title: Absence of association of autoinducer-2-based quorum sensing with heat and acid resistance of Salmonella.
abstract: This study used various approaches to investigate the potential association of autoinducer-2 (AI-2) presence with thermal and acid resistance of Salmonella cultures. Salmonella Thompson strains RM1987N (luxS-positive; AI-2 positive) and RM1987NLUX (luxS-negative; AI-2 negative) were exposed to 55 °C (6 h) in Luria-Bertani (LB) broth, while the luxS-negative S. Thompson strain and a Salmonella Typhimurium luxS-positive strain were exposed to 55 °C in AI-2-positive or -negative preconditioned (PC) media derived from S. Thompson and Escherichia coli O157:H7 luxS-positive and -negative strains. In addition, the luxS-negative S. Thompson strain was subjected to pH 3.5 PC media (35 °C, 6 h) with or without AI-2 activity, and acid-adapted or nonadapted S. Thompson strains were exposed to pH 3.0 LB broth (35 °C, 6 h). Surviving bacterial populations during exposure to 55 °C LB were not different between luxS-negative and -positive S. Thompson strains. In addition, heating at 55 °C of the luxS-negative S. Thompson strain in AI-2-positive and -negative PC media resulted in similar (P ≥ 0.05) survivor counts. Furthermore, surviving cell counts of S. Typhimurium (luxS-positive) in 55 °C AI-2-positive PC media were not different (P ≥ 0.05) than those in AI-2 negative PC media. No differences in surviving cell counts of the luxS-negative S. Thompson strain was found when exposed to pH 3.5 AI-2-positive and -negative PC media. Also, survivors of acid-adapted or nonadapted cells of luxS-negative and -positive S. Thompson strains were not different following exposure to pH 3.0 LB. The results indicated that, under the conditions of this study, AI-2-based quorum sensing did not appear to be associated with heat and acid resistance of Salmonella.
authors.affiliation: Center for Meat Safety & Quality, Food Safety Cluster, Dept. of Animal Sciences, 1171 Campus Delivery, Colorado State Univ., Fort Collins, CO 80523-1171, USA. john.sofos@colostate.edu
authors.forename: Yohan
authors.initials: Y
authors.lastname: Yoon
authors.forename: John N
authors.initials: JN
authors.lastname: Sofos
mesh_terms: D000222:Adaptation, Physiological; D001426:Bacterial Proteins / Q000378:metabolism*; D013437:Carbon-Sulfur Lyases / Q000378:metabolism*; D015169:Colony Count, Microbial; D017077:Culture Media, Conditioned / Q000378:metabolism; D019453:Escherichia coli O157 / Q000378:metabolism; D005516:Food Microbiology; D006714:Homoserine / Q000031:analogs & derivatives* / Q000378:metabolism; D006358:Hot Temperature; D006863:Hydrogen-Ion Concentration; D007783:Lactones / Q000378:metabolism*; D050296:Microbial Viability; D053038:Quorum Sensing; D012475:Salmonella / Q000254:growth & development / Q000502:physiology*; D012486:Salmonella typhimurium / Q000254:growth & development / Q000378:metabolism / Q000502:physiology; D013312:Stress, Physiological; D013997:Time Factors
chemical_list: D001426:Bacterial Proteins; D017077:Culture Media, Conditioned; D007783:Lactones; C091088:N-octanoylhomoserine lactone; D006714:Homoserine; D013437:Carbon-Sulfur Lyases; C117753:LuxS protein, Bacteria