatibacter actinomycetemcomitans, Fusobacterium nucleatum, and Porphyromonas gingivalis, in planktonic or biofilm states, were exposed to visible light at wavelengths of 400.520 nm. A quartz-tungsten-halogen lamp at a power density of 500 mW/cm2 was used for the light source. Each sample was exposed to 15, 30, 60, 90, or 120 seconds of each bacterial strain in the planktonic or biofilm state. Confocal scanning laser microscopy (CSLM) was used to observe the distribution of live/dead bacterial cells in biofilms. After light exposure, the bacterial killing rates were calculated from colony forming unit (CFU) counts.ResultsCLSM images that were obtained from biofilms showed a mixture of dead and live bacterial cells extending to a depth of 30-45 µm. Obvious differences in the live-to-dead bacterial cell ratio were found in P. gingivalis biofilm according to light exposure time. In the planktonic state, almost all bacteria were killed with 60 seconds of light exposure to F. nucleatum (99.1%) and with 15 seconds to P. gingivalis (100%). In the biofilm state, however, only the CFU of P. gingivalis demonstrated a decreasing tendency with increasing light exposure time, and there was a lower efficacy of phototoxicity to P. gingivalis as biofilm than in the planktonic state.ConclusionsBlue light exposure using a dental halogen curing unit is effective in reducing periodontal pathogens in the planktonic state. It is recommended that an adjunctive exogenous photosensitizer be used and that pathogens be exposed to visible light for clinical antimicrobial periodontal therapy.

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Section: Discussionmentioning

confidence: 99%

Phototoxic effect of blue light on the planktonic and biofilm state of anaerobic periodontal pathogens

Song

Lee

et al. 2013

J Periodontal Implant Sci

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“…The near-UV region utilized in this experiment has been shown to be responsible for many unique effects. In bacteria, near-UV has been found to be mutagenic (26)(27)(28)(29). The ability of DNA to transform bacterial cells was decreased by near-UV (30,31).…”

Section: Discussionmentioning

confidence: 99%

Effect of Near-Ultraviolet and Visible Light on Mammalian Cells in Culture II. Formation of Toxic Photoproducts in Tissue Culture Medium by Blacklight

Stoien

Wang

1974

Proc. Natl. Acad. Sci. U.S.A.

133

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Near-ultraviolet radiation was found to be lethal for mammalian cells in Dulbecco's modified Eagle's medium without serum or phenol red. Irradiation of the cells with near-ultraviolet light while the cells were in phosphate-buffered-saline abolished the lethal effect. When only the medium was irradiated followed by the addition of unirradiated cells and serum, the cells were still killed. The photoactive components of the medium for this effect were riboflavin, tryptophan, and tyrosine. When riboflavin was deleted from the medium being irradiated and added later, almost no killing was detected. Irradiation of salt solution of riboflavin and tryptophan or riboflavin and tyrosine, resulted in cell killing. Little Irradiation of Cells. The light sources used in this study were two General Electric F15T8 BLB integral filter blacklight tubes with emission in the 300-to 420-nm range peaking at 365 nm (12). Light exposure was carried out in covered Falcon 3002 60-mm dishes placed approximately 20 cm below the light source. The lids of these dishes exclude light below 300 nm (6). Exposure intensity was 4 sW/mm2 at the cell surface, as measured by a Blak-ray meter J-221 (Ultraviolet Products, Inc.). Temperature was monitored and regulated to avoid any effect due to heating by the light source. The cells were trypsinized and plated in medium containing serum but no phenol red, 18 hr before exposure to blacklight. Twenty minutes before irradiation, the medium was removed and replaced with either 3.5 ml of phosphate-buffered saline containing NaCl, KC1, Na2HPO4, and KH2PO4; or MEM free of both phenol red and serum. The dishes were placed in the exposure chamber under 10% CO2 for 20 min before the light was turned on. At various intervals, dishes were removed from the light and kept in the dark in the same chamber. After the last dishes were removed from the light, serum was added to all dishes.Irradiation of Medium or Medium Components. Exposure conditions were similar to those of the last section except that no cells were present and only the aqueous solutions of medium components were exposed. The basic mixture (BaM) employed, to which other components were selectively added, contained NaCl, KC1, CaC12, MgSO4, NaH2PO4, Fe(NO3)3, glucose, inositol, cysteine, and glutamine. For the determination of the medium components responsible for photoproduct formation, other ingredients were added to BaM: (1) aminoacid solution (AA) containing arginine, isoleucine, leucine, lysine, methionine, threonine, valine, glycine, and serine; (2) vitamin solution (Vit) containing nicotinamide, thiamine, choline, D-pantothenic acid and pyridoxine; (3) one or more of the following compounds: histidine, phenylalanine, tryptophan, tyrosine, and riboflavin. After irradiation, the missing MEM ingredients and serum were added to the dishes fol-

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“…Bacterial mutagenesis caused by visible light was first reported almost 40 years ago (Webb & Malina, 1967). Later studies suggested an antibacterial effect of visible light in the presence of exogenous photosensitizers or when applied to porphyrin-producing bacteria, such as Porphyromonas and Prevotella species (Wilson, 1994;Henry et al, 1995Henry et al, , 1996Konig et al, 2000;Soukos et al, 2005).…”

Section: Introductionmentioning

confidence: 99%

Effect of visible light on malodour production by mixed oral microflora

Sterer

Feuerstein

2005

Journal of Medical Microbiology

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Oral malodour is considered to be caused by the proteolytic activity of anaerobic Gram-negative oral bacteria. In a previous study, it was shown that these bacteria were susceptible to blue light (wavelengths of 400-500 nm). In this study, the effect of blue light on malodour production by mixed oral microflora was tested in a salivary incubation assay. Whole saliva samples were exposed to a xenon light source for 30, 60, 120 and 240 s, equivalent to fluences of 34, 68, 137 and 274 J cm À2 , respectively. Malodour was scored by two judges. The levels of volatile sulfide compounds (VSC) were measured using a sulfide monitor (Halimeter), the microbial population was assessed using viable counts and microscopy, salivary protein degradation was followed by SDS-PAGE densitometry and VSC-producing bacteria were demonstrated using a differential agar. The results showed that the exposure of mixed salivary microflora to blue light caused a reduction in malodour production concomitant with a selective inhibitory effect on the population of Gram-negative oral bacteria. These results suggest that light exposure might have clinical applications for the treatment of oral malodour.

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Mutagenesis in Escherichia coli by Visible Light

Cited by 90 publications

References 10 publications

Phototoxic effect of blue light on the planktonic and biofilm state of anaerobic periodontal pathogens

Phototoxic effect of blue light on the planktonic and biofilm state of anaerobic periodontal pathogens

Effect of Near-Ultraviolet and Visible Light on Mammalian Cells in Culture II. Formation of Toxic Photoproducts in Tissue Culture Medium by Blacklight

Effect of visible light on malodour production by mixed oral microflora

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