An exploratory study on the influence of orange juice on gut microbiota using a dynamic colonic model

The Effect of Opuntia ficus Mucilage Pectin and Citrus aurantium Extract Added to a Food Matrix on the Gut Microbiota of Lean Humans and Humans with Obesity

Experimental studies have provided evidence that physicochemical interactions in the food matrix can modify the biologically beneficial effects of bioactive compounds, including their effect on gut microbiota. This work aimed to evaluate the effect of a food gel matrix with Opuntia ficus cladodes mucilage pectin and Citrus Aurantium extract on the growth of four beneficial gut bacteria obtained from the fecal microbiota of people who are lean or who have obesity after digestion in the upper digestive system. To accomplish this, a base formulation of Opuntia ficus cladodes mucilage with or without C. aurantium extract was submitted to an ex vivo fecal fermentation in an automatic and robotic intestinal system. The changes in the intestinal microbiota were determined by means of plate culture and 16S sequencing, while short-chain fatty acids (SCFA) produced in the colon were determined via gas chromatography. In the presence of the extract in formulation, greater growth of Bifidobacterium spp. (+1.6 Log10 Colonic Forming Unit, UFC) and Lactobacillus spp. (+2 Log10 UFC) in the microbiota of lean people was observed. Only the growth in Salmonella spp. (-1 Log10 UFC) from both microbiota was affected in the presence of the extract, which decreased in the ascending colon. SCFA was mainly produced by the microbiota of people who were lean rather than those who had obesity in the presence of the extract, particularly in the ascending colon. The effect of sour orange extract seems to depend on the origin of the microbiota, whether in people who have obesity (25 mM/L) or are lean (39 mM/L).

The Effect of Delivery Matrix on Bifidobacterium animalis subsp. lactis HN019 Survival through In Vitro Human Digestion

Bifidobacterium animalis subsp. lactis HN019 is a probiotic with several documented human health benefits. Interest in probiotics has led to the development of new formats that probiotics, including HN019, can be supplemented into. In this study, we looked at common HN019 formats such as frozen culture and freeze-dried powder as well as supplementing it into the following food matrices: yogurts (dairy, soy, and oat based), xanthan gum-based tablets, pulpless orange juice, whey sports drink, and dark chocolate (70% cocoa). In this work, our aim was to investigate whether the food matrix that carried HN019 via simulated human digestion (a dual model system mimicking both upper and lower gastrointestinal digestion) influenced probiotic delivery. To that end, we validated and used a real-time qPCR assay to detect HN019 after simulated digestion. In addition, we also measured the effect on a panel of metabolites. After simulated digestion, we were able to detect HN019 from all the matrices tested, and the observed changes to the metabolite profile were consistent with those expected from the food matrix used. In conclusion, this work suggests that the food matrix supplemented with HN019 did not interfere with delivery to the colon via simulated human digestion.

Zein as an Effective Carrier for Hesperidin Delivery Systems with Improved Prebiotic Potential

Hesperidin is a polyphenol derived from citrus fruits that has a broad potential for biological activity and the ability to positively modify the intestinal microbiome. However, its activity is limited by its low solubility and, thus, its bioavailability-this research aimed to develop a zein-based hesperidin system with increased solubility and a sustained release profile. The study used triple systems enriched with solubilizers to maximize solubility. The best system was the triple system hesperidin-zein-Hpβ-CD, for which the solubility improved by more than six times. A significant improvement in the antioxidant activity and the ability to inhibit α-glucosidase was also demonstrated, due to an improved solubility. A release profile analysis was performed in the subsequent part of the experiments, confirming the sustained release profile of hesperidin, while improving the solubility. Moreover, the ability of selected probiotic bacteria to metabolize hesperidin and the effect of this flavonoid compound on their growth were investigated.

Adding a polyphenol-rich fiber bundle to food impacts the gastrointestinal microbiome and metabolome in dogs

Introduction

Pet foods fortified with fermentable fibers are often indicated for dogs with gastrointestinal conditions to improve gut health through the production of beneficial post-biotics by the pet's microbiome.

Methods

To evaluate the therapeutic underpinnings of pre-biotic fiber enrichment, we compared the fecal microbiome, the fecal metabolome, and the serum metabolome of 39 adult dogs with well-managed chronic gastroenteritis/enteritis (CGE) and healthy matched controls. The foods tested included a test food (TF1) containing a novel pre-biotic fiber bundle, a control food (CF) lacking the fiber bundle, and a commercially available therapeutic food (TF2) indicated for managing fiber-responsive conditions. In this crossover study, all dogs consumed CF for a 4-week wash-in period, were randomized to either TF1 or TF2 and fed for 4 weeks, were fed CF for a 4-week washout period, and then received the other test food for 4 weeks.

Results

Meaningful differences were not observed between the healthy and CGE dogs in response to the pre-biotic fiber bundle relative to CF. Both TF1 and TF2 improved stool scores compared to CF. TF1-fed dogs showed reduced body weight and fecal ash content compared to either CF or TF2, while stools of TF2-fed dogs showed higher pH and lower moisture content vs. TF1. TF1 consumption also resulted in unique fecal and systemic metabolic signatures compared to CF and TF2. TF1-fed dogs showed suppressed signals of fecal bacterial putrefactive metabolism compared to either CF or TF2 and increased saccharolytic signatures compared to TF2. A functional analysis of fecal tryptophan metabolism indicated reductions in fecal kynurenine and indole pathway metabolites with TF1. Among the three foods, TF1 uniquely increased fecal polyphenols and the resulting post-biotics. Compared to CF, consumption of TF1 largely reduced fecal levels of endocannabinoid-like metabolites and sphingolipids while increasing both fecal and circulating polyunsaturated fatty acid profiles, suggesting that TF1 may have modulated gastrointestinal inflammation and motility. Stools of TF1-fed dogs showed reductions in phospholipid profiles, suggesting fiber-dependent changes to colonic mucosal structure.

Discussion

These findings indicate that the use of a specific pre-biotic fiber bundle may be beneficial in healthy dogs and in dogs with CGE.

