Fecal microbiota composition affects in vitro fermentation of rye, oat, and wheat bread

Area of Science:

• Microbiology
• Nutritional Science
• Gastroenterology

Background:

• Gut microbiota ferment dietary fiber, producing short-chain fatty acids (SCFA).
• Fermentation outcomes depend on the dietary fiber source and the composition of the gut microbiota.
• Understanding these interactions is crucial for gut health and nutrition.

Purpose of the Study:

• To investigate how two distinct fecal microbial compositions influence the in vitro fermentation of oat, rye, and wheat breads.
• To analyze short-chain fatty acid (SCFA) production, dietary fiber degradation, and microbial community shifts.

Main Methods:

• Utilized an in vitro fermentation model with two human fecal donors exhibiting different microbial profiles (Donor I: Bacteroides/Escherichia/Shigella; Donor II: Prevotella/Subdoligranulum).
• Bread substrates (oat, rye, wheat) were enzymatically digested prior to fermentation.
• Monitored SCFA production, dietary fiber degradation, pH changes, and microbiota composition shifts over 24 hours.

Main Results:

• Microbiota composition shifted during fermentation.
• Short-chain fatty acid (SCFA) levels varied between donors, with higher butyrate production observed in Donor II, particularly with rye.
• Dietary fiber degradation was more extensive with the microbiota from Donor II, especially when utilizing rye as a substrate.

Conclusions:

• Distinct gut microbiota compositions exhibit different capacities for dietary fiber fermentation and substrate utilization.
• Microbiota composition, specifically the abundance of genera like Subdoligranulum, plays a key role in butyrate production and fiber breakdown.
• These findings highlight the personalized impact of gut microbiota on nutrient metabolism from dietary fibers.