Cell surface-associated compounds of probiotic lactobacilli sustain the strain-specificity dogma

•Efficacy of probiotic lactobacilli is highly strain-specific.•Peptidoglycan and lipoteichoic acid are ligands with established host receptors.•CPS and wall teichoic acid impact on host responses via shielding of ligands.•Glycosylated proteins: a new class of ligands for glycan-recognizing receptors.•Structural differences in effector molecules sustain strain-specific efficacy.

Probiotic lactobacilli can positively impact on the health status of targeted (diseased) populations but efficacy depends strongly on the strain employed and the molecular basis for this phenomenon is poorly understood. This review discusses the current state-of-the-art in the field of molecular probiotic-host interactions, focusing on subtle strain-specific differences in the biochemical characteristics of cell surface-associated probiotic ligands and the consequences thereof for the immune responses elicited. This research is bound to enhance our understanding of strain-specificity in relation to probiotic functionality and will allow molecular science-based design of screening and characterization assays targeted to improved selection of probiotic candidate strains. Moreover, identified bioactive effector molecules could be isolated or produced for administration in a more pharmacological regime.