Evaluation of Different Advanced Approaches to Simulation of Dynamic In Vitro Digestion of Polyphenols from Different Food Matrices-A Systematic Review

Phenolic compounds have become interesting bioactive antioxidant compounds with implications for obesity, cancer and inflammatory gastrointestinal pathologies. As the influence of digestion and gut microbiota on antioxidant behavior is yet to be completely elucidated, and due to limitations associated to in vivo studies, dynamic in vitro gastrointestinal models have been promoted. A systematic review was conducted of different databases (PubMed, Web of Science and Scopus) following PRISMA guidelines to assess different dynamic digestion models and assay protocols used for phenolic compound research regarding bioaccesibility and interaction with colonic microbiota. Of 284 records identified, those including dynamic multicompartmental digestion models for the study of phenolic compound bioaccesibility, bioactivity and the effects of microbiota were included, with 57 studies meeting the inclusion criteria. Different conditions and experimental configurations as well as administered doses, sample treatments and microbiological assays of dynamic digestion studies on polyphenols were recorded and compared to establish their relevance for the dynamic in vitro digestion of phenolic compounds. While similarities were observed in certain experimental areas, a high variability was found in others, such as administered doses. A description of considerations on the study of the digestion of phenolic compounds is proposed to enhance comparability in research.

Functional Fermented Milk with Fruit Pulp Modulates the In Vitro Intestinal Microbiota

The effect of putative probiotic fermented milk (FM) with buriti pulp (FMB) or passion fruit pulp (FMPF) or without fruit pulp (FMC) on the microbiota of healthy humans was evaluated. FM formulations were administered into a simulator of the human intestinal microbial ecosystem (SHIME^®) to evaluate the viability of lactic acid bacteria (LAB), microbiota composition, presence of short-chain fatty acids (SCFA), and ammonium ions. The probiotic LAB viability in FM was affected by the addition of the fruit pulp. Phocaeicola was dominant in the FMPF and FMB samples; Bifidobacterium was related to FM formulations, while Alistipes was associated with FMPF and FMB, and Lactobacillus and Lacticaseibacillus were predominant in FMC. Trabulsiella was the central element in the FMC, while Mediterraneibacter was the central one in the FMPF and FMB networks. The FM formulations increased the acetic acid, and a remarkably high amount of propionic and butyric acids were detected in the FMB treatment. All FM formulations decreased the ammonium ions compared to the control; FMPF samples stood out for having lower amounts of ammonia. The probiotic FM with fruit pulp boosted the beneficial effects on the intestinal microbiota of healthy humans in addition to increasing SCFA in SHIME^® and decreasing ammonium ions, which could be related to the presence of bioactive compounds.

The Impact of Plant Phytochemicals on the Gut Microbiota of Humans for a Balanced Life

The gastrointestinal tract of humans is a complex microbial ecosystem known as gut microbiota. The microbiota is involved in several critical physiological processes such as digestion, absorption, and related physiological functions and plays a crucial role in determining the host’s health. The habitual consumption of specific dietary components can impact beyond their nutritional benefits, altering gut microbiota diversity and function and could manipulate health. Phytochemicals are non-nutrient biologically active plant components that can modify the composition of gut microflora through selective stimulation of proliferation or inhibition of certain microbial communities in the intestine. Plants secrete these components, and they accumulate in the cell wall and cell sap compartments (body) for their development and survival. These compounds have low bioavailability and long time-retention in the intestine due to their poor absorption, resulting in beneficial impacts on gut microbiota population. Feeding diets containing phytochemicals to humans and animals may offer a path to improve the gut microbiome resulting in improved performance and/or health and wellbeing. This review discusses the effects of phytochemicals on the modulation of the gut microbiota environment and the resultant benefits to humans; however, the effect of phytochemicals on the gut microbiota of animals is also covered, in brief.

Spirulina platensis biomass enhances the proliferation rate of Lactobacillus acidophilus 5 (La-5) and combined with La-5 impact the gut microbiota of medium-age healthy individuals through an in vitro gut microbiome model

This study first evaluated the stimulatory effect of S. platensis biomass on the growth of L. acidophilus and the metabolic activity during fermentation (37 °C, 72 h) in a culture medium. The results demonstrated a higher impact of S. platensis biomass than fructooligosaccharide (FOS), an established prebiotic. Higher L. acidophilus proliferation rates and metabolic activity were observed (lower pH values and higher concentrations of acetic, lactic, and propionic acids) in the presence of S. platensis. Then, we evaluated the effects of the S. platensis biomass (1.5 g, twice a day, 5 days) in association with L. acidophilus (10⁶ CFU/g) on the gut microbiota composition of medium-age healthy individuals through the Simulator of Human Intestinal Microbial Ecosystem (SHIME®) and measurement of metabolites. L. acidophilus (La5) and L. acidophilus + S. platensis (Spi-La5) could positively modulate the intestinal microbiota. The administration of La5 resulted in increases in Bacteroides, Megasphaera, Lactobacillus, and Parabacteroides genus abundance, with a consequent decrease in ammonium ions. The administration of Spi-La5 increased the abundance of the genus Erysipelatoclostridium, Roseburia, Enterococcus, Bifidobacterium, Coriobacteriaceae UCG-003, Enterobacter, and Paraclostridium. The results demonstrate that the intestinal microbiota was differently modified by administrating La5 and Spi-La5 and indicate the latter as an alternative for microbiota positive modulation in healthy individuals.

Improvement of Antioxidant Properties in Fruit from Two Blood and Blond Orange Cultivars by Postharvest Storage at Low Temperature

Numerous studies have revealed the remarkable health-promoting activities of citrus fruits, all of them related to the accumulation of bioactive compounds, including vitamins and phytonutrients. Anthocyanins are characteristic flavonoids present in blood orange, which require low-temperature for their production. Storage at low-temperature of blood oranges has been proven to be a feasible postharvest strategy to increase anthocyanins in those countries with warm climates. To our knowledge, no studies comparing the effect of postharvest storage effect on phenylpropanoid accumulation in cultivars with and without anthocyanins production have been published. We have investigated the effect of postharvest cold storage in flavonoid accumulation in juice from Citrus sinensis L. Osbeck in two different oranges: Pera, a blond cultivar, and Moro, a blood one. Our findings indicate a different response to low-temperature of fruit from both cultivars at biochemical and molecular levels. Little changes were observed in Pera before and after storage, while a higher production of phenylpropanoids (3.3-fold higher) and flavonoids (1.4-fold higher), including a rise in anthocyanins from 1.3 ± 0.7 mg/L to 60.0 ± 9.4 mg/L was observed in Moro concurrent with an upregulation of the biosynthetic genes across the biosynthetic pathway. We show that postharvest storage enhances not only anthocyanins but also other flavonoids accumulation in blood oranges (but not in blond ones), further stimulating the interest in blood orange types in antioxidant-rich diets.

