Effect of High Intensity Blue Light on Fusobacterium nucleatum Membrane Integrity

Abstract

Oral malodour is considered to be caused mainly by the production of volatile sulfide compounds (VSC) by anaerobic gram‐negative oral bacteria. Previous studies showed that these bacteria were susceptible to blue light phototoxicity mediated by the production of reactive oxygen species (ROS). In the present study, we tested the effect of blue light on the integrity Fusobacterium nucleatum's membrane, cellular proteins and DNA. Bacterial samples were exposed to high intensity blue light for 0, 70, 140 and 280 s (i.e. fluences of 0, 96, 192 and 384 J cm−2, respectively). Following light exposure, bacterial samples were examined for membrane damage using fluorescence microscopy, intra‐cellular protein analysis using electrophoresis (SDS‐PAGE) and DNA fragmentation using ultra–filtration. Results showed that the increasing exposure of bacterial samples to blue light caused increased membrane permeability concomitant with a reduction in intra‐cellular proteins and DNA fragments content. These results suggest that membrane damage is the main effect of high intensity blue light exposure on malodour producing bacteria.

Blue Light Enhances Fluoride Anticariogenic Activity against Streptococcus mutans

“…Previously, we have shown that exposing bacterial cells to a sub-lethal dosage of blue light increases their cell membrane permeability [9,11], and this suggested that this effect may increase the efficacy of antibacterial agents. In this study, we examined the combined effect of sub-lethal blue light and sodium fluoride on the cariogenicity of Streptococcus mutans in a biofilm configuration.…”

Effect of Silver Nanoparticles on Blue Light Phototoxicity against Fusobacterium nucleatum

“…Previous studies showed that sub-lethal dosage of blue light can increase cell membrane permeability in Fusobacterium nucleatum [13,14] and suggested that this effect was mediated through the production of reactive oxygen species [11]. In the present study, we tested the combined effect of sub-lethal blue light and silver nanoparticles on the ability of Fusobacterium nucleatum to produce malodor, its cell membrane integrity, and measured the levels of ROS produced following this treatment in order to understand the mechanism for the combined phototoxic effect.…”

“…Previous studies have demonstrated the phototoxic effect of blue light against malodor producing bacteria [10] with or without the added effect of photosensitizers [11] or photoactivators [12]. Furthermore, the main antibacterial mechanism of blue light against Fusobacterium nucleatum was shown to be membrane damage [13] that could be leveraged to increase the efficacy of other antibacterial agents [14]. The aim of the present study was to test the added effect of silver nanoparticles on blue light phototoxicity against Fusobacterium nucleatum.…”

Effect of Sublethal Blue Light on Herbal Extract Activity Against Volatile Sulfide Compound Production by Fusobacterium nucleatum

“…Previously, we showed that sublethal dosage of blue light can increase cell membrane permeability in Fusobacterium nucleatum (10). We postulated that this effect may increase the efficacy of other antibacterial agents.…”