title: Effects of a pulsed light-induced stress on Enterococcus faecalis.
abstract: OBJECTIVE
  Pulsed light (PL) technology is a surface decontamination process that can be used on food, packaging or water. PL efficiency may be limited by its low degree of penetration or because of a shadow effect. In these cases, surviving bacteria will be able to perceive PL as a stress. Such a stress was mimicked using low transmitted energy conditions, and its effects were investigated on the highly environmental adaptable bacterium Enterococcus faecalis V583.
  
  
  RESULTS
  In these laboratory conditions, a complete decontamination of the artificially inoculated medium was performed using energy doses as low as 1.8 J cm(-2) , while a treatment of 0.5, 1 and 1.2 J cm(-2) led to a 2.2, 6 and 7-log(10) CFU ml(-1) reduction in the initial bacterial population, respectively. Application of a 0.5 J cm(-2) pretreatment allowed the bacteria to resist more efficiently a 1.2 J cm(-2) subsequent PL dose. This 0.5 J cm(-2) treatment increased the bacterial mutation frequency and affected the abundance of 19 proteins as revealed by a global proteome analysis.
  
  
  CONCLUSIONS
  Enterococcus faecalis is able to adapt to a PL treatment, providing a molecular response to low-energy PL dose, leading to enhanced resistance to a subsequent treatment and increasing the mutation frequency.
  
  
  CONCLUSIONS
  This study gives further insights on Ent. faecalis capacities to adapt and to resist to stress.
authors.affiliation: LMSM, Laboratoire de Microbiologie-Signaux et Microenvironnement, EA 4312, Université de Rouen, Evreux, France.
authors.forename: S
authors.initials: S
authors.lastname: Massier
authors.forename: E
authors.initials: E
authors.lastname: Bouffartigues
authors.forename: A
authors.initials: A
authors.lastname: Rincé
authors.forename: O
authors.initials: O
authors.lastname: Maillot
authors.forename: M G J
authors.initials: MG
authors.lastname: Feuilloley
authors.forename: N
authors.initials: N
authors.lastname: Orange
authors.forename: S
authors.initials: S
authors.lastname: Chevalier
mesh_terms: D000222:Adaptation, Physiological; D001426:Bacterial Proteins / Q000235:genetics; D003666:Decontamination / Q000379:methods*; D013293:Enterococcus faecalis / Q000235:genetics / Q000528:radiation effects*; D008027:Light; D050296:Microbial Viability; D059645:Mutation Rate; D020543:Proteome / Q000032:analysis; D013312:Stress, Physiological
chemical_list: D001426:Bacterial Proteins; D020543:Proteome