Prebiotic utilisation provides Lactiplantibacillus plantarum a competitive advantage in vitro, but is not reflected by an increased intestinal fitness.

Synbiotics combine the concepts of probiotics and prebiotics to synergistically enhance the health-associated effects of both components. Previously, we have shown that the intestinal persistence of inulin-utilizing L. plantarum Lp900 is significantly increased in rats fed an inulin-supplemented, high-calcium diet. Here we employed a competitive population dynamics approach to demonstrate that inulin and GOS can selectively enrich L. plantarum strains that utilize these substrates for growth during in vitro cultivation, but that such enrichment did not occur during intestinal transit in rats fed a GOS or inulin-supplemented diet. The intestinal persistence of all L. plantarum strains increased irrespective of their prebiotic utilization phenotype, which was dependent on the calcium level of the diet. Analysis of fecal microbiota and intestinal persistence decline rates indicated that prebiotic utilization capacity did not selectively stimulate intestinal persistence in prebiotic supplemented diets. Moreover, microbiota and organic acid profile analyses indicate that the prebiotic utilizing probiotic strains are vastly outcompeted by the endogenous prebiotic-utilizing microbiota, and that the collective enhanced persistence of all L. plantarum strains is most likely explained by their well-established tolerance to organic acids.

Exploring the Role of Inulin in Targeting the Gut Microbiota: An Innovative Strategy for Alleviating Colonic Fibrosis Induced By Irradiation.

The use of radiation therapy to treat pelvic and abdominal cancers can lead to the development of either acute or chronic radiation enteropathy. Radiation-induced chronic colonic fibrosis is a common gastrointestinal disorder resulting from the above radiation therapy. In this study, we establish the efficacy of inulin supplements in safeguarding against colonic fibrosis caused by irradiation therapy. Studies have demonstrated that inulin supplements enhance the proliferation of bacteria responsible to produce short-chain fatty acids (SCFAs) and elevate the levels of SCFAs in feces. In a mouse model of chronic radiation enteropathy, the transplantation of gut microbiota and its metabolites from feces of inulin-treated mice were found to reduce colonic fibrosis in validation experiments. Administering inulin-derived metabolites from gut microbiota led to a notable decrease in the expression of genes linked to fibrosis and collagen production in mouse embryonic fibroblast cell line NIH/3T3. In the cell line, inulin-derived metabolites also suppressed the expression of genes linked to the extracellular matrix synthesis pathway. The results indicate a novel and practical approach to safeguarding against chronic radiation-induced colonic fibrosis.

An inulin-type fructan CP-A from Codonopsis pilosula attenuates experimental colitis in mice by promoting autophagy-mediated inactivation of NLRP3 inflammasome.

Inulin-type fructan CP-A, a predominant polysaccharide in Codonopsis pilosula, demonstrates regulatory effects on immune activity and anti-inflammation. The efficacy of CP-A in treating ulcerative colitis (UC) is, however, not well-established. This study employed an in vitro lipopolysaccharide (LPS)-induced colonic epithelial cell model (NCM460) and an in vivo dextran sulfate sodium (DSS)-induced colitis mouse model to explore CP-A's protective effects against experimental colitis and its underlying mechanisms. We monitored the clinical symptoms in mice using various parameters: body weight, disease activity index (DAI), colon length, spleen weight, and histopathological scores. Additionally, molecular markers were assessed through enzyme-linked immunosorbent assay (ELISA), quantitative real-time polymerase chain reaction (qRT-PCR), immunofluorescence (IF), immunohistochemistry (IHC), and Western blotting assays. Results showed that CP-A significantly reduced reactive oxygen species (ROS), tumor necrosis factor-alpha (TNF-α), and interleukins (IL-6, IL-1ß, IL-18) in LPS-induced cells while increasing IL-4 and IL-10 levels and enhancing the expression of Claudin-1, ZO-1, and occludin proteins in NCM460 cells. Correspondingly, in vivo findings revealed that CP-A administration markedly improved DAI, reduced colon shortening, and decreased the production of myeloperoxidase (MPO), malondialdehyde (MDA), ROS, IL-1ß, IL-18, and NOD-like receptor protein 3 (NLRP3) inflammasome-associated genes/proteins in UC mice. CP-A treatment also elevated glutathione (GSH) and superoxide dismutase (SOD) levels, stimulated autophagy (LC3B, P62, Beclin-1, and ATG5), and reinforced Claudin-1 and ZO-1 expression, thereby aiding in intestinal epithelial barrier repair in colitis mice. Notably, the inhibition of autophagy via chloroquine (CQ) diminished CP-A's protective impact against colitis in vivo. These findings elucidate that CP-A's therapeutic effect on experimental colitis possibly involves mitigating intestinal inflammation through autophagy-mediated NLRP3 inflammasome inactivation. Consequently, inulin-type fructan CP-A emerges as a promising drug candidate for UC treatment.

