Finding the molecules that make probiotics work
Probiotics constitute an important growth market for the food industry. The industrial importance of these healthpromotingbacteria has led to significant efforts to identify bacterial effector molecules, responsible for the observed effects inthe consumer. Several genomes of probiotic bacteria were determined over the last decade, allowing (post) genomic acceleration of the quest to uncover molecular host-probiotic interactions. This review describes the effector molecules identifiedin probiotic lactobacilli, focusing on the model probiotic organism Lactobacillus plantarum WCFS1. Despite the fact that the workdescribed here was performed in different mammalian gastrointestinal model systems, the bacterial responses identifieddisplayed a partial overlap, suggesting a diet-, host-, and microbiota-independent core response in L. plantarum. Thecorresponding molecules are robust effector molecules responsible for the effective (probiotic) functionality of this LAB in situ. Inaddition, fermentation and harvesting conditions of this probiotic strain strongly influenced the immune modulation observed inthe host. This review will also discuss the strategic initiatives employed to further expand the current knowledge on probiotic effector molecules.