BIOFILM FORMATION OF Salmonella sp IN DIFFERENT CULTURE MEDIA

FLORENCIA COLOCHO; GABRIELA ISABEL FAVIER; MARTIN MAYER; CARLOS RODOLFO PUNGITORE; CECILIA S. M. LUCERO ESTRADA

Mendoza

Congreso; XXX Reunión Científica Anual de la Sociedad de Biología de Cuyo. Sociedad Biología de Cuyo; 2022

Sociedad de Biolog{ia de Cuyo

Salmonella spp. is mostly involved in foodborne illnesses worldwide. Approximately 2,500 Salmonella serotypes have been identified, the majority of which may adapt to several animal hosts, including humans. Furthermore, the persistence of foodborne pathogens in biofilms has also been reported, mainly on food contact surfaces, affecting product quality, quantity, and safety. In the meat industry, bacterial biofilms are a major concern due to accumulation in areas difficult to sanitize, leading to cross-contamination and food spoilage. Several studies have reported the influence of biofilm formation on the survival of bacteria on both biotic and abiotic surfaces, and the resistance of bacterial biofilms to sanitizers. Different serotypes of Salmonella attached and formed biofilms in different quantities on different abiotic surfaces. The objective of this work was to evaluate the glucose concentration in order to find the most suitable medium for biofilm formation. Thirteen Salmonella strains of two serotypes were studied: three Salmonella Typhimurium and 10 Salmonella Enteritidis. These strains were culture for 24 h at 37°C in 96 well polystyrene plates; afterward, planktonic cells were measure at 650 nm, and biofilm formation was determined by the crystal violet (CV) technique and measure at 550 nm. Three media were evaluated: Luria Bertani broth (LB, without glucose), triptycase soy broth (TSB, 0.25% glucose); and TSB supplemented with 0.25% glucose (TSBG, 0.5% glucose).The mean absorbance obtained from triplicate readings was used to determine the final optical density of each strain (ODf), which was compared with that of the negative control (ODn). The isolates were categorized into non-biofilm-forming isolates (NF) when ODf ≤ ODn, weakly biofilm-forming (WBF) when ODn < ODf ≤ 2×ODn, moderate biofilm-forming (MBF) when 2×ODn < ODf ≤ 4×ODn, or strong biofilm-forming (SBF) when 4×ODn < ODf. With the three media, all strains were able to forma biofilm under these culture conditions. The medium that favored the biofilm formation for both Salmonella serotypes was TSB as nine of the 13 studied strains were SBF and the other four strains were MBF. With LB, eight strains were SBF, four strains were MBF, and one strain was WFB. On contrary, with TSBG seven strains were WBF, four strains were MBF and two strains were SBF. These results demonstrate that the glucose concentration into the culture medium influence in the capacity of Salmonella spp strains to form biofilm and that a 0.25% favored this phenotype, which would represent a greater virulence in these regional Salmonella strains.