The emergence of inflammatory microglia during gut inflammation is not affected by FFAR2 expression in intestinal epithelial cells or peripheral myeloid cells.

Gut inflammation can trigger neuroinflammation and is linked to mood disorders. Microbiota-derived short-chain fatty acids (SCFAs) can modulate microglia, yet the mechanism remains elusive. Since microglia do not express free-fatty acid receptor (FFAR)2, but intestinal epithelial cells (IEC) and peripheral myeloid cells do, we hypothesized that SCFA-mediated FFAR2 activation within the gut or peripheral myeloid cells may impact microglia inflammation. To test this hypothesis, we developed a tamoxifen-inducible conditional knockout mouse model targeting FFAR2 exclusively on IEC and induced intestinal inflammation with dextran sodium sulfate (DSS), a well-established colitis model. Given FFAR2's high expression in myeloid cells, we also investigated its role by selectively deleting it in these populations of cells. In an initial study, male and female wild-type mice received 0 or 2% DSS for 5d and microglia were isolated 3d later to assess inflammatory status. DSS induced intestinal inflammation and upregulated inflammatory gene expression in microglia, indicating inflammatory signaling via the gut-brain axis. Despite the lack of significant effects of sex in the intestinal phenotype, male mice showed higher microglial inflammatory response than females. Subsequent studies using FFAR2 knockout models revealed that FFAR2 expression in IECs or immune myeloid cells did not affect DSS-induced colonic pathology (i.e. clinical and histological scores and colon length), or colonic expression of inflammatory genes. However, FFAR2 knockout led to an upregulation of several microglial inflammatory genes in control mice and downregulation in DSS-treated mice, suggesting that FFAR2 may constrain neuroinflammatory gene expression under healthy homeostatic conditions but may permit it during intestinal inflammation. No interactions with sex were observed, suggesting sex does not play a role on FFAR2 potential function in gut-brain communication in the context of colitis. To evaluate the role of FFAR2 activated by microbiota-derived SCFAs, we employed the same knockout and DSS models adding fermentable dietary fiber (0 or 2.5% inulin for 8 wks). Despite no genotype or fiber main effects, contrary to our hypothesis, inulin feeding augmented DSS-induced inflammation and signs of colitis, suggesting context-dependent effects of fiber. These findings highlight microglial involvement in colitis-associated neuroinflammation and advance our understanding of FFAR2's role in the gut-brain axis. Although not integral, we observed that the role of FFAR2 differs between homeostatic and inflammatory conditions, underscoring the need to consider different inflammatory conditions and disease contexts when investigating the role of FFAR2 and SCFAs in the gut-brain axis.

The effect of in vitro simulated colonic pH gradients on microbial activity and metabolite production using common prebiotics as substrates.

BACKGROUND: The interplay between gut microbiota (GM) and the metabolization of dietary components leading to the production of short-chain fatty acids (SCFAs) is affected by a range of factors including colonic pH and carbohydrate source. However, there is still only limited knowledge on how the GM activity and metabolite production in the gastrointestinal tract could be influenced by pH and the pH gradient increases along the colon. RESULTS: Here we investigate the effect of pH gradients corresponding to levels typically found in the colon on GM composition and metabolite production using substrates inulin, lactose, galactooligosaccharides (GOS), and fructooligosaccharide (FOS) in an in vitro colon setup. We investigated 3 different pH regimes (low, 5.2 increasing to 6.4; medium, 5.6 increasing to 6.8 and high, 6.0 increasing to 7.2) for each fecal inoculum and found that colonic pH gradients significantly influenced in vitro simulated GM structure, but the influence of fecal donor and substrate was more pronounced. Low pH regimes strongly influenced GM with the decreased relative abundance of Bacteroides spp. and increased Bifidobacterium spp. Higher in vitro simulated colonic pH promoted the production of SCFAs in a donor- and substrate-dependent manner. The butyrate producer Butyricimonas was enriched at higher pH conditions, where also butyrate production was increased for inulin. The relative abundance of Phascolarctobacterium, Bacteroides, and Rikenellaceae also increased at higher colonic pH, which was accompanied by increased production of propionate with GOS and FOS as substrates. CONCLUSIONS: Together, our results show that colonic substrates such as dietary fibres influence GM composition and metabolite production, not only by being selectively utilized by specific microbes, but also because of their SCFA production, which in turn also influences colonic pH and overall GM composition and activity. Our work provides details about the effect of the gradients of rising pH from the proximal to distal colon on fermenting dietary substrates in vitro and highlights the importance of considering pH in GM research.

