Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
8844265 | International Journal of Food Microbiology | 2018 | 8 Pages |
Abstract
Biofilms are known to play important roles in bacterial survival and persistence in food-processing environments. This study aimed to determine the ability of the top 7 STEC serotypes to form biofilms on polystyrene (POL) and stainless steel (SS) plates and to quantify their survival and transfer from dry-surface biofilms to lettuce pieces. The ability of 14 STEC strains to form biofilms on these two materials at different exposure times and temperatures was assessed using crystal violet, Congo red and SEM. At 10â¯Â°C all serotypes were weak biofilm producers on both surfaces. In contrast, serotypes O45-040, O45-445, O103-102, O103-670 and O157-R508 were strong biofilm producers at 25â¯Â°C. Strains O103-102, O103-670, O111-CFS, O111-053 and O157:H7-R508 were expressers of curli. Under scanning electron microscopy, strains O103-670, O111-CFS, O157-R508, and O121-083 formed more discernible multilayer, mature biofilms on SS coupons. Regardless of the surface (POL/SS), all STEC strains were able to transfer viable cells onto fresh lettuce within a short contact time (2â¯min) to varying degrees (up to 6.35â¯logâ¯cfu/g). On POL, viable cell of almost all serotypes exhibited decreased detachment (pâ¯=â¯0.001) over 6â¯days; while after 30â¯days on SS, serotypes O45-040, O103-102, O103-670, O111-053, O111-CFS, O121-083, O145-231 O157:H7-R508 and O157:H7-122 were transferred to lettuce. After enrichment, all 14 STEC strains were recovered from dry-surface biofilms on POL and SS plates after 30â¯days. Results demonstrated that the top 7 STEC remained viable within dry-surface biofilms for at least 30â¯days, transferring to lettuce within 2â¯min of exposure and acting as a source of adulteration.
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Authors
Emelia Hornam Adator, Meining Cheng, Rick Holley, Tim McAllister, Claudia Narvaez-Bravo,