Exploiting Violet-Blue Light to Kill Campylobacter jejuni : Analysis of Global Responses, Modeling of Transcription Factor Activities, and Identification of Protein Targets

Abstract

Campylobacteriosis caused by C. jejuni is one of the most widespread zoonotic enteric diseases worldwide and represents an enormous human health and economic burden, compounded by the emergence of antibiotic-resistant strains. New interventions are urgently needed to reduce food-chain contamination.

New Insights into the Bacterial Targets of Antimicrobial Blue Light

“…Herein, we investigated the targets involved in the aBL-mediated killing of bacteria for three clinically important bacterial species: P. aeruginosa , S. aureus , and E. coli . Previous studies have suggested that ROS generation by aBL exposure could lead to the damage of multiple nonspecific targets, including DNA, proteins, lipids, and the cell wall/membrane ( 11 – 13 ).…”

“…Protein damage has also been suggested to occur as a result of aBL exposure ( 12 ). Therefore, we evaluated whether aBL could promote protein degradation.…”

“…To date, the most accepted hypothesis is that aBL elicits its antimicrobial effects as a result of photoexcitation of endogenous chromophores (e.g., porphyrins and/or flavins) to produce cytotoxic reactive oxygen species (ROS), which trigger cellular damage to lipids and proteins ( 11 – 13 ). It was also suggested that a flavin photoproduct, lumichrome, may play a role as an endogenous photosensitizer that is excitable by shorter aBL wavelength ( 14 ).…”

“…Indeed, although the bacterial targets of aBL have not been fully elucidated, studies have suggested an increase in membrane permeability due to lipid peroxidation with a consequent decrease in unsaturated fatty acids ( 11 – 13 ). More recently, Walker and collaborators reported a two-phase protein damage/oxidative stress response to aBL in Campylobacter jejuni , a foodborne zoonotic pathogen ( 12 ).…”

“…Indeed, although the bacterial targets of aBL have not been fully elucidated, studies have suggested an increase in membrane permeability due to lipid peroxidation with a consequent decrease in unsaturated fatty acids ( 11 – 13 ). More recently, Walker and collaborators reported a two-phase protein damage/oxidative stress response to aBL in Campylobacter jejuni , a foodborne zoonotic pathogen ( 12 ). The authors showed that there is a specific regulation of genes that encode proteins involved in the cellular response to global protein damage, which depends on the light dose, i.e., whether it is bacteriostatic or bactericidal.…”