title: Autoinducer-2-like activity on vegetable produce and its potential involvement in bacterial biofilm formation on tomatoes.
abstract: Quorum sensing employing autoinducer molecules is a strategy used by bacterial populations to coordinately modulate their response to environmental stresses and host defense mechanisms. The objectives of this study were to determine the levels of autoinducer-2 (AI-2)-like activity on selected vegetable produce and determine whether AI-2-like molecules can promote E. coli O157:H7 biofilm formation on tomatoes. Twelve different fruit and vegetable produce samples were screened for AI-2-like activity using autoinducer sensing V. harveyi biosensor strains. All samples except strawberries showed AI-2 activity albeit at varying levels, with eggplant having the highest levels. Tomatoes, when stored at 4 degrees C for 9 days, showed increasing levels of heterotrophic bacterial populations as compared to AI-2-like activity levels, which fluctuated. Rinses from Roma tomato surfaces that were stored at refrigeration temperature for up to 9 days caused a significant increase (1.8-3.6-fold as compared to the negative controls) in biofilm formation by luxS mutant (non AI-2 producing) generic E. coli and E. coli O157:H7 strains using a micro-titer plate-based biofilm assay. These results suggest that AI-2-like activity, which is present on the surfaces of tomatoes, has the potential to enhance the production of bacterial biofilms.
authors.affiliation: Poultry Science Department, Food Safety & Environmental Microbiology, Texas A&M University, College Station, TX 77843, USA.
authors.forename: Lingeng
authors.initials: L
authors.lastname: Lu
authors.forename: Michael E
authors.initials: ME
authors.lastname: Hume
authors.forename: Suresh D
authors.initials: SD
authors.lastname: Pillai
mesh_terms: D018441:Biofilms / Q000254:growth & development*; D019453:Escherichia coli O157 / Q000235:genetics / Q000502:physiology*; D029968:Escherichia coli Proteins / Q000096:biosynthesis / Q000737:chemistry / Q000235:genetics; D005511:Food Handling / Q000379:methods*; D005516:Food Microbiology; D005638:Fruit / Q000382:microbiology; D006714:Homoserine / Q000031:analogs & derivatives* / Q000032:analysis / Q000502:physiology; D007783:Lactones / Q000032:analysis; D018551:Solanum lycopersicum / Q000382:microbiology*; D013696:Temperature; D013997:Time Factors; D014675:Vegetables / Q000382:microbiology; D014733:Vibrio / Q000235:genetics / Q000502:physiology
chemical_list: D029968:Escherichia coli Proteins; D007783:Lactones; C091088:N-octanoylhomoserine lactone; D006714:Homoserine