In vitro fermentability of xylo-oligosaccharide and xylo-polysaccharide fractions with different molecular weights by human faecal bacteria

Xylo-oligosaccharides and xylo-polysaccharides (XOS, XPS) produced by autohydrolysis of the fibre from oil palm empty fruit bunches (OPEFB) were purified using gel filtration chromatography to separate the XOS and XPS from the crude autohydrolysis liquor. Six mixed fractions of refined XOS and XPS with average degree of polymerisation (avDP) of 4-64 were obtained. These were characterised in terms of their composition and size by HPLC, MALDI-ToF-MS (selected fractions) and carbohydrate gel electrophoresis (PACE). They were assessed in batch culture fermentations using faecal inocula to determine their ability to modulate the human faecal microbiota in vitro by measuring the bacterial growth, organic acid production and the XOS assimilation profile. The gut microbiota was able to utilise all the substrates and there was a link between the XOS/XPS degree of polymerisation with the fermentation properties. In general, XOS/XPS preparations of lower avDP promote better Bifidobacterium growth and organic acid production

In vitro fermentation properties of pectins and enzymatic-modified pectins obtained from different renewable bioresources

The suitability of artichoke and sunflower by-products as renewable sources of pectic compounds with prebiotic potential was evaluated by studying their ability to modulate the human faecal microbiota in vitro. Bacterial populations and short-chain fatty acid (SCFA) production were measured. Reduction of the molecular weight of artichoke pectin resulted in greater stimulation of the growth of Bifidobacterium, Lactobacillus and Bacteroides/Prevotella, whilst this effect was observed only in Bacteroides/Prevotella for sunflower samples. In contrast, the degree of methylation did not have any impact on fermentability properties or SCFA production, regardless of the origin of pectic compounds. Although further in vivo studies should be conducted, either pectin or enzymatically-modified pectin from sunflower and artichoke by-products might be considered as prebiotic candidates for human consumption showing similar ability to promote the in vitro growth of beneficial gut bacteria as compared to well-recognized prebiotics such as inulin or fructo-oligosaccharides

Recent development of prebiotic research — statement from an expert workshop

A dietary prebiotic is defined as ‘a substrate that is selectively utilized by host microorganisms conferring a health benefit’. Although this definition evolved concomitantly with the knowledge and technological developments that accrued in the last twenty years, what qualifies as prebiotic continues to be a matter of debate. In this statement, we report the outcome of a workshop where academic experts working in the field of prebiotic research met with scientists from industry. The workshop covered three main topics: (i) evolution of the prebiotic concept/definition; (ii) the gut modeling in vitro technology PolyFermS to study prebiotic effects; and (iii) the potential novel microbiome-modulating effects associated with vitamins. The future of prebiotic research is very promising. Indeed, the technological developments observed in recent years provide scientists with powerful tools to investigate the complex ecosystem of gut microbiota. Combining multiple in vitro approaches with in vivo studies is key to understanding the mechanisms of action of prebiotics consumption and their potential beneficial effects on the host

Author Correction: Probiotics and prebiotics in intestinal health and disease: from biology to the clinic (Nature Reviews Gastroenterology & Hepatology, (2019), 16, 10, (605-616), 10.1038/s41575-019-0173-3)

© 2019, Springer Nature Limited. In the original article published online, the Competing Interests statement was incorrect and should have stated the following: M.E.S. declares personal fees related to probiotics from the following entities: California Dairy Research Foundation, Clorox, Danone, Danone USA, Dutch Mill, General Mills, JHeimbach, Kelley Drye & Warren, Kellogg, Kerry, Medscape, Nestle, New Chapter, Pepsico, Pfizer, Pharmavite, Probi, Procter & Gamble, Trouw Nutrition, Visalia Dairy Company, Williams Mullen, Winclove Probiotics and Yakult. D.J.M. declares personal fees for consulting for Bayer and Pharmavite. G.R. declares that he helped develop and commercialize probiotic strains GR-1 and RC-14, but has had no financial interest in them for over 10 years. He is Chief Scientific Officer for Seed, a company producing probiotic products. Over the past 3 years, he has consulted on probiotics with Acerus Pharmaceuticals, Altmann, Chr. Hansen, Danone, KGK Science, Kimberly-Clark, Metagenics and Seed. G.R.G. and R.A.R. declare no competing interests. This error has been corrected in the HTML and PDF versions of the article