Effects of Oat ß-Glucan and Inulin on Alleviation of Nonalcoholic Steatohepatitis Aggravated by Circadian Disruption in C57BL/6J Mice.

This was the first study that examined the effects of oat ß-glucan and inulin on diet-induced nonalcoholic steatohepatitis (NASH) in circadian-disrupted (CD)-male C57BL/6J mice. CD intensified NASH, significantly increasing alanine aminotransferase and upregulating hepatic tumor necrosis factor α (TNFα) and transforming growth factor ß 1 (TGFß1). However, these observations were significantly alleviated by oat ß-glucan and inulin treatments. Compared to CD NASH mice, oat ß-glucan significantly decreased the liver index, aspartate aminotransferase (AST), and insulin. In prebiotic-treated and CD NASH mice, significant negative correlations were found between enrichment of Muribaculaceae bacterium Isolate-036 (Harlan), Muribaculaceae bacterium Isolate-001 (NCI), and Bacteroides ovatus after oat ß-glucan supplementation with TNFα and TGFß1 levels; and enrichment of Muribaculaceae bacterium Isolate-110 (HZI) after inulin supplementation with AST level. In conclusion, oat ß-glucan and inulin exhibited similar antiliver injury, anti-inflammatory, and antifibrotic activities but had no effect on cecal short-chain fatty acids and gut microbiota diversity in CD NASH mice.

Innovative application of a novel di-D-fructofuranose 1,2':2,3'-dianhydride hydrolase (DFA-IIIase) from Duffyella gerundensis A4 to burdock root to improve nutrition.

Burdock is native to Europe and Asia and rich in many functional ingredients, including biomacromolecule polysaccharide inulin. The prebiotic fructan inulin can provide energy to organisms via several pathways. One pathway is that inulin fructotransferase (IFTase) first converts inulin to III-type difructose anhydride (DFA-III), which has many beneficial physiological functions. Then, DFA-III is hydrolyzed to inulobiose, which is a Fn-type prebiotic fructo-oligosaccharide, via difructose anhydride hydrolase (DFA-IIIase). However, there has been no study on the application of IFTase or DFA-IIIase to process burdock to increase DFA-III or inulobiose. Moreover, only five DFA-IIIases have been reported to date and all of them are from the Arthrobacter genus. Whether other microbes except for the Arthrobacter genus can utilize DFA-III through DFA-IIIase is unknown. In this work, a DFA-IIIase from Duffyella gerundensis A4 (D. gerundensis A4), abbreviated as DgDFA-IIIase, was identified and characterized in detail. DgDFA-IIIase is a bifunctional enzyme, that is, besides its hydrolytic ability to DFA-III, it has the same catalytic ability as IFTase to inulin. The enzyme was applied to the burdock root aiming at inulin and DFA-III, and inulobiose was produced with an increase in Gn-type fructo-oligosaccharide. The work verifies that microorganisms of the non-Arthrobacter genus also have the potential ability to use DFA-III by DFA-IIIase, and DFA-IIIase is feasible to increase functional substances of burdock root instead of IFTase and endo-inulinase, which paves the way for the production of functional food utilizing the polysaccharide inulin to improve nutrition and health.

The Complex GH32 Enzyme Orchestra from Priestia megaterium Holds the Key to Better Discriminate Sucrose-6-phosphate Hydrolases from Other ß-Fructofuranosidases in Bacteria.

