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Author(s): Ioannis Iliadis
Aikaterini Daskalopoulou
Manuel Simões
Efstathios Giaouris
Title: Integrated combined effects of temperature, pH and sodium chloride concentration on biofilm formation by Salmonella enterica ser. Enteritidis and Typhimurium under low nutrient food-related conditions
Issue Date: 2018
Abstract: Salmonella enterica is a major foodborne bacterial pathogen. This forms biofilms on surfaces and persists, depending on the strain and the environment. The integrative interaction of temperature (T; 13-39 °C), pH (5-8)and sodium chloride (NaCl) concentration (0.5-8.5%) on biofilm formation by two S. enterica strains (ser.Enteritidis and Typhimurium) was here evaluated under low nutrient conditions. This was achieved using response surface methodology to model the combined effect of each factor on the response, through mathematicalquadratic fitting of the outcomes of a sequence of designed experiments. These last were executed by incubatingstainless steel coupons carrying sessile bacteria, for 24 h, in 1:10 diluted tryptone soya broth, under 15 differentcombinations of three independent factors (T, pH and NaCl). For each strain, a second order polynomial model,describing the relationship between biofilm formation (log CFU/cm2) and the factors (T, pH and NaCl), wasdeveloped using least square regression analysis. Both derived models predicted the combined influences ofthese factors on biofilm formation, with agreement between predictions and experimental observations(R2 ≥ 0.96, P ≤ 0.0001). For both strains, the increase of NaCl content restricted their sessile growth, whileunder low salinity conditions (NaCl < 4%) biofilm formation was favored as pH increased, regardless of T.Interestingly, under low salt content, and depending on the strain, biofilm formation was either favored orhindered by increasing T. Thus, 34.5 and 13 °C were the T predicted to maximize biofilm formation by strainsEnteritidis and Typhimurium, respectively, something which was also experimentally verified. To sum, thesemodels can predict the interactive influences of crucial food-related factors on biofilm growth of a significantfoodborne pathogen towards the efforts to limit its persistence in food industry.
Document Type: Artigo em Revista Científica Internacional
Rights: restrictedAccess
Appears in Collections:FEUP - Artigo em Revista Científica Internacional

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