Potential of novel dextran oligosaccharides as prebiotics for obesity management through in vitro experimentation

The energy-salvaging capacity of the gut microbiota from dietary ingredients has been proposed as a contributing factor for the development of obesity. This knowledge generated interest in the use of non-digestible dietary ingredients such as prebiotics to manipulate host energy homeostasis. In the present study, the in vitro response of obese human faecal microbiota to novel oligosaccharides was investigated. Dextrans of various molecular weights and degrees of branching were fermented with the faecal microbiota of healthy obese adults in pH-controlled batch cultures. Changes in bacterial populations were monitored using fluorescent in situ hybridisation and SCFA concentrations were analysed by HPLC. The rate of gas production and total volume of gas produced were also determined. In general, the novel dextrans and inulin increased the counts of bifidobacteria. Some of the dextrans were able to alter the composition of the obese human microbiota by increasing the counts of Bacteroides–Prevotella and decreasing those of Faecalibacterium prausnitzii and Ruminococcus bromii/R. flavefaciens. Considerable increases in SCFA concentrations were observed in response to all substrates. Gas production rates were similar during the fermentation of all dextrans, but significantly lower than those during the fermentation of inulin. Lower total gas production and shorter time to attain maximal gas production were observed during the fermentation of the linear 1 kDa dextran than during the fermentation of the other dextrans. The efficacy of bifidobacteria to ferment dextrans relied on the molecular weight and not on the degree of branching. In conclusion, there are no differences in the profiles between the obese and lean human faecal fermentations of dextrans

Probiotics and prebiotics in intestinal health and disease: from biology to the clinic

Probiotics and prebiotics are microbiota-management tools for improving host health. They target gastrointestinal effects via the gut, although direct application to other sites such as the oral cavity, vaginal tract and skin is being explored. Here, we describe gut-derived effects in humans. In the past decade, research on the gut microbiome has rapidly accumulated and has been accompanied by increased interest in probiotics and prebiotics as a means to modulate the gut microbiota. Given the importance of these approaches for public health, it is timely to reiterate factual and supporting information on their clinical application and use. In this Review, we discuss scientific evidence on probiotics and prebiotics, including mechanistic insights into health effects. Strains of Lactobacillus, Bifidobacterium and Saccharomyces have a long history of safe and effective use as probiotics, but Roseburia spp., Akkermansia spp., Propionibacterium spp. and Faecalibacterium spp. show promise for the future. For prebiotics, glucans and fructans are well proven, and evidence is building on the prebiotic effects of other substances (for example, oligomers of mannose, glucose, xylose, pectin, starches, human milk and polyphenols)

Prebiotic supplementation of In Vitro fecal fermentations inhibits proteolysis by gut bacteria, and host diet shapes gut bacterial metabolism and response to intervention

Metabolism of protein by gut bacteria is potentially detrimental due to the production of toxic metabolites, such as ammonia, amines, p-cresol, and indole. The consumption of prebiotic carbohydrates results in specific changes in the composition and/or activity of the microbiota that may confer benefits to host well-being and health. Here, we have studied the impact of prebiotics on proteolysis within the gut in vitro. Anaerobic stirred batch cultures were inoculated with feces from omnivores (n = 3) and vegetarians (n = 3) and four protein sources (casein, meat, mycoprotein, and soy protein) with and without supplementation by an oligofructose-enriched inulin. Bacterial counts and concentrations of short-chain fatty acids (SCFA), ammonia, phenol, indole, and p-cresol were monitored during fermentation. Addition of the fructan prebiotic Synergy1 increased levels of bifidobacteria (P = 0.000019 and 0.000013 for omnivores and vegetarians, respectively). Branched-chain fatty acids (BCFA) were significantly lower in fermenters with vegetarians’ feces (P = 0.004), reduced further by prebiotic treatment. Ammonia production was lower with Synergy1. Bacterial adaptation to different dietary protein sources was observed through different patterns of ammonia production between vegetarians and omnivores. In volunteer samples with high baseline levels of phenol, indole, p-cresol, and skatole, Synergy1 fermentation led to a reduction of these compounds

