In vitrofermentation of commercial α-gluco-oligosaccharide by faecal microbiota from lean and obese human subjects

Abstract

The fermentation selectivity of a commercial source of a-gluco-oligosaccharides (BioEcolians; Solabia) was investigated in vitro. Fermentation by faecal bacteria from four lean and four obese healthy adults was determined in anaerobic, pH-controlled faecal batch cultures. Inulin was used as a positive prebiotic control. Samples were obtained at 0, 10, 24 and 36 h for bacterial enumeration by fluorescent in situ hybridisation and SCFA analyses. Gas production during fermentation was investigated in non-pH-controlled batch cultures. a-Gluco-oligosaccharides significantly increased the Bifidobacterium sp. population compared with the control. Other bacterial groups enumerated were unaffected with the exception of an increase in the Bacteroides -Prevotella group and a decrease in Faecalibacterium prausnitzii on both a-gluco-oligosaccharides and inulin compared with baseline. An increase in acetate and propionate was seen on both substrates. The fermentation of a-gluco-oligosaccharides produced less total gas at a more gradual rate of production than inulin. Generally, substrates fermented with the obese microbiota produced similar results to the lean fermentation regarding bacteriology and metabolic activity. No significant difference at baseline (0 h) was detected between the lean and obese individuals in any of the faecal bacterial groups studied.Key words: Gluco-oligosaccharides: Prebiotics: Obese subjectsIt is now well established that the composition of the colonic microbiota can be modified by the introduction of prebiotics to improve or maintain host health (1) . The efficacy of a prebiotic can be evaluated by in vitro batch-culture fermentation systems which have been compared and validated against human and animal in vivo data (2) . Batch-culture fermentation systems provide a simple, rapid and inexpensive method of evaluating the prebiotic potential of carbohydrates.To date, the majority of studies on prebiotics have focused on inulin, fructo-oligosaccharides and galacto-oligosaccharides due to their selective fermentation by bifidobacteria and history of safe commercial use. Nevertheless, there are potential prebiotic oligosaccharides still under investigation, such as a-gluco-oligosaccharides. These gluco-oligosaccharides are selectively metabolised by Bifidobacterium, Lactobacillus and Bacteroides but are poorly metabolised by potentially pathogenic bacteria such as enterobacteria and Clostridium (3) . Even though they exhibit promising characteristics, the evidence is not sufficient to classify them as prebiotics presently (4) . All studies to date have been carried out by culture-dependent methods, which are not reliable for the analysis of complex bacterial samples. Therefore, further investigation using culture-independent (DNA-based) methods is needed to verify these initial findings.The human gut microbiota is dominated by two major phyla, the Bacteroidetes and Firmicutes (5) . A study has observed that genetically obese mice had a higher proportion of Firmicutes relative to Bacteroidetes ...

Recent developments in prebiotics to selectively impact beneficial microbes and promote intestinal health

“…They can also be branched in structure. Commercial GlOS products have been shown to be selective for bifidobacteria and bacteroides with a decrease in Faecalibacterium prausnitzii using in vitro faecal batch cultures [38] and bacterial counting using group-specific fluorescent gene probes. Whilst an increase in bifidobacteria would be considered as a health-positive change, a decrease in F. prausnitzii might not be desirable as this species is attracting interest as an anti-inflammatory component of the gut microbiota [39 ].…”

Obesity prevention of synthetic polysaccharides in high-fat diet fed C57BL/6 mice

“…The tubes were kept at 4°C for approximately 2 h to dissolve the substrates before initiating fermentations. The inoculate were prepared as described by Sarbini, Kolida, Gibson, and Rastall (2012). Before inoculation, the tubes were pre-warmed in a 37°C water bath for 30 min, and then each vessel was inoculated with 1 mL of fresh faecal slurry with the upper space of each tube filled with pure N2 under normal pressure.…”

Powder lemon juice containing oligosaccharides obtained by dextransucrase acceptor reaction synthesis and dehydrated in sprouted bed

“…Sarbini et al (2013) reported that commercial α-gluco-oligosaccharides significantly increased the Bifidobacterium sp. population compared with the control (inulin) and the fermentation of α-glucooligosaccharides produced less gas than inulin.…”