Inulin is widely used as a prebiotic and emerging as a priming compound to counteract plant diseases. We isolated inulin-degrading strains from the lettuce phyllosphere, identified as Bacillus subtilis and Priestia megaterium, species hosting well-known biocontrol organisms. To better understand their varying inulin degradation strategies, three intracellular ß-fructofuranosidases from P. megaterium NBRC15308 were characterized after expression in Escherichia coli: a predicted sucrose-6-phosphate (Suc6P) hydrolase (SacAP1, supported by molecular docking), an exofructanase (SacAP2), and an invertase (SacAP3). Based on protein multiple sequence and structure alignments of bacterial glycoside hydrolase family 32 enzymes, we identified conserved residues predicted to be involved in binding phosphorylated (Suc6P hydrolases) or nonphosphorylated substrates (invertases and fructanases). Suc6P hydrolases feature positively charged residues near the structural catalytic pocket (histidine, arginine, or lysine), whereas other ß-fructofuranosidases contain tryptophans. This correlates with our phylogenetic tree, grouping all predicted Suc6P hydrolases in a clan associated with genomic regions coding for transporters involved in substrate phosphorylation. These results will help to discriminate between Suc6P hydrolases and other ß-fructofuranosidases in future studies and to better understand the interaction of B. subtilis and P. megaterium endophytes with sucrose and/or fructans, sugars naturally present in plants or exogenously applied in the context of defense priming.

The agavins (Agave carbohydrates) story.

Fructans, are carbohydrates defined as fructose-based polymers with countable degree of polymerization (DP) ranging so far from DP3 to DP60. There are different types of fructans depending on their molecular arrangement. They are categorized as linear inulins and levans, neoseries of inulin and levan, branched graminans, and highly branched neofructans, so called agavins (Agave carbohydrates). It is worth to note that agavins are the most recently described type of fructans and they are also the most complex ones. The complexity of these carbohydrates is correlated to their various isomers and degree of polymerization range, which is correlated to their multifunctional application in industry and human health. Here, we narrate the story of the agavins' discovery. This included their chemical characterization, their benefits, biotechnological applications, and drawbacks over human health. Finally, a perspective of the study of agavins and their interactions with other metabolites through metabolomics is proposed.

Inulin Can Improve Red Blood Cell Cryopreservation by Promoting Vitrification, Stabilizing Cell Membranes, and Inhibiting Ice Recrystallization.

In transfusion medicine, the cryopreservation of red blood cells (RBCs) is of major importance. The organic solvent glycerol (Gly) is considered the current gold-standard cryoprotectant (CPA) for RBC cryopreservation, but the deglycerolization procedure is complex and time-consuming, resulting in severe hemolysis. Therefore, it remains a research hotspot to find biocompatible and effective novel CPAs. Herein, the natural and biocompatible inulin, a polysaccharide, was first employed as a CPA for RBC cryopreservation. The presence of inulin could improve the thawed RBC recovery from 11.83 ± 1.40 to 81.86 ± 0.37%. It was found that inulin could promote vitrification because of its relatively high viscosity and glass transition temperature (Tg'), thus reducing the damage during cryopreservation. Inulin possessed membrane stability, which also had beneficial effects on RBC recovery. Moreover, inulin could inhibit the mechanical damage induced by ice recrystallization during thawing. After cryopreservation, the RBC properties were maintained normally. Mathematical modeling analysis was adopted to compare the performance of inulin, Gly, and hydroxyethyl starch (HES) in cryopreservation, and inulin presented the best efficiency. This work provides a promising CPA for RBC cryopreservation and may be beneficial for transfusion therapy in the clinic.

Insights in inulin binding and inulin oligosaccharide formation by novel multi domain endo-inulinases from Botrytis cinerea.

