Effects of environmental and genetic factors on biofilm formation of various Salmonella serotypes

Biofilm formation by Salmonella spp. poses significant challenges across environmental, public health, industrial, and medical sectors, with its capacity to form biofilms influenced by environmental and genetic factors. The present study aimed to identify the biofilm morphotypes of Salmonella serotypes (n=120) and investigate the effects of environmental factors (temperature, pH, and salt concentration) by conventional analysis and genetic factors (csrB, csrC, fimA, and fimI genes) on biofilm formation by molecular analysis. Five different serotypes of Salmonella enterica subsp. enterica were used in this study, including serotype Infantis (S. Infantis) (n=100), serotype Enteritidis (S. Enteritidis) (n=5), serotype Hadar (S. Hadar) (n=5), serotype Kentucky (S. Kentucky) (n=5), and serotype Typhimurium (S. Typhimurium) (n=5). Biofilm formation capacities were examined using the microtiter plate method, while the presence of biofilm formation genes were assessed by polymerase chain reaction (PCR) analysis. The analyses indicated that red, dry, and rough (rdar) was the predominant morphotype in S. Infantis (96%), S. Enteritidis (100%), S. Kentucky (100%), and S. Typhimurium (100%) serotypes, while brown, dry, and rough (bdar) was found in all S. Hadar (100%) serotypes. Under suitable conditions, at 20 °C, pH 6.6, and 0.5% salt concentration, the optimal biofilm formation time was 72 hours for all serotypes, except for S. Typhimurium. No isolates formed biofilms at pH 4.5 or salt concentrations above 0.5%. The biofilm formation genes csrB, csrC, fimA, and fimI, were found in all isolates (100%). This study revealed the biofilm diversity in Salmonella spp. isolates of poultry origin in Türkiye and the effects of environmental factors on biofilm formation. The findings may guide interventions aimed at eliminating Salmonella spp. from surfaces by preventing biofilm formation.