In-vitro assessment of the effects of dietary fibers on microbial fermentation and communities from large intestinal digesta of pigs

Unveiling the potential of linseed mucilage, its health benefits, and applications in food packaging

Industrial waste products derived from the oil industry often contain valuable substances and elements with great potential. These by-products can be used for various purposes, including as nutrients, bioactive compounds, fuels, and polymers. Linseed mucilage (LM) is one such example of a beneficial by-product obtained from linseed. It possesses favorable chemical and functional properties, depending on its method of extraction. Different pretreatments, such as enzymatic extraction, microwave-assisted extraction, pulse electric field, and ultrasound-assisted extraction, have been explored by various researchers to enhance both the yield and quality of mucilage. Furthermore, LM has exhibited therapeutic effects in the treatment of obesity, diabetes, constipation, hyperlipidemia, cancer, and other lifestyle diseases. Additionally, it demonstrates favorable functional characteristics that make it suitable to be used in bioplastic production. These properties preserve food quality, prolong shelf life, and confer antimicrobial activity. It also has the potential to be used as a packaging material, especially considering the increasing demand for sustainable and biodegradable alternatives to plastics because of their detrimental impact on environmental health. This review primarily focuses on different extraction techniques used for linseed mucilage, its mechanism of action in terms of health benefits, and potential applications in food packaging.

Estimating the contribution of the porcine fecal core microbiota to metabolite production via mathematical modeling and in vitro fermentation

The swine gut microbiota is a complex ecosystem found throughout the gastrointestinal tract, with multiple exchanges with the host and whose composition is linked to both external and internal factors, such as diet or breed. Diet, probiotic, or prebiotic interventions have been designed to boost beneficial host-microbiota interactions, such as the production of anti-inflammatory molecules, or the fermentation of otherwise undigested resources. In parallel, a smaller microbial population, shared among the same host species, independent of external or internal factors, has been described and defined as the "core microbiota." Therapies targeting the core microbiota could possibly lead to more precise and long-lasting effects. However, the metabolic role of the porcine core microbiota, especially in relation to the rest of the microbial community, is currently missing. We present here the first dynamic model of the porcine core microbiota, which we used to estimate the core-microbiota metabolite production and to forecast the effect of a synbiotic intervention targeting the core genera of the core microbiota. We developed a community model in which a total of 17 microbial groups were established based on culture-based information of representative species. First, the model parameters were estimated, and the resulting model simulations were compared favorably with in vitro experimentation. The model was then used to predict the microbial dynamics of the core and non-core members under different experimental conditions. Therefore, it was able to theorize the main-metabolite core microbiota contribution, hypothesizing that it could be mainly responsible for acetate and propionate, but not for butyrate production.IMPORTANCECurrently, little information is present in the literature to describe the generic metabolic role of the porcine core microbiota or to inform on the effect of interventions targeting the core genera. Moreover, both in vitro and in vivo experimentations aiming to explore the core microbiota dynamics are technically demanding, expensive, or restricted by ethical considerations. Modeling approaches can be used as an initial exploratory tool to develop hypotheses for targeted experimentation. Our mathematical model provides initial information on the microbial and metabolite dynamics of the core microbiota in relation to diet and therapeutic intervention.

Establishment of porcine fecal-derived ex vivo microbial communities to evaluate the impact of livestock feed on gut microbiome

Sustainable livestock production requires reducing competition for food and feed resources and increasing the utilization of food by-products in livestock feed. This study describes the establishment of an anaerobic batch culture model to simulate pig microbiota and evaluate the effects of a food by-product, wakame seaweed stalks, on ex vivo microbial communities. We selected one of the nine media to support the growth of a bacterial community most similar in composition and diversity to that observed in pig donor feces. Supplementation with wakame altered the microbial profile and short-chain fatty acid composition in the ex vivo model, and a similar trajectory was observed in the in vivo pig experimental validation. Notably, the presence of wakame increased the abundance of Lactobacillus species, which may have been due to cross-feeding with Bacteroides. These results suggest the potential of wakame as a livestock feed capable of modulating the pig microbiome. Collectively, this study highlights the ability to estimate the microbiome changes that occur when pigs are fed a specific feed using an ex vivo culture model.