World-wide, pathogenic fungi such as Botrytis cinerea cause tremendous yield losses in terms of food production and post-harvest food decay. Many fungi produce inulin-type oligosaccharides (IOSs) from inulin through endo-inulinases which typically show a two domain structure. B.cinerea lacks a two domain endo-inulinase but contains a three domain structure instead. Genome mining revealed three and four domain (d4) enzymes in the fungal kingdom. Here, three and two domain enzymes were compared in their capacity to produce IOSs from inulin. Hill kinetics were observed in three domain enzymes as compared to Michaelis-Menten kinetics in two domain enzymes, suggesting that the N-terminal extension functions as a carbohydrate binding module. Analysis of the IOS product profiles generated from purified GF6, GF12, GF16 and GF18 inulins and extensive sugar docking approaches led to enhanced insights in the active site functioning, revealing subtle differences between the endo-inulinases from Aspergillus niger and B. cinerea. Improved insights in structure-function relationships in fungal endo-inulinases offer opportunities to develop superior enzymes for the production of specific IOS formulations to improve plant and animal health (priming agents, prebiotics).

Dynamic response of different types of gut microbiota to fructooligosaccharides and inulin.

Fructooligosaccharides (FOS) and inulin are beneficial for human health. However, their benefits differ in individuals who consume prebiotics. Several factors contribute to this variation, including host genetics and differences in the gut microbiota. Bifidobacterium and Bacteroides are strong carbohydrate-utilizing bacteria in the gut, and the level of the Bacteroides/Bifidobacterium (Ba/Bi) ratio in the gut is closely related to the body's ability to utilize prebiotics. However, how to select the type of prebiotics more beneficial for populations with specific Ba/Bi backgrounds and the underlying regulatory mechanisms remain unclear. Here, we explored the dynamics of the gut microbiota and metabolic functions during the in vitro fermentation of FOS and inulin in two different groups: Bacteroides/Bifidobacterium high (H) and Bacteroides/Bifidobacterium low (L). This study revealed that the baseline Ba/Bi ratio had a greater impact on the gut microbiota compared to prebiotic species. Noticeable differences were observed between the two groups after prebiotic intervention, with the H group being more likely to benefit from the prebiotic intervention. Compared to the L group, the H group exhibited significantly higher microbial α-diversity; the co-abundance response group 1 (CARG1) members Ruminococcus gnavus and Blautia involved in the synthesis of propionic and butyric acids increased significantly, the abundance of pathogenic bacteria such as Escherichia Shigella decreased significantly, and the ability to degrade carbohydrates and synthesize fatty acids was greater. Regression modeling showed that the key microbiota could predict the short-chain fatty acid (SCFA) levels, with FOS associated with the ecological roles of CARG2 and CARG7 and inulin associated with CARG4, which provides the basis for the use of prebiotics in nutritional applications and the stratification of populations based on pertinent microbiota profiles to explain the incongruent health effects in human intervention studies.

Maternal inulin alleviates high-fat diet-induced lipid disorder in offspring by epigenetically modulating hypothalamus feeding circuit-related genes.

Increasing evidence supports the existence of fetal-originated adult diseases. Recent research indicates that the intrauterine environment affects the fetal hypothalamic energy intake center. Inulin is a probiotic that can moderate metabolic disorders, but whether maternal inulin intervention confers long-term metabolic benefits to lipid metabolism in offspring in their adult lives and the mechanism involved are unknown. Here, we used a maternal overnutrition model that was induced by excess energy intake before and during pregnancy and lactation and maternal inulin intervention was performed during pregnancy and lactation. The hypothalamic genome methylation in offspring was analyzed using a methylation array. The results showed that maternal inulin treatment modified the maternal high-fat diet (HFD)-induced increases in body weight, adipose tissue weight, and serum insulin and leptin levels and decreases in serum adiponectin levels. Maternal inulin intervention regulated the impairments in hypothalamic leptin resistance, induced the methylation of Socs3, Npy, and Il6, and inhibited the methylation of Lepr in the hypothalamus of offspring. In conclusion, maternal inulin intervention modifies offspring lipid metabolism, and the underlying mechanism involves the methylation of genes in the hypothalamus feeding circuit.

Production of polyhydroxybutyrate by coupled saccharification-fermentation of inulin.