Feeding Fiber-Bound Polyphenol Ingredients at Different Levels Modulates Colonic Postbiotics to Improve Gut Health in Dogs

Simple Summary

Microbes present in the large intestine of humans and companion animals produce bioactive metabolites from host-ingested food. These bioactive metabolites can influence host health. A prior study in dogs that were healthy or had chronic enteritis/gastroenteritis showed that stool quality improved when they ate food containing a fiber bundle made from fibers of pecan shells, flax seed, cranberry, citrus, and beet. In addition, eating food containing the fiber bundle resulted in the gut bacteria shifting from digesting mainly protein to digesting mainly carbohydrates. The present study tested the impact of the fiber bundle at a lower range of concentrations in dogs. Fecal levels of several bioactive metabolites with beneficial antioxidant or anti-inflammatory properties increased after dogs consumed food with the fiber bundle, though no changes in the bacteria or their functional pathways were observed. Stool quality remained in the acceptable range. These results suggest that the gut bacteria were able to digest the fiber bundle to produce beneficial bioactive metabolites to improve host health.

Abstract

This study assessed changes in canine fecal metabolites and microbiota with the consumption of foods with increasing concentrations of a fiber bundle including pecan shells, flax seed, and powders of cranberry, citrus, and beet that was previously shown (at 14% w/w) to improve stool quality, shift fecal bacterial metabolism from proteolysis to saccharolysis, increase abundance of saccharolytic bacteria, and decrease abundance of proteolytic bacteria. In this study, 48 healthy adult dogs were split evenly to consume different inclusion levels (0%, 1%, 2%, and 4%) of the fiber bundle for a 31-day period following a 28-day pre-feed period. Increases from baseline in the fecal short-chain fatty acids butyric acid, valeric acid, and hexanoic acid were observed only in the dogs that consumed the food with the 4% fiber bundle. With addition of any level of the fiber bundle, increases were seen in the polyphenols hesperidin, hesperetin, ponciretin, secoisolariciresinol diglucoside, secoisolariciresinol, and enterodiol. However, fecal microbiota and their metabolism, and stool scores were largely unaffected by the fiber bundle. Overall, addition of the fiber bundle appeared to increase bioactive metabolites of increased antioxidant and anti-inflammatory potency for beneficial to health and, at levels ≥4%, shifted gut bacterial metabolism toward saccharolysis.

Phenolic Compounds Promote Diversity of Gut Microbiota and Maintain Colonic Health

The role of non-energy-yielding nutrients on health has been meticulously studied, and the evidence shows that a compound can exert significant effects on health even if not strictly required by the organism. Phenolic compounds are among the most widely studied molecules that fit this description; they are found in plants as secondary metabolites and are not required by humans for growth or development, but they can influence a wide array of processes that modulate health across multiple organs and systems. The lower gastrointestinal tract is a prime site of action of phenolic compounds, namely, by their effects on gut microbiota and colonic health. As with humans, phenolic compounds are not required by most bacteria but can be substrates of others; in fact, some phenolic compounds exert antibacterial actions. A diet rich in phenolic compounds can lead to qualitative and quantitative effects on gut microbiota, thereby inducing indirect health effects in mammals through the action of these microorganisms. Moreover, phenolic compounds may be fermented by the gut microbiota, thereby modulating the compounds bioactivity. In the colon, phenolic compounds promote anti-inflammatory, anti-oxidant and antiproliferative actions. The aim of the present review is to highlight the role of phenolic compounds on maintaining or restoring a healthy microbiota and overall colonic health. Mechanisms of action that substantiate the reported evidence will also be discussed.

Diet and the Microbiota-Gut-Brain Axis: Sowing the Seeds of Good Mental Health

Over the past decade, the gut microbiota has emerged as a key component in regulating brain processes and behavior. Diet is one of the major factors involved in shaping the gut microbiota composition across the lifespan. However, whether and how diet can affect the brain via its effects on the microbiota is only now beginning to receive attention. Several mechanisms for gut-to-brain communication have been identified, including microbial metabolites, immune, neuronal, and metabolic pathways, some of which could be prone to dietary modulation. Animal studies investigating the potential of nutritional interventions on the microbiota-gut-brain axis have led to advancements in our understanding of the role of diet in this bidirectional communication. In this review, we summarize the current state of the literature triangulating diet, microbiota, and host behavior/brain processes and discuss potential underlying mechanisms. Additionally, determinants of the responsiveness to a dietary intervention and evidence for the microbiota as an underlying modulator of the effect of diet on brain health are outlined. In particular, we emphasize the understudied use of whole-dietary approaches in this endeavor and the need for greater evidence from clinical populations. While promising results are reported, additional data, specifically from clinical cohorts, are required to provide evidence-based recommendations for the development of microbiota-targeted, whole-dietary strategies to improve brain and mental health.

Probiotic-fermented blueberry juice prevents obesity and hyperglycemia in high fat diet-fed mice in association with modulating the gut microbiota

Blueberry dietary interventions have demonstrated remarkable potential against obesity and type 2 diabetes mellitus. However, the effects of fermented blueberry juice on metabolic syndrome, the gut microbiota, and insulin resistance have not yet been reported. This study aimed to investigate the potential of fermented blueberry juice against obesity, hyperglycemia, and gut microbiota dysbiosis in high fat diet (HFD)-fed mice. Our study findings revealed that supplementation with fresh blueberry juice (BBJ), and fermented blueberry juice with homemade probiotic starter (FBJ) or commercial starter (CFBJ) significantly decreased fat accumulation and low density lipoprotein cholesterol (LDL-C) levels in HFD-fed mice. FBJ showed relatively more potency to reduce body weight than BBJ and CFBJ. The percentage increase in the body weight of the FBJ group was almost the same as that in the normal chow diet (NCD) group, and was approximately 10% lower than the BBJ and CFBJ groups. Overall, all blueberry juices significantly ameliorated hyperlipidemia and insulin resistance in HFD-fed mice. Moreover, the dietary interventions with BBJ, FBJ, and CFBJ for 17 weeks significantly improved the community richness and diversity of the gut microflora along with an altered structure in the HFD-fed mice group. The FBJ treated mice group showed relatively low abundance of Firmicutes, obesity-related bacteria (Oscillibacter and Alistipes), and high abundance of lean bacteria (Akkermansia, Barnesiella, Olsenella, Bifidobacterium, and Lactobacillus) compared to the HFD-fed mice group. Furthermore, BBJ and FBJ treatments regulated the liver mRNA and protein expression levels involved in lipid and glucose metabolism. This study inferred that fermented blueberry juice could be used as a functional food to prevent the modern pandemics i.e., obesity and insulin resistance.

Human microbiota modulation via QseC sensor kinase mediated in the Escherichia coli O104:H4 outbreak strain infection in microbiome model

Background

The intestinal microbiota plays a crucial role in human health, adjusting its composition and the microbial metabolites protects the gut against invading microorganisms. Enteroaggregative E. coli (EAEC) is an important diarrheagenic pathogen, which may cause acute or persistent diarrhea (≥14 days). The outbreak strain has the potent Shiga toxin, forms a dense biofilm and communicate via QseBC two-component system regulating the expression of many important virulence factors.

