Genes and Molecules of Lactobacilli Supporting Probiotic Action

Abstract

Lactobacilli have been crucial for the production of fermented products for centuries. They are also members of the mutualistic microbiota present in the human gastrointestinal and urogenital tract. Recently, increasing attention has been given to their probiotic, health-promoting capacities. Many human intervention studies demonstrating health effects have been published. However, as not all studies resulted in positive outcomes, scientific interest arose regarding the precise mechanisms of action of probiotics. Many reported mechanistic studies have addressed mainly the host responses, with less attention being focused on the specificities of the bacterial partners, notwithstanding the completion of Lactobacillus genome sequencing projects, and increasing possibilities of genomics-based and dedicated mutant analyses. In this emerging and highly interdisciplinary field, microbiologists are facing the challenge of molecular characterization of probiotic traits. This review addresses the advances in the understanding of the probiotic-host interaction with a focus on the molecular microbiology of lactobacilli. Insight into the molecules and genes involved should contribute to a more judicious application of probiotic lactobacilli and to improved screening of novel potential probiotics.

Lectin Microarray Reveals Binding Profiles of Lactobacillus casei Strains in a Comprehensive Analysis of Bacterial Cell Wall Polysaccharides

“…Lectin microarray preparation and lectin specificities. The lectin microarray was prepared as previously described (21)(22)(23). Briefly, 44 lectins were dissolved at a concentration of 0.5 mg/ml in a spotting solution (Matsunami Glass) and spotted onto epoxysilane-coated glass slides (Schott) in triplicate using a noncontact microarray printing robot (MicroSys4000; Genomic Solutions).…”

“…For example, soluble proteins produced by probiotic bacteria are known to regulate survival and growth of intestinal epithelial cells (11,18,30). Although the cell surface components of LAB such as S-layer proteins, LTA, WTA, and PSs are proposed to be immune modulators (21), the active components directly involved in immune modulation and the molecular nature of these recognition processes are largely unknown.…”

“…In the light of recent research on the role of bacterial cell surface structures/components in probiotic or symbiotic action (21), PSs from each bacterial cell wall could have individual and unique roles which are more important than has ever been assumed (4,19,22,46). As described in some reports concerning Bacteroides fragilis polysaccharides (7,8,27), bacterial cells have different impacts on host cells, even when various mutants having defects in different predictive polysaccharide biosynthesis genes or deletions showed different immune-modulating effects on cultured splenocytes and T cells.…”

Comparative genomic analysis of Lactobacillus rhamnosus GG reveals pili containing a human- mucus binding protein

“…Based on their health-promoting effects, these bacteria are commonly marketed as probiotics (1)(2)(3). One postulated feature considered indispensable for some probiotic lactobacilli is adherence to human intestinal tissues, which may promote a variety of specific interactions with the host (4)(5)(6). Despite many studies demonstrating the adherent properties of lactobacilli, the molecular mechanisms governing these host-microbe interactions are only beginning to emerge as comparative and functional analyses of their genome sequences progress (7,8).…”

Evaluation of bifidobacterial adhesion to acidic sugar chains of porcine colonic mucins

“…5) Bacterial adhesion to the mucosal surface through mucus layers is an important prerequisite for the colonization of probiotics in the intestinal lumen and provides a competitive advantage in this ecosystem. 6) Mucus layers consist mainly of gel-forming mucin, which are secreted by goblet cells on the intestinal mucosa. 7) The mucus layer is considered to be the first line of defense against bacteria in the intestinal tract and serves as the initiation surface for host-microbe interactions.…”