<p>It is well known that colonic microbiota is influenced by both
intrinsic and extrinsic factors; out of all these, diet plays a major role. The
traditional human diet has typically been high in overall dietary fiber intake,
due its inherent presence in plant-derived foods. However, over the years,
dietary patterns have transitioned into a low-fiber Westernized diet. This diet
is increasingly implicated in colonic diseases. Dietary fiber consumption is
known to increase microbial diversity, yet the mechanisms are still unclear.
This is partially true because dietary fiber as a category is composed of a
wide variety of structures, which may have divergent effects on the gut
microbiome. The food industry has extracted, isolated, refined and purified
non-digestible carbohydrates and, in some cases, modified them for improved
function, which may influence their interaction with the gut microbiome. This
study was developed in two phases: we first hypothesized that glucans produced
by different processes were structurally distinct and that these fine
structural differences in glucans would govern microbial responses to the
polymers. To test
this hypothesis, we first determined the structural characteristics of the
glucans by gas chromatography and mass spectrometry, which revealed substantial
structural differences among the glucans with respect to size and linkage
patterns, consequently categorizing the glucans by structure (i.e., mixed
linkage α-glucans, resistant maltodextrins, and polydextroses). The second
study involved the <i>in vitro </i>fecal
fermentation of these commercially available soluble glucans which are
uniformly composed of glucose linked into different structural arrangements. We
further hypothesized that each glucan would select for different microbiota and
that there would be glucan-specific general responses across microbiomes. We
were able to identify a variety of idiosyncratic metabolic patterns as well as
differential organisms selecting for specific glucan structures. Although there
were associations with glucan classes at the family level (e.g., <i>Bacteriodaceae </i>and <i>Lachnospiraceae </i>were discriminants of the resistant
maltodextrins and polydextroses respectively),
associations with glucans across individual species within these families varied.
These findings suggest that microbiome responses to structurally distinct
glucans depend upon both fine glucan structure and community context, and
community metabolic phenotypes emerge from the interaction of the two. These
findings are relevant to the food industry as they may enable optimization of
synthesis to generate chemical structures that select for specific organisms
and/or improve overall gut health.</p>
| Identifer | oai:union.ndltd.org:purdue.edu/oai:figshare.com:article/14200382 |
| Date | 06 April 2021 |
| Creators | Arianna D Romero Marcia (10290917) |
| Source Sets | Purdue University |
| Detected Language | English |
| Type | Text, Thesis |
| Rights | CC BY 4.0 |
| Relation | https://figshare.com/articles/thesis/EFFECT_OF_GLUCAN_CHEMICAL_STRUCTURE_ON_GUT_MICROBIOTA_COMPOSITION_AND_FUNCTION/14200382 |
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