Submitted to: Meeting Abstract
Publication Type: Abstract only
Publication Acceptance Date: 2/9/2005
Publication Date: 8/14/2005
Citation: Solomon, E.B., Niemira, B.A., Sapers, G.M., Annous, B.A. 2005. Comparison of biofilm formation by salmonella spp. originating from produce, animal, and clinical sources (abstract). International Association for Food Protection. Pager No. P1-48. Interpretive Summary:
Technical Abstract: Cantaloupe melons have been implicated in six outbreaks of salmonellosis since 1990. Research in our laboratory has documented the formation of biofilms by Salmonella on cantaloupe surfaces. The entrapment of cells of Salmonella within a biofilm is likely responsible for enhanced sanitizer resistance. Two major components of Salmonella biofilms have recently been discovered: curli and cellulose. Our objective was to investigate whether Salmonella isolates from produce sources exhibited increased biofilm formation compared to those originating from animal and clinical sources, and to screen our collection for cellulose and curli production. Biofilm formation was determined using a crystal violet staining method. Curli and cellulose production were monitored by assessing morphotypes on LB agar without salt containing Congo Red and fluorescence on LB agar containing calcofluor, respectively. The crystal violet binding assay demonstrated no significant differences in biofilm formation by isolates from any source when tested in either LB broth supplemented with 2% glucose, tryptic soy broth, or 1/20th-strength tryptic soy broth. One hundred percent of clinical isolates exhibited curli biosynthesis and 73% demonstrated cellulose production. All meat-related isolates formed curli and 84% produced cellulose. Eighty percent of produce-related isolates produced curli but only 52% produced cellulose. Crystal violet binding was not statistically higher in isolates of any morphotype, but was related to the media in which the strains were tested. Results indicate that biofilm formation was not dependent on the source of the test isolate and suggest a correlation between curli and cellulose production and biofilm formation.