Effects of Varying Levels of Wheat Bran Dietary Fiber on Growth Performance, Fiber Digestibility and Gut Microbiota in Erhualian and Large White Pigs

To evaluate the tolerance of a high-fiber diet in Erhualian pigs (Er-HL), the present investigation systematically investigated the ramifications of varying wheat bran fiber levels, specified as total dietary fiber (TDF) values of 14.07%, 16.32%, 17.99%, and 18.85%, on growth performance, fiber digestibility and gut microbiota in Er-HL, large Large White pigs (L-LW, the same physiological stage as the Er-HL) and small Large White pigs (S-LW, the same body weight as the Er-HL). Our results revealed that fiber levels exerted no discernable impact on growth performance (average daily feed intake (ADFI), and average daily gain (ADG)) of Er-HL (p > 0.05). Conversely, L-LW exhibited a decrease in ADFI and ADG with increasing fiber levels (p < 0.05). Notably, the apparent total tract digestibility (ATTD) of various fiber components, including neutral detergent fiber (NDF), acid detergent fiber (ADF), hemicellulose, TDF and insoluble dietary fiber (IDF), in Er-HL were significantly higher than those in S-LW and L-LW irrespective of diets (p < 0.05). The ATTD of cellulose and hemicellulose in Er-HL significantly decreased with increasing fiber levels (p < 0.05), yet remained statistically indifferent when comparing the 7%-wheat-bran-replaced diet (7% WRB, TDF 16.32%) to the basal diet (TDF 14.07%) (p > 0.05). The cecal microbiota of Er-HL had higher richness estimators (Chao1 and ACE) than those of S-LW and L-LW irrespective of diets (p < 0.01). Breed serves as a pivotal determinant in shaping swine gut microbiota. Thirteen genera were selected as the key bacteria related to high fiber digestibility of Er-HL. Further functional examination of these key genera elucidated an enrichment of pathways pertinent to carbohydrate metabolism in Er-HL samples compared with S-LW and L-LW samples. In summary, Er-HL exhibited high-fiber tolerance both in terms of growth performance and fiber digestibility compared with Large White pigs. Specifically, the ATTD of NDF, ADF, hemicellulose, IDF and TDF were significantly higher in Er-HL compared with L-LW and S-LW, irrespective of diets. Fiber level exerted no discernable impact on growth performance (ADFI, ADG) and the ATTD of fiber (NDF, ADF, IDF and TDF) in Er-HL. The optimum fiber level of the Er-HL was identified as 7% WRB (TDF 16.32%). Thirteen genera were ascertained to significantly contribute to high fiber digestibility of Er-HL, correlating with an enhancement of carbohydrate metabolism pathways.

Relationship between Oat Consumption, Gut Microbiota Modulation, and Short-Chain Fatty Acid Synthesis: An Integrative Review

The gut microbiota consists of a set of microorganisms that colonizes the intestine and ferment fibers, among other nutrients, from the host's diet. A healthy gut microbiota, colonized mainly by beneficial microorganisms, has a positive effect on digestion and plays a role in disease prevention. However, dysregulation of the gut microbiota can contribute to various diseases. The nutrition of the host plays an important role in determining the composition of the gut microbiota. A healthy diet, rich in fiber, can beneficially modulate the gut microbiota. In this sense, oats are a source of both soluble and insoluble fiber. Oats are considered a functional ingredient with prebiotic potential and contain plant proteins, unsaturated fats, and antioxidant compounds. The impact of oat consumption on the gut microbiota is still emerging. Associations between oat consumption and the abundance of Akkermansia muciniphila, Roseburia, Lactobacillus, Bifidobacterium, and Faecalibacterium prausnitzii have already been observed. Therefore, this integrative review summarizes the findings from studies on the relationship between oat consumption, the gut microbiota, and the metabolites, mainly short-chain fatty acids, it produces.