Inulin is a fructose-based polysaccharide that can be found in several plant species, from grass and onions to chicory roots; thus, it has the potential to be an excellent renewable source of fructose for several industrial applications. Among them, inulin hydrolysis can be coupled to a fermentation operation to produce polyhydroxybutyrate (PHB) using Cupriavidus necator H16. This work reports the PHB production process involving chicory root inulin hydrolysis using inulinase Novozym 960 followed by a C. necator fermentation. It was found that the maximum saccharification (95% wt.) was reached at 269 U/ginulin after 90 min. The hydrolysates obtained were then inoculated with C. necator, leading to a biomass concentration of 4 g/L with 30% (w/w) polymer accumulation. Although PHB production was low, during the first hours, the cell growth and polymer accumulation detected did not coincide with a fructose concentration decrease, suggesting a simultaneous saccharification and fermentation process, potentially alleviating the product inhibition inherent to the inulinase-fructose system. The characterization of the obtained PHB showed a polymer with more homogeneous values of Mw, and better thermal stability than PHB produced using pure fructose as a fermentation substrate. The results obtained demonstrate a viable alternative carbon substrate for PHB production, opening the possibility for inulin-rich renewable feedstock valorization.

Inulin-like polysaccharide ABWW may impede CCl4 induced hepatic stellate cell activation through mediating the FAK/PI3K/AKT signaling pathway in vitro & in vivo.

Studies have shown that terrestrial acidic polysaccharides containing carboxyl groups and seaweed sulfated polysaccharides have strong potential in anti-liver fibrosis. However, there is no investigation on the anti-liver fibrosis of fructan, a ubiquitous natural polysaccharide. The present study aimed to understand the effect of fructan in ameliorating carbon tetrachloride (CCl4)-induced liver fibrosis in mice. Here, an inulin-like fructan ABWW from Achyranthes bidentata Bl. was characterized by fructose enzymatic hydrolysis, methylation analysis, ESI-MS, and NMR. It was composed of →2)-ß-d-Fruf-(1→ and →2)-ß-d-Fruf-(1, 6→, terminated with →1)-α-d-Glcp and →2)-ß-d-Fruf residues. The biological studies showed that ABWW could improve liver damage and liver fibrosis induced by CCl4in vivo and inhibit hepatic stellate cell (HSC) activation and migration in vitro. We further demonstrated that ABWW inhibited LX2 activation via suppressing the FAK/PI3K/AKT signaling pathway. Hence, ABWW might be a potential novel active compound for anti-fibrosis new drug development.

Simple procedure to enhance pulsed amperometric detector (PAD) response stability for inulin-type fructans analysis. Application to a case study with chicory taproot.

A new electrode management, within the HPAEC-PAD systems, was proposed to measure inulin-type fructans in chicory roots, grown under two lighting periods: 12 h (T-12 h) and 24 h continuous lighting (T-24 h-CL), with the same daily light integral (DLI). The amperometric cell turn-off (PAD-Off) after elution of carbohydrate of interest, allowed the stabilization of the PAD response, avoiding excessive electrode surface oxidation. The enhanced signal stability allowed the application of fucose as internal standard (ISTD) for data normalization, improving the correctness of linear calibration curves and the quantification of fructans in the case study of chicory plants. T-24 h-CL decreased FW and DW of chicory leaves while increasing these parameters in roots. Fructans amount in chicory roots was significantly higher in the T-24-CL photoperiod. The accuracy of prebiotics quantification by PAD-Off emphasized significant differences between light treatments. CL can improve the yield and quality of chicory roots.

Identification of inulin-responsive bacteria in the gut microbiota via multi-modal activity-based sorting.

Prebiotics are defined as non-digestible dietary components that promote the growth of beneficial gut microorganisms. In many cases, however, this capability is not systematically evaluated. Here, we develop a methodology for determining prebiotic-responsive bacteria using the popular dietary supplement inulin. We first identify microbes with a capacity to bind inulin using mesoporous silica nanoparticles functionalized with inulin. 16S rRNA gene amplicon sequencing of sorted cells revealed that the ability to bind inulin was widespread in the microbiota. We further evaluate which taxa are metabolically stimulated by inulin and find that diverse taxa from the phyla Firmicutes and Actinobacteria respond to inulin, and several isolates of these taxa can degrade inulin. Incubation with another prebiotic, xylooligosaccharides (XOS), in contrast, shows a more robust bifidogenic effect. Interestingly, the Coriobacteriia Eggerthella lenta and Gordonibacter urolithinfaciens are indirectly stimulated by the inulin degradation process, expanding our knowledge of inulin-responsive bacteria.

Dietary Galactooligosaccharides Supplementation as a Gut Microbiota-Regulating Approach to Lower Early Life Arsenic Exposure.

