Biofilm-producing abilities of Salmonella strains isolated from Turkey

In the present study the biofilm-forming characteristics of 99 serotyped (DMC strains) and 41 genus level-identified (IS strains) Salmonella strains originating from Turkey were investigated. The strains were selected based on their ability to show the biofilm morphotype on Congo red agar plates. In addition, all strains were evaluated with regard to properties related to forming pellicle structures, physical differences of pellicles, any changes in the media associated with the formation of pellicles, and the presence of cellulose within the formed biofilm matrix as determined using 366 nm UV light. The Salmonella Typhimurium DMC4 strain was the best producer of biofilm grown on polystyrene microtiter plates (optical density at 595 nm: 3.418). In subsequent experiments industrial process conditions were used to investigate different morphotyped Salmonella strains’ biofilm-forming capability on stainless steel, a commonly preferred surface for the food industries, and on polystyrene surfaces. The effect of other important industrial conditions, such as temperature (5, 20, 37°C), pH (4.5, 5.5, 6.5, 7.4) and NaCl concentration (0.5, 1.5, 5.5, 10.5%) on the production of biofilm of the different morphotyped Salmonella strains (DMC4; red, dry and rough morphotyped S. Typhimurium, DMC12; brown, dry and rough morphotyped S. Infantis, DMC13; pink, dry and rough morphotyped S. subsp. Roughform) were also assessed. On the other hand, pH values exhibited variable effects on biofilm-forming features for different Salmonella strains on both polystyrene and stainless steel surfaces.