Results

Herein, we investigated the QseC histidine sensor kinase role in the microbiota shift during O104:H4 C227–11 infection in the colonic model SHIME® (Simulator of the Human Intestinal Microbial Ecosystem) and in vivo mice model. The microbiota imbalance caused by C227–11 infection affected ỿ-Proteobacteria and Lactobacillus spp. predominance, with direct alteration in intestinal metabolites driven by microbiota change, such as Short-chain fatty acids (SCFA). However, in the absence of QseC sensor kinase, the microbiota recovery was delayed on day 3 p.i., with change in the intestinal production of SCFA, like an increase in acetate production. The higher predominance of Lactobacillus spp. in the microbiota and significant augmented qseC gene expression levels were also observed during C227–11 mice infection upon intestinal depletion. Novel insights during pathogenic bacteria infection with the intestinal microbiota were observed. The QseC kinase sensor seems to have a role in the microbiota shift during the infectious process by Shiga toxin-producing EAEC C227–11.

Conclusions

The QseC role in C227–11 infection helps to unravel the intestine microbiota modulation and its metabolites during SHIME® and in vivo models, besides they contribute to elucidate bacterial intestinal pathogenesis and the microbiota relationships.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12866-021-02220-3.

Probiotic infant cereal improves children's gut microbiota: Insights using the Simulator of Human Intestinal Microbial Ecosystem (SHIME®)

Infant́s gut microbiota can be modulated by many factors, including mode of delivery, feeding regime, maternal diet/weight and probiotic and prebiotic consumption. The gut microbiota in dysbiosis has been associated with innumerous diseases. In this sense, early childhood intestinal microbiome modulation can be a strategy for disease prevention. This study had the purpose to evaluate the effect of an infant cereal with probiotic (Bifidobacterium animalis ssp. lactis BB-12®) on infant́s intestinal microbiota using SHIME®, which simulates human gastrointestinal conditions. The ascending colon was inoculated with fecal microbiota from three children (2-3 years old). NH₄⁺, short chain fatty acids (SCFASs) and microbiota composition were determined by selective ion electrode, GC/MS and 16S sequencing, respectively. After treatment, butyric acid production increased (p < 0.05) 52% and a decrease in NH₄⁺ production was observed (p < 0.01). The treatment stimulated an increase (p < 0.01) of Lactobacillaceae families, more precisely L. gasseri and L. kefiri. L. gasseri has been associated with the prevention of allergic rhinitis in children and L. kefiri in the prevention of obesity. Thus, infant cereal with BB-12® is able to stimulate the growth of L. gasseri and L. kefiri in a beneficial way, reducing NH₄⁺ and increasing the production of SCFAs, especially butyric acid, in SHIME®.

The role and mechanism of citrus flavonoids in cardiovascular diseases prevention and treatment

Cardiovascular diseases (CVDs) have been ranked as the leading cause of death in the world, whose global incidence is increasing year by year. Citrus, one of the most popular fruits in the world, is rich in flavonoids. Citrus flavonoids attract special attention due to a variety of biological activities, especially in the prevention and treatment of CVDs. The research progress of citrus flavonoids on CVDs have been constantly updated, but relatively fragmented, which needed to be systematically summarized. Hence, the recent research about citrus flavonoids and CVDs were reviewed, including the types and in vivo processes of citrus flavonoids, epidemiology study and mechanism on prevention and treatment of CVDs by citrus flavonoids. This review would provide a theoretical basis for the citrus flavonoids research and a new idea in the citrus industry development and application.

Impact of High-Pressure Processed Onion on Colonic Metabolism Using a Dynamic Gastrointestinal Digestion Simulator

Onions are the main dietary source of flavonols that have been associated with important health-promoting properties. Onion treated by high-pressure processing (HPP-treated onion) was subjected to a dynamic gastrointestinal digestion and colon fermentation simulator (DGID-CF) to study the effect on the gut microbiota metabolism in the three colon regions (ascending—AC, transverse—TC, and descending—DC) by means of chronic feeding with 27 g/day for 14 days. HPP-treated onion presented a high content of the flavonols quercetin-3,4’-diglucoside and quercetin-4’-glucoside, and a large percentage of them reached the AC without change. TC and DC progressively increased the total phenolic metabolites 2.5 times respective to day 2, mainly 3-hydroxyphenylacetic, 4-hydroxyphenylacetic, 3-(4-hydroxyphenyl)-propionic, and 3,4-dihydroxyphenylpropionic acids. In addition, the chronic feeding increased the beneficial colon bacteria Bifidobacterium spp. and Lactobacillus spp. and the production of total SCFAs (acetic, propionic, and butyric acids) 9 times (AC), 2.2 times (TC), and 4.4 times (DC) respective to day 1. A multivariate analysis (principal component analysis, PCA) showed a clear separation between the three colon regions based on their phenolic composition (precursors and metabolites). These results showed that HPP-treated onion modulated the human gut microbiota’s metabolism and the DGID-CF is a good system to study these changes.

Immune status, well-being and gut microbiota in military supplemented with synbiotic ice cream and submitted to field training: a randomised clinical trial

Strenuous physical activity, sleep deprivation and psychological stress are common features of military field training. The present study aimed to evaluate the effects of supplementation with a synbiotic ice cream on salivary IgA, gastrointestinal symptoms, well-being indicators and gut microbiota in young military participants undergoing field training. Sixty-five military completed the study: one group was supplemented for 30 d with synbiotic ice cream containing: 2·1 × 108 CFU/g for Lactobacillus acidophilus LA-5 and 2·7 × 109 CFU/g for Bifidobacterium animalis BB-12 and 2·3 g of inulin in the 60 g of ice cream at manufacture, and the other with a placebo ice cream. Volunteers were evaluated at pre-supplementation (baseline), post-supplementation and after a 5-d military training. Bifidobacterium and Lactobacillus genera were measured in stool samples and both showed a higher differential abundance post-supplementation and training. Salivary IgA and gastrointestinal symptoms decreased at post-training in both groups (P < 0·05; main effect of time); however, supplementation with synbiotic did not mitigate this effect. Tenseness and sleepiness were decreased in the synbiotic-treated group, but not in the placebo group at post-military training (P = 0·01 and 0·009, respectively; group × time effect). The other well-being indicators were not affected by the synbiotic supplementation. In conclusion, 30 d of synbiotic ice cream supplementation containing inulin, L. acidophilus LA-5 and B. animalis BB-12 favourably modulated gut microbiota and improved tenseness and sleepiness in healthy young military undergoing a 5-d field training. These improvements may be relevant to this population as they may influence the decision-making process in an environment of high physical and psychological stress.

