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Keywords:

  • biofilm;
  • food-contact surfaces;
  • hydrophobicity;
  • Listeria monocytogenes;
  • motility;
  • temperature

Abstract

Aims:  To assess the ability of Listeria monocytogenes to form biofilm on different food-contact surfaces with regard to different temperatures, cellular hydrophobicity and motility.

Methods and Results:  Forty-four L. monocytogenes strains from food and food environment were tested for biofilm formation by crystal violet staining. Biofilm levels were significantly higher on glass at 4, 12 and 22°C, as compared with polystyrene and stainless steel. At 37°C, L. monocytogenes produced biofilm at significantly higher levels on glass and stainless steel, as compared with polystyrene. Hydrophobicity was significantly (P < 0·05) higher at 37°C than at 4, 12 and 22°C. Thirty (68·2%) of 44 strains tested showed swimming at 22°C and 4 (9·1%) of those were also motile at 12°C. No correlation was observed between swimming and biofilm production.

Conclusions: L. monocytogenes can adhere to and form biofilms on food-processing surfaces. Biofilm formation is significantly influenced by temperature, probably modifying cell surface hydrophobicity.

Significance and Impacts of the Study:  Biofilm formation creates major problems in the food industry because it may represent an important source of food contamination. Our results are therefore important in finding ways to prevent contamination because they contribute to a better understanding on how L. monocytogenes can establish biofilms in food industry and therefore survive in the processing environment.