Metabolic Activity Decreases with Polysaccharide Molecular Weight

Importance: Polysaccharides are complex molecules that are commonly found in our diet. While humans lack the ability to degrade many polysaccharides, their intestinal microbiota contain bacterial commensals that are versatile polysaccharide utilizers. The gut commensal dedicates roughly 20% of their genomes to the expression of polysaccharide utilization loci for the broad range utilization of polysaccharides. Although it is known that different polysaccharide utilization loci are dedicated to the degradation of specific polysaccharides with unique glycosidic linkages and monosaccharide compositions, it is often overlooked that specific polysaccharides may also exist in various molecular weights. These different physical attributes may impact their processability by starch utilization system-like systems, leading to differing growth rates and nutrient-sharing properties at the community level. Therefore, understanding how molecular weight impacts utilization by gut microbe may lead to the potential design of novel precision prebiotics.