Low amounts of dietary fibre increase in vitro production of short-chain fatty acids without changing human colonic microbiota structure

Abstract

This study investigated the effect of various prebiotics (indigestible dextrin, α-cyclodextrin, and dextran) on human colonic microbiota at a dosage corresponding to a daily intake of 6 g of prebiotics per person (0.2% of dietary intake). We used an in vitro human colonic microbiota model based on batch fermentation starting from a faecal inoculum. Bacterial 16S rRNA gene sequence analysis showed that addition of 0.2% prebiotics did not change the diversity and composition of colonic microbiota. This finding coincided with results from a clinical study showing that the microbiota composition of human faecal samples remained unchanged following administration of 6 g of prebiotics over seven days. However, compared to absence of prebiotics, their addition reduced the pH and increased the generation of acetate and propionate in the in vitro system. Thus, even at such relatively low amounts, prebiotics appear capable of activating the metabolism of colonic microbiota.

Construction of a Model Culture System of Human Colonic Microbiota to Detect Decreased Lachnospiraceae Abundance and Butyrogenesis in the Feces of Ulcerative Colitis Patients

“…Previously, the KUHIMM in vitro human colonic microbiota model produced bacterial species numbers and diversity roughly equivalent to those in fecal samples from HS . Initially, the stability of the gut microbiota from four UC patients was monitored in the cultures of KUHIMM until 48 h after inoculation of fecal donors (Figure S1, Supporting Information).…”

“…However, these models do not reflect the complex microbial diversity in UC fecal donors, as shifts in microbial diversity occur during successive culture in multicompartment reactors . We, therefore, developed an in vitro human colonic model using the batch fermentation system (named as the Kobe University Human Intestinal Microbiota Model [KUHIMM]), which simulates the bacterial proportions and diversity of fecal samples from healthy humans as confirmed by next‐generation sequencing (NGS) analysis . The anoxic condition in the KUHIMM was carefully constructed using the defined medium for the growth of anaerobes and constant flushing with anaerobic gas .…”

“…We, therefore, developed an in vitro human colonic model using the batch fermentation system (named as the Kobe University Human Intestinal Microbiota Model [KUHIMM]), which simulates the bacterial proportions and diversity of fecal samples from healthy humans as confirmed by next‐generation sequencing (NGS) analysis . The anoxic condition in the KUHIMM was carefully constructed using the defined medium for the growth of anaerobes and constant flushing with anaerobic gas . This model also simulates the production of SCFAs in fecal donors, enabling evaluation of the effect of prebiotic oligosaccharides and dietary fibers on the colonic microbiota .…”

“…The anoxic condition in the KUHIMM was carefully constructed using the defined medium for the growth of anaerobes and constant flushing with anaerobic gas . This model also simulates the production of SCFAs in fecal donors, enabling evaluation of the effect of prebiotic oligosaccharides and dietary fibers on the colonic microbiota . Thus, the KUHIMM fermentation system is a simple, quick, and noninvasive method useful for studying the condition of the colonic microbiota.…”

In vitro approach to evaluate the fermentation pattern of inulin-rich food in obese individuals

“…Vegetables rich in insoluble fibres in the present study showed greater parameters of fermentation kinetics and higher SCFA production than those obtained for cellulose in an in vitro model. SCFA are recognised fermentation products of great importance for health, and which perform several functions, such as the regulation of absorption of water and minerals, the reduction of the pH of the colon thus inhibiting the development of pathogens present, while promoting the growth of beneficial bacteria (48) . Thus, it should be understood that, the relationships between fermentable carbohydrates and metabolic yield depend on the composition of the microbial community and the metabolic characteristics of each anaerobic bacterium (49) .…”