The prebiotic effect of α-1,2 branched, low molecular weight dextran in the batch and continuous faecal fermentation system

The aim of this study was to establish the effect of smaller molecular weight (0.5 and 1.0 kDa) on prebiotic efficacy and its putative sustainability in the human gut. The prebiotic effect of α-1,2 branched, 0.5 and 1 kDa dextrans were evaluated in faecal batch fermentations as compared with inulin. Both dextrans induce similar selectivity towards Bifidobacterium sp., Lactobacillus/Enterococcus and Bacteroides/Prevotella, and producing similar concentrations of short chain fatty acids. However, the 0.5 kDa dextran was fermented faster than the 1 kDa dextran, where both produced lower amount of gas than inulin. The fermentation of 1 kDa dextran was further investigated in continuous gut models. The dextran increased Bifidobacterium and Roseburia sp. populations in the final vessel, while decreasing Clostridium histolyticum and Faecalibacterium prausnitzii. Overall, the α-1,2 branched, 1 kDa dextran induced selective effect on the gut microbiota and stimulated short chain fatty acids, indicating prebiotic sustainability in distal regions of the gut

Oligofructose alone and in combination with 2'fucosyllactose induces physiologically relevant changes in γ-aminobutyric acid and organic acid production compared to sole 2'fucosyllactose supplementation: an in vitro study

We explored the potential for the prebiotic oligofructose and prebiotic candidate 2'fucosyllactose, alone and in combination (50:50 blend) to induce physiologically relevant increases in neurotransmitter (γ-aminobutyric acid, serotonin, tryptophan, and dopamine) and organic acid (acetate, propionate, butyrate, lactate, and succinate) production as well as microbiome changes using anaerobic pH-controlled in vitro batch culture fermentations over 48 h. Changes in organic acid and neurotransmitter production were assessed by gas chromatography and liquid chromatography and, bacterial enumeration using fluorescence in situ hybridization, respectively. Both oligofructose and oligofructose/2'fucosyllactose combination fermentations induced physiologically relevant concentrations of γ-aminobutyric acid, acetate, propionate, butyrate, and succinate at completion (all P ≤ .05). A high degree of heterogeneity was seen amongst donors in both neurotransmitter and organic acid production in sole 2'FL fermentations suggesting a large responder/nonresponder status exists. Large increases in Bifidobacterium, Lactobacillus, and Bacteroides numbers were detected in oligofructose fermentation, smallest increases being detected in 2'fucosyllactose fermentation. Bacterial numbers in the combined oligofructose/2'fucosyllactose fermentation were closer to that of sole oligofructose. Our results indicate that oligofructose and oligofructose/2'fucosyllactose in combination have the potential to induce physiologically relevant increases in γ-aminobutyric and organic acid production along with offsetting the heterogenicity seen in response to sole 2'fucosyllactose supplementation

Inulin‐type fructans and short‐chain fructooligosaccharides—their role within the food industry as fat and sugar replacers and texture modifiers—what needs to be considered!

Inulin and oligofructose are classes of prebiotics belonging to a group of nondigestible carbohydrates referred to as inulin‐type fructans. While short‐chain fructooligosaccharides are enzymatically synthesized from the hydrolysis and transglycosylation of sucrose. Inulin‐type fructans and short‐chain fructooligosaccharides act as carbon sources for selective pathways supporting digestive health including altering the composition of the gut microbiota along with improving transit time. Due to their physicochemical properties, inulin‐type fructans and short‐chain fructooligosaccharides have been widely used in the food industry as partial replacements for both fat and sugar. Yet, levels of replacement need to be carefully considered as it may result in changes to physical and sensory properties that could be detected by consumers. Furthermore, it has been reported depending on the processing parameters used during production that inulin‐type fructans and short‐chain fructooligosaccharides may or may not undergo structural alterations. Therefore, this paper reviews the role of inulin‐type fructans and short‐chain fructooligosaccharides within the food industry as fat and sugar replacers and texture modifiers, their impact on final sensory properties, and to what degree processing parameters are likely to impact their functional properties