Regulation and expression of candidate genes involved in prebiotic fibre utilization in Lactobacillus plantarum

Probiotics are live microorganisms that when administered in adequate amounts confer a health benefit to the consumer. Prebiotics are non-digestible food ingredients that beneficially affect the host’s health through selective stimulation of growth and/or activity of various non-pathogenic microorganisms present in the host gastrointestinal (GI) tract. The concept of “synbiotics”, introduced in 1995, was defined as “mixtures of probiotics and prebiotics that beneficially affect the host by improving the survival and implantation of live microbial dietary supplements in the GI tract, by selectively stimulating the growth and/or by activating the metabolism of one or a limited number of heal-promoting bacteria, thus improving host welfare (Gibson & Roberfroid, J Nutr, 1995 125:1401-1412). However, in a synbiotic concept the prebiotic compound may not necessarily elicit a health benefit by exclusively modulating the endogenous microbiome, but may also achieve this by enhancing the viability and activity of the administered probiotic. Beneficial effects of probiotics can be limited when the intestinal delivery of live bacteria is insufficient or too short-lived to elicit the required responses in the intestinal mucosa. Prebiotics could provide a substrate for growth of probiotics in situ while residing in the GI tract, and thereby increase and/or extend the abundance and persistence of these health-promoting bacteria, to enhance their capacity to elicit their health promoting effects.

The motivation in this research lies in the potential to optimize probiotic delivery in the host through the simultaneous administration of prebiotic fibres that would actively increase the activity and/or growth of the probiotic. To this end, candidate probiotic strains are screened in vitro for their capacity to utilize specific prebiotic substrates for growth, to identify optimal synbiotic concepts for in situ delivery of the target probiotics. The efficacy of such synbiotic mixtures will we evaluated in the context of the dietary regime in which they are administered using animal model studies. In addition, the intestinal microbiota signatures associated with dietary regimes and modulated synbiotic efficacy will be investigated in these models to decipher the influence of the endogenous intestinal microbiota in probiotic colonization and persistence.