Microbiota modulation and effects on metabolic biomarkers by orange juice: a controlled clinical trial

The impact of habitual orange juice consumption on microbiota, lipid and sugar metabolism was investigated in a controlled clinical trial. The clinical procedure is as follows: ten women who had a regular diet without orange juice for 30 days (OJ-free diet), followed by a regular diet plus 300 ml d-1 orange juice for 60 days (OJ-Diet), and 30 days with a regular diet without orange juice (Washout). Biochemical and dietary parameters were monitored, and blood, urine and stool samples were collected every 30 days until the end of the study. Hesperidin and naringin metabolites in the urine were identified by UHPLC, and the microbiota composition of the feces was determined by 16S rRNA. At the end of the OJ-Diet, there was a reduction in glucose (-6.5%), insulin (-33%), insulin resistance (-44%), LDL-C (-16%) and triglycerides (-30%). After the washout, these parameters returned to their initial values. There were no changes in the body weight or fat during the experimental time. The intestinal bacteria, Lactobacillus spp., Akkermansia spp., and Ruminococcus spp., increased after the intervention with orange juice. In addition, an inverse correlation was detected between these bacteria and glycemia, insulin, HOMA-IR, triglycerides, total cholesterol and LDL-C, but a direct correlation with HDL-C. In conclusion, orange juice showed a prebiotic effect, modulating the intestinal microbiota while improving the glycemia and lipid profiles.

Probiotic low-fat fermented goat milk with passion fruit by-product: In vitro effect on obese individuals' microbiota and on metabolites production

This study aimed to evaluate the impact of a two-week treatment period with probiotic low-fat fermented goat milk by Lactobacillus casei Lc-1, supplemented with passion fruit by-product (1%), on the modulation of gut microbiota from obese individuals using the Simulator of Human Intestinal Microbial Ecosystem (SHIME) system. The effects were carried out through the study of gut microbiota composition, using 16S rRNA next generation sequencing, quantification of short-chain fatty acids (SCFA) and ammonium ions. The microbiota composition changed across three vessels representing the colon regions, because of fermented milk treatment. Fermented goat milk administration caused a reduction of bacteria belonging to genera Prevotella, Megamonas and Succinivibrio, which can produce SCFA, and an increase of Lactobacillus and Bifidobacterium genera in all simulated colon regions. There was no effect on SCFA and on ammonium ions concentration during treatment period. Fermented milk shifted the obese donors' microbiota without changing metabolites production. It happens, possibly, due to a balance in abundances among bacterial genera that can produce or not SCFA, and among bacterial genera with high or low proteolytic activity. Our outcomes help to clarify the effects of the ingestion of a probiotic low-fat fermented goat milk product on colon microbiota composition.

Amoxicillin Increased Functional Pathway Genes and Beta-Lactam Resistance Genes by Pathogens Bloomed in Intestinal Microbiota Using a Simulator of the Human Intestinal Microbial Ecosystem

Antibiotics are frequently used to treat bacterial infections; however, they affect not only the target pathogen but also commensal gut bacteria. They may cause the dysbiosis of human intestinal microbiota and consequent metabolic alterations, as well as the spreading of antibiotic resistant bacteria and antibiotic resistance genes (ARGs). In vitro experiments by simulator of the human intestinal microbial ecosystem (SHIME) can clarify the direct effects of antibiotics on different regions of the human intestinal microbiota, allowing complex human microbiota to be stably maintained in the absence of host cells. However, there are very few articles added the antibiotics into this in vitro model to observe the effects of antibiotics on the human intestinal microbiota. To date, no studies have focused on the correlations between the bloomed pathogens caused by amoxicillin (AMX) exposure and increased functional pathway genes as well as ARGs. This study investigated the influence of 600 mg day-1 AMX on human intestinal microbiota using SHIME. The impact of AMX on the composition and function of the human intestinal microbiota was revealed by 16S rRNA gene sequencing and high-throughput quantitative PCR. The results suggested that: (i) AMX treatment has tremendous influence on the overall taxonomic composition of the gut microbiota by increasing the relative abundance of Klebsiella [linear discriminant analysis (LDA) score = 5.26] and Bacteroides uniformis (LDA score = 4.75), as well as taxonomic diversity (Simpson, P = 0.067, T-test; Shannon, P = 0.061, T-test), and decreasing the members of Parabacteroides (LDA score = 4.18), Bifidobacterium (LDA score = 4.06), and Phascolarctobacterium (LDA score = 3.95); (ii) AMX exposure significantly enhanced the functional pathway genes and beta-lactam resistance genes, and the bloomed pathogens were strongly correlated with the metabolic and immune system diseases gene numbers (R = 0.98, P < 0.001) or bl2_len and bl2be_shv2 abundance (R = 0.94, P < 0.001); (iii) the changes caused by AMX were "SHIME-compartment" different with more significant alteration in ascending colon, and the effects were permanent, which could not be restored after 2-week AMX discontinuance. Overall results demonstrated negative side-effects of AMX, which should be considered for AMX prescription.

Modulation of the intestinal microbiota and the metabolites produced by the administration of ice cream and a dietary supplement containing the same probiotics

The aim of the present work was to compare the capacity to modulate the intestinal microbiota and the production of metabolites after 14 d administration of a commercial dietary supplement and a manufactured ice cream, both containing the same quantity of inulin and the same viable counts of Lactobacillus acidophilus LA-5 and Bifidobacterium animalis BB-12, using the Simulator of the Human Intestinal Microbial Ecosystem (SHIME®) model. Samples of the colonic contents were evaluated microbiologically by real-time quantitative PCR (qRT-PCR) and next-generation sequencing and chemically by the production of SCFA (acetate, propionate and butyrate) and ammonium ions ($\text{NH}_4^ + $). Statistical analyses were carried out for all the variables using the two-way ANOVA followed by the Tukey multiple comparisons test (P < 0·05) for metabolite production, qRT-PCR and the bioinformatics analysis for microbiota diversity. Dietary supplement and ice cream were able to deliver the probiotic L. acidophilus and B. animalis to the simulated colon and modulate the microbiota, increasing beneficial micro-organisms such as Bifidobacterium spp., Bacteroides spp. and Faecalibacterium spp. for dietary supplement administration, and Lactobacillus spp. for ice cream supplementation. However, the ice cream matrix was probably more favourable for the maintenance of the metabolic activity of the probiotics in the SHIME® model, due to the larger amounts of acetate, propionate, butyrate and ammonium ions obtained after 14 d of supplementation. In conclusion, both ways of probiotic supplementation could be efficient, each with its own particularities.

