(P27-008-24) Diverse Gut Microbiomes From Healthy Adult Consumers of Fruits and Vegetables Demonstrate Fiber-Specific and Donor-Specific Fermentation

Objectives: Determine the fermentation capability of gut microbiomes with diverse carbohydrate active enzyme (CAZyme) capacity in response to diverse dietary fibers.

Methods: Fecal samples were collected from 18 healthy adults who reported consuming at least 5 different fruits and vegetables daily. DNA extracted from these samples was sequenced and analyzed. Fecal samples from the 5 adults with the most diverse carbohydrate active enzyme (CAZyme) capacity were fermented with 7 different fibers selected for their unique monosaccharide profiles—banana, kale, a 13 bean soup, flax, coconut flour, MS Prebiotic (resistant starch supplement) and Sunfiber (guar gum supplement)—for 72 hours. DNA, total/free monosaccharides, and short chain fatty acids (SCFAs) from fermentations were measured.

Results: The largest changes in monosaccharides and SCFAs occurred in the first 24 hours of fermentation. Bacterial diversity decreased the most with MS Prebiotic and the least with kale. Total SCFA, acetate, and propionate production was highest with flax, least with coconut flour; butyrate was highest with MS Prebiotic, lowest with coconut flour; lactate production was highest for MS Prebiotic, lowest with coconut flour. Samples from three subjects were more responsive than the other two, with higher Bifidobacterium and lower Prevotella in the responders. Self-organizing maps revealed 9 fermentation patterns among the 35 fermentation experiments with fiber-specific and donor-specific effects on the extent of fermentation in the first 24 hrs ranging from limited primary degradation (liberated monosaccharides) to little change in microbial diversity to robust production of SCFAs. Across all subjects and fibers, bacterial abundance at 24 hours correlated with the amount of fermentation with Bifidobacteriaceae, Butyricicoccaceae, and Ruminococcaceae with the highest fermentation down to Clostridiaceae, Enterococcaceae, and Eggerthellaceae with the lowest fermentation.

Conclusions: Even frequent consumers of fruits and vegetables with diverse CAZyme repertoires demonstrate variable capacity for fiber fermentation, depending on the fiber and the presence of specific bacterial taxa. The consumption of five fruits and/or vegetables per day does not ensure that the consumer’s gut microbiome is capable of fermenting diverse fibers.

Funding Sources: NIH and USDA ARS