The Critical Roles of Polysaccharides in Gut Microbial Ecology and Physiology

Abstract

The human intestine harbors a dense microbial ecosystem (microbiota) that is different between individuals, dynamic over time, and critical for aspects of health and disease. Dietary polysaccharides directly shape the microbiota because of a gap in human digestive physiology, which is equipped to assimilate only proteins, lipids, simple sugars, and starch, leaving nonstarch polysaccharides as major nutrients reaching the microbiota. A mutualistic role of gut microbes is to digest dietary complex carbohydrates, liberating host-absorbable energy via fermentation products. Emerging data indicate that polysaccharides play extensive roles in host-gut microbiota symbiosis beyond dietary polysaccharide digestion, including microbial interactions with endogenous host glycans and the importance of microbial polysaccharides. In this review, we consider multiple mechanisms through which polysaccharides mediate aspects of host-microbe symbiosis in the gut, including some affecting health. As host and microbial metabolic pathways are intimately connected with diet, we highlight the potential to manipulate this system for health.

Complex dietary polysaccharide modulates gut immune function and microbiota, and promotes protection from autoimmune diabetes

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“…There are multiple roles that CPS could play in the fitness of intestinal symbiotic microbes (reviewed in Porter and Martens, 2017). First, bacteria may optimize cell energy expenditures by synthesizing CPS similar in composition to sugars that the bacterium is metabolizing.…”

microRNA regulation in an ancient obligate endosymbiosis

“…Symbioses, mutually beneficial interactions between species, are important determinants of phenotype, the ability of organisms to digest food, heal wounds and reproduce (Dedeine et al., ; Douglas, ; Engelstadter & Hurst, ; Grice & Segre, ; Iwase et al., ; Porter & Martens, ; Yong, ). While the last decade witnessed great progress across the tree of life in elucidating the roles that symbionts play in ecology, evolution and organismal health, an outstanding compelling challenge in symbiosis research concerns identification and characterization of the mechanisms of host/symbiont integration (Shigenobu & Wilson, ).…”