Biofilm forming ability of Salmonella enteritidis in vitro
2015
Čabarkapa, Ivana (Institute of Food Technology, Novi Sad (Serbia)) | Škrinjar, Marija (Faculty of Technology, Novi Sad (Serbia)) | Lević, Jovanka (Institute of Food Technology, Novi Sad (Serbia)) | Kokić, Bojana (Institute of Food Technology, Novi Sad (Serbia)) | Blagojev, Nevena (Faculty of Technology, Novi Sad (Serbia)) | Milanov, Dubravka (Scientific Veterinary Institute Novi Sad, Novi Sad (Serbia)) | Suvajdžić, Ljiljana (Faculty of Medicine, Novi Sad (Serbia). Department of Pharmacy)
Salmonella enterica serotype Enteritidis is an important alimentary pathogen that recently gained special attention due to the ability of a large number of strains to form biofi lms. Qualitative testing of biofi lm forming ability was performed by observing the morphotype of the colonies on Congo Red agar and by conducting the pellicle test, while quantitative testing was carried out by Cristal violet assay on microtiter plates. A total of 14 isolates of S.Enteritidis were tested for biofi lm forming ability, while Salmonella Enteritidis ATTC 13076 was used as the reference strain. Based on the morphotype of colonies cultivated on Congo Red agar at 25°C incubation temperature, among tested isolates three morphotypes were detected – red, dry and rough (rdar), brown, dry and rough (bdar) and smooth and white (saw). Half of the tested isolates demonstrated rdar morphotype. All isolates that showed a specifi c morphotype at this incubation temperature also formed the corresponding type of pellicle at the air-liquid interface. Additionally, comparing OD (optical density) values obtained by crystal violet test between groups of isolates that represent one of the three detected morphotypes (rdar, bdar and saw), statistically signifi cant differences were detected. Based on OD values obtained by crystal violet test at both applied incubation temperatures, isolates were classifi ed into three categories, regarding their ability to form biofi lms: strong, moderate and weak biofi lm producers. By comparing the amounts of the biofi lms formed after 48h at 25°C and 37°C, statistically signifi cant differences were noted (P<0.05). In this research we presented micrographs and a reconstruction of three- dimensional projections of biofi lm developing phases of rdar morphotype isolates, which were obtained using confocal laser scanning microscopy.
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