@article{
author = "Milanov, Dubravka and Ašanin, Ružica and Vidić, Branka and Krnjaić, Dejan and Petrović, Jelena and Savić, Sara",
year = "2009",
abstract = "Listeria monocytogenes is the causative agent of numerous epidemics and sporadic cases of illness in humans. Food is the principal route of infection. Raw materials of animal and vegetable origin are the potential sources of contamination with this bacterium, particularly the foodstuff undergoing minimal processing procedures. However, in the recent years, emphasis has been increasingly laid on the importance of post-processing contamination occurring through the contact of products with contaminated surfaces in food-processing plants, where this bacterium can persist for months, even for years, as a biofilm. Although it appears to be widely accepted that L. monocytogenes forms biofilms on food-processing surfaces, there has been very little direct microscopical evidence to support this. In this study we investigated the ability of biofilm formation in 14 strains of Listeria monocytogenes of different origin. The biofilms were formed on stainless steel surfaces during 7 days of incubation in a tryptone soy broth supplemented with 0.6% yeast extract (TSB-YE) at a temperature of 25ºC. The developed structures were examined using scanning electron microscopy. Our results revealed significant differences among tested Listeria monocytogenes strains in terms of their ability to form a biofilm in given experimental conditions. Seven of 14 investigated strains of Listeria monocytogenes did not form a biofilm, and only individual bacterial cells were distributed over the stainless steel surface. The strains classified as biofilm producers formed structures of different appearances, from a uniform, confluent monolayer of bacterial cells to individual large, three-dimensional cell aggregates. All strains proved weak producers of extracellular polymeric substance., Listeria monocytogenes je uzročnik brojnih epidemija i sporadičnih slučajeva oboljenja ljudi, a hrana predstavlja glavni put prenošenja infekcije. Sirovine biljnog i animalnog porekla su jedan od mogućih izvora kontaminacije namirnica ovom bakterijom, što se posebno odnosi na prehrambene proizvode koji prolaze minimalni proces obrade. Međutim, poslednjih godina sve više se ističe značaj postprocesne kontaminacije, nastale kao rezultat kontakta prehrambenih proizvoda sa kontaminiranim površinama u pogonima prehrambene industrije, na kojima ova bakterija može u formi biofilma opstati mesecima, pa čak i godinama. Uprkos skoro opšte prihvaćenom stavu da Listeria monocytogenes formira biofilm, malo je mikroskopskih dokaza koji to potvrđuju. U ovom radu ispitana je sposobnost formiranja biofilma kod 14 sojeva Listeria monocytogenes različitog porekla. Biofilmovi su formirani na površini nerđajućeg čelika za sedam dana inkubacije u tripton soja bujonu sa dodatkom 0.6% kvaščevog ekstrakta na temperaturi od 25ºC. Formirane strukture pregledane su skening elektronskom mikroskopijom. Rezultati pregleda potvrđuju da među testiranim sojevima Listeria monocytogenes postoje značajne razlike u sposobnosti da formiraju biofilm pod korišćenim uslovima ispitivanja. Sedam od 14 testiranih sojeva Listeria monocytogenes nije formiralo biofilm, već su se njihove ćelije kao pojedinačne rasporedile po površini nerđajućeg čelika. Sojevi koji su procenjeni kao 'biofilm producers' formirali su strukture različitog izgleda, od uniformnog, konfluentnog monosloja bakterijskih ćelija do pojedinačnih krupnih, trodimenzionalnih ćelijskih agregata. Svi ispitani sojevi su slabo produkovali ekstracelularnu polimeričnu supstanciju.",
publisher = "Univerzitet u Beogradu - Fakultet veterinarske medicine, Beograd",
journal = "Acta Veterinaria-Beograd",
title = "Scanning electron microscopy of Listeria monocytogenes biofilms on stainless steel surfaces, Skening elektronska mikroskopija biofilmova sojeva Listeria monocytogenes na nerđajućem čeliku",
volume = "59",
number = "4",
pages = "423-435",
doi = "10.2298/AVB0904423M"
}
