Does extra-cellular DNA play a role in biofilm formation of Listeria monocytogenes EGDe?
Special Symposium - Innovations in Food Technology (LMC Congress)
Innovations in Food Technology - Poster Session (Food - P2)
Keywords: biofilm, pathogens,
The foodborne pathogen, Listeria monocytogenes, is known to persist in food processing plants, and it has been reported that some strains are capable of forming biofilms. The mechanisms have not been elucidated but seem to depend on factors such as temperatures and inducing compounds [Gravesen, et al. (2005)]. The occurrence of extra-cellular DNA in the matrix of biofilms has been reported to influence the initial attachment and/or the biofilm structure of Pseudomonas and Streptococcus species. Using microtiter based biofilm assays with the DNA stain propidium iodide, we found that L. monocytogenes EGDe released extra-cellular DNA mainly during stationary growth. In order to test a possible role of this extra-cellular DNA we investigated the effect of DNaseI treatment on the attachment and stability of a L. monocytogenes biofilm. The DNaseI treatment was performed at different timepoints after inoculation (0, 2, 4, 6, 12 and 24h) of the microtiter based biofilm. The treatment reduced the biofilm formation to less than 40% of the untreated at all timepoints even when the DNaseI was employed at low amounts (10γ). Confocal laser microscopy images of attachment in static chambers, and flow-cell biofilms have further supported these data.
These results strongly indicate that extra-cellular DNA plays an essential role on the attachment and stability of a L. monocytogenes biofilm even at the later stages of biofilm formation (24h). This knowledge might show useful for the sanitation processes at food production plants.
Gravesen, A., Lekkas, C., and Knochel, S. (2005). Surface attachment of Listeria monocytogenes is induced by sublethal concentrations of alcohol at low temperatures. Appl.Environ.Microbiol. 71 (9): 5601 - 5603.
Presented Thursday 20, 13:30 to 14:40, in session Innovations in Food Technology - Poster Session (Food - P2).
