期刊
JOURNAL OF FOOD PROTECTION
卷 67, 期 10, 页码 2123-2131出版社
INT ASSOC FOOD PROTECTION
DOI: 10.4315/0362-028X-67.10.2123
关键词
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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 4degreesC for 24 It. 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 22degreesC 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 (4degreesC) 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 22degreesC, but populations of strain 43895-EPS remained constant for 6 days at 22degreesC, 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.
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