Impact of a Plant Sterol- and Galactooligosaccharide-Enriched Beverage on Colonic Metabolism and Gut Microbiota Composition Using an In Vitro Dynamic Model

A beverage enriched with plant sterols (1 g/100 mL) and galactooligosaccharides (1.8 g/100 mL) was subjected to a dynamic gastrointestinal and colonic fermentation process to evaluate the effect on sterol metabolism, organic acid production, and microbiota composition. Production of sterol metabolites (coprostanol, methylcoprostanol, ethylcoprostenol, ethylcoprostanol, and sitostenone) was observed in the transverse colon (TC) and descending colon (DC) vessels in general, from 24 and 48 h, respectively. Microbial activity was assessed through the production of organic acids, mainly acetate in all colon vessels, lactate in the AC, and butyrate and propionate in the TC and DC. A higher diversity in the microbial community was found in the TC and DC, in accordance with a higher sterol metabolism and organic acid production. Although the prebiotic effect of galactooligosaccharides was not detected, changes in microbiota composition (an increase in the Parabacteroides genus and the Synergistaceae and Lachnospiraceae families) indicated an enhancement of sterol metabolism.

The Intestinal Fate of Citrus Flavanones and Their Effects on Gastrointestinal Health

Citrus flavanones, with hesperidin and naringin as the most abundant representatives, have various beneficial effects, including anti-oxidative and anti-inflammatory activities. Evidence also indicates that they may impact the intestinal microbiome and are metabolized by the microbiota as well, thereby affecting their bioavailability. In this review, we provide an overview on the current evidence on the intestinal fate of hesperidin and naringin, their interaction with the gut microbiota, and their effects on intestinal barrier function and intestinal inflammation. These topics will be discussed as they may contribute to gastrointestinal health in various diseases. Evidence shows that hesperidin and naringin are metabolized by intestinal bacteria, mainly in the (proximal) colon, resulting in the formation of their aglycones hesperetin and naringenin and various smaller phenolics. Studies have also shown that citrus flavanones and their metabolites are able to influence the microbiota composition and activity and exert beneficial effects on intestinal barrier function and gastrointestinal inflammation. Although the exact underlying mechanisms of action are not completely clear and more research in human subjects is needed, evidence so far suggests that citrus flavanones as well as their metabolites have the potential to contribute to improved gastrointestinal function and health.

Are Fruit Juices Healthier Than Sugar-Sweetened Beverages? A Review

Free sugars overconsumption is associated with an increased prevalence of risk factors for metabolic diseases such as the alteration of the blood lipid levels. Natural fruit juices have a free sugar composition quite similar to that of sugar-sweetened beverages. Thus, could fruit juice consumption lead to the same adverse effects on health as sweetened beverages? We attempted to answer this question by reviewing the available evidence on the health effects of both sugar-sweetened beverages and natural fruit juices. We determined that, despite the similarity of fruits juices to sugar-sweetened beverages in terms of free sugars content, it remains unclear whether they lead to the same metabolic consequences if consumed in equal dose. Important discrepancies between studies, such as type of fruit juice, dose, duration, study design, and measured outcomes, make it impossible to provide evidence-based public recommendations as to whether the consumption of fruit juices alters the blood lipid profile. More randomized controlled trials comparing the metabolic effects of fruit juice and sugar-sweetened beverage consumption are needed to shape accurate public health guidelines on the variety and quantity of free sugars in our diet that would help to prevent the development of obesity and related health problems.

Chinese yam (Dioscorea opposita Thunb.) alleviates antibiotic-associated diarrhea, modifies intestinal microbiota, and increases the level of short-chain fatty acids in mice

Antibiotic-associated diarrhea (AAD) is a common adverse effect of antibiotic treatment. The study was to evaluate effects of Chinese yam (Dioscorea opposita Thunb.) on AAD, and changes of intestinal microbiota and short-chain fatty acids (SCFA). AAD model was established using Balb/c mice by gavage with ampicillin for 5 days, followed by a 10-day administration of low, medium, and high dosage of Chinese yam, containing allantoin (4.35 mg/g) and polysaccharides (85.51 mg/g). The results showed that Chinese yam accelerated the recovery from acute diarrhea, reverse AAD-induced body weight loss and cecal enlargement. The high-dosage Chinese yam increased probiotic Bifidobacteria and Lactobacilli by 47% and 21% and decreased potential pathogen Enterococcus and Clostridium perfringens by 8% and 27% on day 15 (P < .05). Bacterial community analysis revealed that Chinese yam contributed to repair the ampicillin-induced intestinal microbiota disorder, enrich the abundance of Bacteroides spp. and Clostridium spp. Additionally, Chinese yam supplementation increased the production of SCFA.

Daily Consumption of Orange Juice from Citrus sinensis L. Osbeck cv. Cara Cara and cv. Bahia Differently Affects Gut Microbiota Profiling as Unveiled by an Integrated Meta-Omics Approach

We have investigated the effect of intake of two different orange juices from Citrus sinensis cv. "Cara Cara" and cv. "Bahia" on faecal microbiota and metabolome using an integrated meta-omics approach. Following a randomized crossover design, healthy subjects daily consumed 500 mL of orange juice from Cara Cara or Bahia juices or an isocaloric control drink. Stools were collected at baseline (T0) and after a week (T7) of intervention. Operational taxonomic units (OTUs) were pyrosequenced targeting 16S rRNA, and faecal metabolites were analyzed by an untargeted metabolomics approach based on ¹H NMR spectroscopy. The major shift observed in microbiota composition after orange juice intake was the increased abundance of a network of Clostridia OTUs from Mogibacteriaceae, Tissierellaceae, Veillonellaceae, Odoribacteraceae, and Ruminococcaceae families, whose members were differently affected by Cara Cara or Bahia juice consumption. A core of six metabolites such as inositol, choline, lysine, arginine, urocanic acid, and formate significantly increased in Cara Cara compared to the Bahia group.

