Pectins are structural, plant cell wall polysaccharides that are consumed as part of a diet containing fruits and vegetables. They are heterogeneous polysaccharides with 3 structural domains, homogalacturonan, and 2 branched rhamnogalacturonan regions (RG-I and RG-II). The number of carboxyl groups that can be esterified with methyl groups determines the type of pectin and their degree of esterification. Inside the gastrointestinal tract, pectin cannot be metabolized by the mammalian cells lining the small intestine but is fermented by the gut microbiota of the colon to produce short chain fatty acids (SCFA) and other metabolites. Fermentation of pectin occurs due to the release of carbohydrate-active enzymes from the commensal species from genus Bacteroides and Prevotella. In addition, enzymes such as lyase, methylesterase, and acetylesterase are produced by the gut microbes to facilitate degradation of pectin. A number of studies have been performed looking at the effect of pectin on the gut microbiota. However, the results have been inconsistent, most likely due to differences in the chemical structures of the pectin used. In addition, these experiments were performed using short-term, batch cultures without the development of a mature gut microbial community. Here, we evaluated the effects of pectin, with varying degrees of esterification, on a stable and mature gut microbiota in vitro. Changes to the gut microbiota community structure and function were determined using advanced DNA sequencing and metabolomics. The results of this study provide information on how the different pectins modulate the gut microbiota and contribute to our understanding on how pectin structure and degree of esterification may impact this interaction.

Comparative analysis of changes to the human gut microbiota community that occur in response to pectins with variable degrees of methoxylation

ACS Fall 2020 Virtual Meeting

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