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Microbial Utilization of Arabinogalactan and Effects on Human Gut Microbiota in Response to Bifidobacteria Supplementation

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Title: Microbial Utilization of Arabinogalactan and Effects on Human Gut Microbiota in Response to Bifidobacteria Supplementation
Author: Wang, Yan
Department: Department of Food Science
Program: Food Science
Advisor: LaPointe, Gisèle
Abstract: Arabinogalactan (AG) may improve the abundance of bifidobacteria and the concentration of butyrate in the gut. However, bifidobacteria prefer oligosaccharide utilization, thus most bifidobacteria are unable to utilize AG directly. Therefore, AG utilization by bifidobacteria requires the contribution of other gut bacteria. A better understanding of AG degradation by gut bacteria, and the interaction between bifidobacteria and other intestinal bacteria during AG fermentation is required. This research determined AG-degrading enzymatic functions from Bifidobacterium longum subsp. longum NCC 2705 and Bacteroides caccae ATCC 43185, and investigated metabolic interaction between these strains in the presence of AG. Moreover, the response of stabilized human fecal microbiota to B. longum subsp. longum BB536 supplementation and fermentation of AG versus starch was compared in the Twin Mucosal Simulator of the Human Intestinal Microbial Ecosystem (TWIN-M-SHIME). The endo β-1,3/1,6-galactanases are the main enzymes for degrading the backbone of AG. These enzyme activities from both B. longum NCC 2705 and Bac. caccae ATCC 43185 strains were hindered by the arabinosyl side chains, which could not be degraded by extracellular α–arabinofuranosidase and/or β-arabinopyranosidase enzymes from both strains. These results show why the breakdown of AG by B. longum NCC 2705 and Bac. caccae ATCC 43185 is limited in monoculture. In coculture, the growth of B. longum NCC 2705 can be stimulated by the partial breakdown products from AG that were released by Bac. caccae ATCC 43185. However, the growth and metabolism of Bac. caccae ATCC 43185 were inhibited by low pH due to the metabolism of B. longum NCC 2705. Therefore, the cooperation between bifidobacteria and Bacteroides species may not take place in the proximal colon where low pH conditions occur. In the TWIN-M-SHIME, fermentation of AG significantly increased the concentration of total short chain fatty acids, and the abundance of luminal Faecalibacterium prausnitzii. The combination of B. longum BB536 with AG stimulated butyrate production and increased the abundance of both luminal and mucosal F. prausnitzii in the transverse colon. These results suggest that combination of a potential prebiotic AG with B. longum BB536 could exert a beneficial synbiotic effects on human gut health through butyrate production.
URI: https://hdl.handle.net/10214/23514
Date: 2020-11
Rights: Attribution-NonCommercial-NoDerivatives 4.0 International
Terms of Use: All items in the Atrium are protected by copyright with all rights reserved unless otherwise indicated.
Related Publications: Wang, Y.; LaPointe, G. Arabinogalactan Utilization by Bifidobacterium longum subsp. longum NCC 2705 and Bacteroides caccae ATCC 43185 in Monoculture and Coculture. Microorganisms 2020, 8, 1703, doi:10.3390/microorganisms8111703.
Embargoed Until: 2021-11-30


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Attribution-NonCommercial-NoDerivatives 4.0 International Except where otherwise noted, this item's license is described as Attribution-NonCommercial-NoDerivatives 4.0 International