Effect of Daily Consumption of Orange Juice on the Levels of Blood Glucose, Lipids, and Gut Microbiota Metabolites: Controlled Clinical Trials

Ingestion of bioactive compounds, such as hesperidin and naringin, found in citrus fruits and orange juice, can improve the homeostasis of gut microbiota. A controlled clinical study with temporal series intergroup design with 10 apparently healthy women (28.5 ± 8.4 years, 24.1 ± 3.3 kg/m²) were evaluated after continuous consumption of commercial pasteurized orange juice for 2 months. Samples of blood serum and stool were collected at basal time and periodically during the experiment for biochemical and microbiology assays. Intestinal microbiota was evaluated for total anaerobic bacteria, Lactobacillus spp., Bifidobacterium spp., and Clostridium spp. An independent culture evaluation was performed using Denaturing Gradient Gel Electrophoresis (DGGE). The pH, ammonium (NH₄⁺), and short-chain fatty acids (SCFAs) were evaluated for microbial metabolism. The results showed that daily intake of orange juice did not change women's body composition, but improved blood biochemical parameters, such as low-density lipoprotein-cholesterol, glucose, and insulin sensitivity. Orange juice positively modulated the composition and metabolic activity of microbiota, increasing the population of fecal Bifidobacterium spp. and lactobacillus spp. Polymerase chain reaction-DGGE of microbiota showed similar composition of total bacteria, and microbial metabolism showed a reduction of ammonia and an increase of the production of SCFAs. These results suggested that a daily consumption of orange had a positive effect on the intestinal microbiota and metabolic biomarkers of young women, which may be an effective alternative for a healthy drink.

The Therapeutic Potential of Naringenin: A Review of Clinical Trials

Naringenin is a flavonoid belonging to flavanones subclass. It is widely distributed in several Citrus fruits, bergamot, tomatoes and other fruits, being also found in its glycosides form (mainly naringin). Several biological activities have been ascribed to this phytochemical, among them antioxidant, antitumor, antiviral, antibacterial, anti-inflammatory, antiadipogenic and cardioprotective effects. Nonetheless, most of the data reported have been obtained from in vitro or in vivo studies. Although some clinical studies have also been performed, the main focus is on naringenin bioavailability and cardioprotective action. In addition, these studies were done in compromised patients (i.e., hypercholesterolemic and overweight), with a dosage ranging between 600 and 800 μM/day, whereas the effect on healthy volunteers is still debatable. In fact, naringenin ability to improve endothelial function has been well-established. Indeed, the currently available data are very promising, but further research on pharmacokinetic and pharmacodynamic aspects is encouraged to improve both available production and delivery methods and to achieve feasible naringenin-based clinical formulations.

Body Mass Index as a Determinant of Systemic Exposure to Gallotannin Metabolites during 6-Week Consumption of Mango (Mangifera indica L.) and Modulation of Intestinal Microbiota in Lean and Obese Individuals

SCOPE

This human clinical pilot trial investigated pharmacokinetics of gallotannin-metabolites and modulation of intestinal microbiota in healthy lean and obese individuals after 6 weeks of daily mango consumption.

METHODS AND RESULTS

Participants are divided into three groups: Lean Mango (LM: n = 12; BMI = 22.9 kg m^-2 ), Obese Mango (OM: n = 9; BMI = 34.6 kg m^-2 ), and Lean Control (LC: n = 11; BMI = 22.1 kg m^-2 ). LM and OM consumed 400 g of mango per day for 6 weeks. LC consumed mango only on Days 0 and 42. After 6 weeks, LM experienced increased systemic exposure (AUC_0-8h ) to gallotannin-metabolites, 1.4-fold (p = 0.043). The greatest increase is 4-O-methyl-gallic acid, 3.3-fold (p = 0.0026). Cumulative urinary excretion of gallotannin-metabolites significantly increased in LM and OM, but not LC. For OM, qPCR data show increased levels of tannase-producing Lactococcus lactis and decreased levels of Clostridium leptum and Bacteroides thetaiotaomicron, bacteria associated with obesity. LM experienced an increased trend of fecal levels of butyric (1.3-fold; p = 0.09) and valeric acids (1.5-fold; p = 0.056). Plasma endotoxins showed a decreased trend in LM and OM.

CONCLUSION

Continuous mango intake significantly increased systemic exposure to gallotannin- metabolites and induced an increased trend for fecal short-chain fatty acids in lean but not obese individuals. This pharmacokinetic discrepancy may result in BMI-associated reduced gallotannin-derived health benefits.

In Vitro Ecological Response of the Human Gut Microbiome to Bioactive Extracts from Edible Wild Mushrooms

This study presents the effect of two new products based on atomized extracts from edible wild mushrooms (RoBioMush1, RoBioMush2) on the microbiota of three target groups: clinically healthy (NG) individuals, individuals with nutritional disorders (ND), and individuals with cardiovascular diseases (CVD). The microbiota fingerprints were determined by quantitative polymerase chain reaction (qPCR). Modulations in the simulated microbiome were established and correlated with the presence of phenolic compounds released in the in vitro environment (a three-stage culture system GIS2 simulator, www.gissystems.ro). The high metabolizing capacity of NG and CVD correlated positively with the rest of the biological activities expressed in vitro. ND microbiota consumed a wide spectrum of monosaccharides from the products. Xylose was present in large quantities in the descending segment (minimum: 175 μg/mL for ND). The primary conclusion was that the microbiological ecosystem was modulated, as proven by the presence of specific biomarkers (e.g., ammonium levels and fingerprints of short-chain fatty acids–SCFAs), which stimulate the organism’s health status and were correlated with the restoration of a normal microbiota fingerprint.

Amalgamation of polyphenols and probiotics induce health promotion

The residing microbiome with its vast repertoire of genes provide distinctive properties to the host by which they can degrade and utilise nutrients that otherwise pass the gastro-intestinal tract unchanged. The polyphenols in our diet have selective growth promoting effects which is of utmost importance as the state of good health has been linked to dominance of particular microbial genera. The polyphenols in native form might more skilfully exert anti-oxidative and anti-inflammatory properties but in a living system it is the microbial derivatives of polyphenol that play a key role in determining health outcome. This two way interaction has invoked great interest among researchers who have commenced several clinical surveys and numerous studies in in-vitro, simulated environment and living systems to find out in detail about the biomolecules involved in such interaction along with their subsequent physiological benefits. In this review, we have thoroughly discussed these studies to develop a fair idea on how the amalgamation of probiotics and polyphenol has an immense potential as an adjuvant therapeutic for disease prevention as well as treatment.

Influence of polyphenol rich seabuckthorn berries juice on release of polyphenols and colonic microbiota on exposure to simulated human digestion model

The present study investigated the effect of polyphenol rich Sea buckthorn berries juice (SBJ) on colonic microbial composition and diversity using in vitro simulated gut model. The release of polyphenols, their antioxidant activity and impact on microbial diversity was evaluated under long term fermentation for 21 days. The treatment of colonic reactors with basal feed supplemented with SBJ resulted in an increase in population and diversity of beneficial bacteria as revealed by viable cell count and PCR-DGGE. A higher release of phenolics was observed, which resulted in higher antioxidant activity in the colonic reactors throughout the treatment period (p < 0.05). Higher content of resveratrol, rutin and chlorogenic acid were observed in ascendens colon whereas quercetin, ferulic and caeffic acid level were higher in descendens colon due to biotransformation of polyphenols in the later part of colon. The Principal Component Analysis also indicated the stimulatory effect of SBJ on the beneficial microbial population of Lactobacilli, Bacteroides/Prevotella and Bifidobacteria in all the three reactors. It also confirmed higher release of polyphenolic compounds and associated antioxidant activities in descendens colon.

