Diversity of the surface properties of Lactococci and consequences on adhesion to food components.

Bacteria possess surface properties, related to their charge, hydrophobicity and Lewis acid/base characteristics, that are involved in the attachment processes of microorganisms to surfaces. Fermentation bulks and food matrixes are complex heterogeneous media containing various components with different physicochemical characteristics. The aim of the present study was to investigate whether (i) bacteria present in a food matrix, interacted physicochemically at their surface level with the other constituents and (ii) the diversity of bacterial surface properties could result in a diversity of microbial adhesion to components and thus in a diversity of tolerance to toxic compounds. The surface properties of 20 lactic acid bacteria were characterized by the MATS method showing their relatively hydrophilic and various basic characteristics. The results obtained from a set of representative strains showed that (i) the strains with higher affinity for apolar solvents adsorbed more to lipids and hydrophobic compounds, (ii) the more the strains adsorbed to a toxic solvent, the less they were tolerant to this solvent. A diversity of bacterial surface properties was observed for the strains in the same species showing the importance of choosing bacteria according to their surface properties in function of technological objectives.