Effects of different environmental stresses on cell surface hydrophobicity of lactobacilli, bifidobacteria and propionibacteria

Abstract

Background: Probiotic adhesion to intestinal mucosa benefits health and is considered a fundamental property of probiotic bacteria; hydrophobicity is a screening parameter to assess adhesion. This study aimed at evaluating changes in the cell surface hydrophobicity of 10 different functional strains or starter cultures in response to various intrinsic and extrinsic factors. Results: Following an initial screening, pH, temperature, and salt (NaCl) concentration were selected as key variables and combined using a full factorial design. The data were initially analyzed using a two-way ANOVA, followed by a multiple regression analysis. Temperature and pH had a significant effect (P < 0.05), with a positive correlation observed between pH/temperature and hydrophobicity, while NaCl exhibited a negative correlation. In the second step, multiple regression analysis was used to further process the results, confirming the importance of considering interactions between factors, which could either positively or negatively influence cell surface hydrophobicity. Conclusions: Hydrophobicity is strongly species- and strain-dependent; however, some general trends were observed. Specifically, an increase in hydrophobicity was associated with higher temperatures and alkaline pH (pH 8.0), while cell aging had a detrimental effect. These findings highlight the importance of cultural conditions in influencing certain properties of functional microorganisms.