An exploratory study on the effect of daily fruits and vegetable juice on human gut microbiota

In order to evaluate the effect of daily consumption of fruit and vegetable juice on the human intestinal microbial community, we compared changes in the gut microbiota and extracellular vesicles in human feces and bowel, and skin symptoms at the baseline and 3 weeks post juice consumption of 22 participants. After 3 weeks of juice consumption, a significant increase in the richness of microbiota (α-diversity, P < 0.05) was observed. It was accompanied by an abundance in Faecalibacterium (bacterial: from 1.62 ± 0.80% to 2.14 ± 0.72% and extra vesicle: 2.49 ± 1.49% to 6.06 ± 3.07%; P < 0.05 in all cases). At the end of the study period, there were reductions in body weight regardless of sex (P < 0.05) and improvements of the symptoms including diarrhea, constipation, fatigue, and skin problems. Eating fruits and vegetables could help modulate the profile of the fecal microbiota and alleviate bowel and skin troubles, and fatigue.

High intake of orange juice and cola differently affects metabolic risk in healthy subjects

BACKGROUND

Higher consumption of sugar-containing beverages has been associated with an elevated risk of type 2 diabetes and gout. Whether this equally applies to cola with an unhealthy image and orange juice (OJ) having a healthy image remains unknown.

METHODS

In order to investigate whether OJ and cola differently affect metabolic risk 26 healthy adults (24.7 ± 3.2 y; BMI 23.2 ± 3.3 kg/m²) participated in a 2 × 2-wk intervention and consumed either OJ or caffeine-free cola (20% Ereq as sugar from beverages) in-between 3 meals/d at ad libitum energy intake. Glycemic control, uric acid metabolism and gut microbiota were assessed as outcome parameters.

RESULTS

Fecal microbiota, body weight, basal and OGTT-derived insulin sensitivity remained unchanged in both intervention periods. Levels of uric acid were normal at baseline and did not change with 2-wk cola consumption (-0.03 ± 0.67 mg/dL; p > 0.05), whereas they decreased with OJ intervention (-0.43 ± 0.56 mg/dL; p < 0.01) due to increased uric acid excretion (+130.2 ± 130.0 mg/d; p < 0.001). Compared to OJ, consumption of cola led to a higher daylong glycemia (ΔiAUC: 36.9 ± 83.2; p < 0.05), an increase in glucose variability (ΔMAGE-Index: 0.29 ± 0.44; p < 0.05), and a lower 24 h-insulin secretion (ΔC-peptide excretion: -31.76 ± 38.61 μg/d; p < 0.001), which may be explained by a decrease in serum potassium levels (-0.11 ± 0.24 mmol/L; p < 0.05).

CONCLUSION

Despite its sugar content, regular consumption of large amounts of OJ do not increase the risk of gout but may even contribute to lower uric acid levels. The etiology of impaired insulin secretion with cola consumption needs to be further investigated.

Impact of multi-functional fermented goat milk beverage on gut microbiota in a dynamic colon model

The aim of this research was to evaluate the effect of grape probiotic fermented beverages made of goat milk, with or without added grape pomace on gut microbiota in a Simulator of Human Intestinal Microbial Ecosystem (SHIME®). SHIME® model was used to investigate to assess changes in microbial composition and fermentation metabolites (short- and branched-chain fatty acids and ammonium), as well as under the antioxidant capacity. The results demonstrated that the beverages formulated, with or without grape pomace extract, exhibited high dietary fiber, oleic acid, phenolic compounds content and antioxidant activity. Both beverages also kept L. rhamnosus and S. thermophilus viable during their passage through the intestinal tract and had a positive effect on gut microbiota metabolism, increasing the antioxidant capacity and the production of short-chain fatty acids, and decreasing the ammonium concentration. Therefore, the multifunctional beverages formulated in this study can offer a new perspective for the production of foods with positive potential effects on human health.

Tissue-Associated Bacterial Alterations in Rectal Carcinoma Patients Revealed by 16S rRNA Community Profiling

Sporadic and inflammatory forms of colorectal cancer (CRC) account for more than 80% of cases. Recent publications have shown mechanistic evidence for the involvement of gut bacteria in the development of both CRC-forms. Whereas, colon and rectal cancer have been routinely studied together as CRC, increasing evidence show these to be distinct diseases. Also, the common use of fecal samples to study microbial communities may reflect disease state but possibly not the tumor microenvironment. We performed this study to evaluate differences in bacterial communities found in tissue samples of 18 rectal-cancer subjects when compared to 18 non-cancer controls. Samples were collected during exploratory colonoscopy (non-cancer group) or during surgery for tumor excision (rectal-cancer group). High throughput 16S rRNA amplicon sequencing of the V4-V5 region was conducted on the Ion PGM platform, reads were filtered using Qiime and clustered using UPARSE. We observed significant increases in species richness and diversity in rectal cancer samples, evidenced by the total number of OTUs and the Shannon and Simpson indexes. Enterotyping analysis divided our cohort into two groups, with the majority of rectal cancer samples clustering into one enterotype, characterized by a greater abundance of Bacteroides and Dorea. At the phylum level, rectal-cancer samples had increased abundance of candidate phylum OD1 (also known as Parcubacteria) whilst non-cancer samples had increased abundance of Planctomycetes. At the genera level, rectal-cancer samples had higher abundances of Bacteroides, Phascolarctobacterium, Parabacteroides, Desulfovibrio, and Odoribacter whereas non-cancer samples had higher abundances of Pseudomonas, Escherichia, Acinetobacter, Lactobacillus, and Bacillus. Two Bacteroides fragilis OTUs were more abundant among rectal-cancer patients seen through 16S rRNA amplicon sequencing, whose presence was confirmed by immunohistochemistry and enrichment verified by digital droplet PCR. Our findings point to increased bacterial richness and diversity in rectal cancer, along with several differences in microbial community composition. Our work is the first to present evidence for a possible role of bacteria such as B. fragilis and the phylum Parcubacteria in rectal cancer, emphasizing the need to study tissue-associated bacteria and specific regions of the gastrointestinal tract in order to better understand the possible links between the microbiota and rectal cancer.