Prebiotics may stimulate beneficial gut microorganisms. However, it remains unclear whether they can lower the oral bioavailability of early life arsenic (As) exposure via regulating gut microbiota and altering As biotransformation along the gastrointestinal (GI) tract. In this study, weanling mice were exposed to arsenate (iAsV) via diet (7.5 µg As g-1) amended with fructooligosaccharides (FOS), galactooligosaccharides (GOS), and inulin individually at 1% and 5% (w/w). Compared to As exposure control mice, As concentrations in mouse blood, liver, and kidneys and As urinary excretion factor (UEF) were reduced by 43.7%-74.1% when treated with 5% GOS. The decrease corresponded to a significant proliferation of Akkermansia and Psychrobacter, reduced percentage of inorganic arsenite (iAsIII) and iAsV by 47.4% and 65.4%, and increased proportion of DMAV in intestinal contents by 101% in the guts of mice treated with 5% GOS compared to the As control group. In contrast, FOS and inulin either at l% or 5% did not reduce As concentration in mouse blood, liver, and kidneys or As UEF. These results suggest that GOS supplementation may be a gut microbiota-regulating approach to lower early life As exposure via stimulating the growth of Akkermansia and Psychrobacter and enhancing As methylation in the GI tract.

Inulin Supplementation Modulates the Hepatic Transcriptome, Metabolome, and Ferritin Content in Ovariectomized Rats.

SCOPE: Liver is an important metabolic organ regulating whole-body homeostasis. This study aims to investigate how prebiotic-induced changes in the metabolic activity of the gut microbiome (GM) and dietary calcium depletion modulates the hepatic metabolome and transcriptome. METHODS AND RESULTS: The serum metabolome, liver metabolome, and transcriptome are determined on samples from ovariectomized (OVX) rats fed a control diet (Control, n = 7), a control diet supplemented with 5% w/w inulin (Inulin, n = 7), or a calcium-deficient diet (CaDef, n = 7). Inulin fortification is associated with higher serum concentrations of acetate, 3-hydroxybutyrate, and reduced concentration of dimethyl sulfone, revealing that changes in the metabolic activity of the GM are reflected in circulating metabolites. Metabolomics also reveal that the inulin-fortified diet results in lower concentrations of hepatic glutamate, serine, and hypoxanthine while transcriptomics reveal accompanying effects on the hepatic expression of ferric iron binding-related genes. Inulin fortification also induces effects on the hepatic expression of genes involved in olfactory transduction, suggesting that prebiotics regulate liver function through yet unidentified mechanisms involving olfactory receptors. CONCLUSION: Inulin ingestion impacts hepatic gene expression and is associated with an upregulation of ferritin synthesis-related genes and liver ferritin content.

Properties of the extracellular alkaline inulinase produced by haloalkaliphilic phototrophic bacteria Ectothiorodospirea mobilis.

The studies have revealed alkaline exoinulinase produced by haloalkaliphilic phototrophic bacteria Ectothiorhodospirea mobilis Al-2 for the first time. A new method for the isolation of a homogeneous exoinulinase from the culture broth was developed and the properties of this enzyme have been investigated. It was shown that specified exoinulinase in contrast to the studied exoinulinases produced by microorganisms exhibits catalytic activity at the wide range of pH (7.0-10) and a temperature (20-60 °C) with a maximum of the inulolitic activity at pH 9.0 and 50 °C. The studied exoinulinase possessing also invertase activity (I/S1.4) is a monomeric protein with molecular mass 57Kda, as well as Km and Vmax for inulin 3.8 mM/ml and 10 µmol/ml/min-1, respectively. The studies of the influence of different metal ions on enzyme activity have shown that Mn+2, Cu+2, Co+2, Mg+2, NaCl 5-7% promote relatively higher catalytic activity while Zn+2, Cu+2 and Fe+2 partially suppress the enzyme activity and Hg2+completely inactivates the enzyme.The formation of only fructose and glucose at the enzymatic hydrolysis of inulin confirms that the studied exoinulinase belongs to the exo-type of enzymes. The obtained results supplement our fundamental knowledge in biochemistry-enzymology, as well as the biodiversity of microorganisms expressing exoinulinase. The studied exoinulinase exhibits activity at salinity of the medium and can potentially be used in the biotechnology of inulin bioconversion into bioproducts under alkaline conditions.