title: Attachment and biofilm formation by Escherichia coli O157:H7 on stainless steel as influenced by exopolysaccharide production, nutrient availability, and temperature.
abstract: The influence of exopolysaccharide (EPS) production, nutrient availability, and temperature on attachment and biofilm formation by Escherichia coli O157:H7 strains ATCC 43895 (wild type) and 43895-EPS (extensive EPS-producing mutant) on stainless steel coupons (SSCs) was investigated. Cells grown on heated lettuce juice agar and modified tryptic soy agar were suspended in phosphate-buffered saline (PBS). SSCs were immersed in the cell suspension (10(9) CFU/ml) at 4 degrees C for 24 h. Biofilm formation by cells attached to SSCs as affected by immersing in 10% tryptic soy broth (TSB), lettuce juice broth (LJB), and minimal salts broth (MSB) at 12 and 22 degrees C was studied. A significantly lower number of strain 43895-EPS cells, compared to strain ATCC 43895 cells, attached to SSCs during a 24-h incubation (4 degrees C) period in PBS suspension. Neither strain formed a biofilm on SSCs subsequently immersed in 10% TSB or LJB, but both strains formed biofilms in MSB. Populations of attached cells and planktonic cells of strain ATCC 43895 gradually decreased during incubation for 6 days in LJB at 22 degrees C, but populations of strain 43895-EPS remained constant for 6 days at 22 degrees C, indicating that the EPS-producing mutant, compared to the wild-type strain, has a higher tolerance to the low-nutrient environment presented by LJB. It is concluded that EPS production by E. coli O157:H7 inhibits attachment to SSCs and that reduced nutrient availability enhances biofilm formation. Biofilms formed under conditions favorable for EPS production may protect E. coli O157:H7 against sanitizers used to decontaminate lettuce and produce processing environments. Studies are under way to test this hypothesis.
authors.affiliation: Center for Food Safety and Department of Food Science and Technology, University of Georgia, 1109 Experiment Street, Griffin, Georgia 30223-1797, USA.
authors.forename: Jee-Hoon
authors.initials: JH
authors.lastname: Ryu
authors.forename: Hoikyung
authors.initials: H
authors.lastname: Kim
authors.forename: Larry R
authors.initials: LR
authors.lastname: Beuchat
mesh_terms: D001422:Bacterial Adhesion; D018441:Biofilms / Q000254:growth & development*; D018533:Biomass; D015169:Colony Count, Microbial; D004866:Equipment Contamination; D019453:Escherichia coli O157 / Q000502:physiology*; D005506:Food Contamination / Q000032:analysis*; D005516:Food Microbiology; D005519:Food Preservation; D018545:Lactuca / Q000382:microbiology; D011135:Polysaccharides, Bacterial / Q000096:biosynthesis*; D013193:Stainless Steel; D013696:Temperature; D013997:Time Factors
chemical_list: D011135:Polysaccharides, Bacterial; D013193:Stainless Steel