Influence of disaccharide structure on prebiotic selectivity in vitro

Area of Science:

• Microbiology
• Carbohydrate Chemistry
• Gut Microbiome Research

Background:

• Understanding carbohydrate fermentation by gut microbiota is crucial for developing prebiotics.
• Existing methods often require large sample quantities, limiting research on rare carbohydrates.

Purpose of the Study:

• To validate a micro-scale in vitro fermentation method for assessing carbohydrate structure-function relationships.
• To investigate the impact of glycosidic linkages and monosaccharide composition on disaccharide fermentation selectivity.
• To establish a prebiotic index (PI) for evaluating carbohydrate prebiotic potential.

Main Methods:

• Validation of a 7 mg carbohydrate in vitro fermentation assay against a 1.5 g pH-controlled batch culture.
• Fermentation of various disaccharides using fecal bacteria in basal medium.
• Calculation of a Prebiotic Index (PI) based on microbial fermentation patterns.

Main Results:

• Disaccharides with 1-2, 1-4, and 1-6 linkages, such as kojibiose and sophorose, exhibited high PI scores.
• Mannose-containing disaccharides generally yielded low PI, linked to shifts in bacterial populations (decreased Bifidobacteria/Lactobacilli, increased Bacteroides).
• The validated method accurately reflected fermentation selectivity based on carbohydrate structure.

Conclusions:

• The micro-scale in vitro fermentation method is effective for obtaining structure-function information on limited carbohydrate samples.
• Carbohydrate structure, particularly glycosidic linkages, significantly influences gut microbial fermentation and prebiotic potential.
• Findings may enable predictive understanding of carbohydrate fermentation by the human gut microflora.