Effect of the inclusion of extruded flaxseed in the diet of fattening pigs on performance parameters and blood parameters

The aim of the study was to determine the effect of the inclusion of 2%, 4% and 6% extruded flaxseed in the diet of fattening pigs on their growth performance parameters, carcass parameters, and selected blood parameters. The experiment was conducted on 160 weaners (from about 30 kg to about 110 kg BW) assigned to four experimental groups of 40 animals each (5 replicates with 8 individuals each). The animals in control group received a diet in which the source of fat was soybean oil. The other groups received extruded flaxseed (FE) in place of soybean meal in the amount of 2% (group 2FE); 4% (group 4FE) and 6% (group 6FE). Soybean oil was added to the diets in the experimental treatments to obtain equal amounts of fat. The inclusion of 2% and 4% extruded flaxseed in the diet of fatteners in place of soybean meal significantly improved the digestibility of basic nutrients, i.e. ether extract (by about 5%) and dietary fibre (by more than 20%) and led to better growth performance (higher BW by about 11%; higher ADG by about 20% and lower FCR by about 12%) vs group C. In the groups with 2% and 4% extruded flaxseed there was also an increase in the lean meat content of the carcasses (by about 6%) and the thickness of the backfat (by about 6.5%) vs group C. The inclusion of extruded flaxseed did not affect the animals' condition, as indicated by the haematological and biochemical parameters of the blood, which were within reference ranges. The results for production, nutrient digestibility and carcass analysis between groups 2FE and 4FE were similar, and at this stage of research indicate that the use of 2% extruded flaxseed is economically more justified.

Sanitary Conditions on the Farm Alters Fecal Metabolite Profile in Growing Pigs

The aim of this study was to use fecal metabolite profiling to evaluate the effects of contrasting sanitary conditions and the associated subclinical health status of pigs. We analyzed fecal metabolite profiles by nuclear magnetic resonance (1H NMR) from pigs aged 14 and 22 weeks. Pigs kept under low and high sanitary conditions differed in fecal metabolites related to the degradation of dietary starch, metabolism of the gut microbiome, and degradation of components of animal (host) origin. The metabolites that differed significantly (FDR < 0.1) were from metabolic processes involved in either maintaining nutrient digestive capacity, including purine metabolism, energy metabolism, bile acid breakdown and recycling, or immune system metabolism. The results show that the fecal metabolite profiles reflect the sanitary conditions under which the pigs are kept. The fecal metabolite profiles closely resembled the profiles of metabolites found in the colon of pigs. Fecal valerate and kynurenic acid could potentially be used as “non-invasive” biomarkers of immune or inflammatory status that could form the basis for monitoring subclinical health status in pigs.

Alteration of Porcine Intestinal Microbiota in Response to Dietary Manno-Oligosaccharide Supplementation

Manno-oligosaccharide (MOS) is a prebiotic derived from natural plants or yeasts. Here, we explored the response of intestinal microbiota and epithelial functions after ingestion of MOS in a porcine model. Sixteen pigs were randomly assigned into two treatments and fed with basal or MOS-containing (0.3% MOS) diet for 21 days. Results showed that MOS supplementation increased the cecal acetate content and ileal 16S rRNA gene copies (p < 0.05). Importantly, MOS decreased the abundance of phylum Proteobacteria in cecal digesta (p < 0.05). Moreover, MOS elevated the expression level of SCL5A8 and GPR109A but decreased the expression levels of HDAC1 and TNF-α in the ileal and cecal mucosa (p < 0.05). MOS upregulated the expression levels of tight-junction protein (ZO-1, claudin-1, and occludin) and IGF-1 in the ileum and cecum (p < 0.05). This study presents the alteration of intestinal microbiota composition and intestinal barrier function after MOS administration, and facilitates our understanding of the mechanisms behind the dietary MOS-modulated intestinal microbiota and health.

Sanitary Conditions Affect the Colonic Microbiome and the Colonic and Systemic Metabolome of Female Pigs

Differences in sanitary conditions, as model to induce differences in subclinical immune stimulation, affect the growth performance and nutrient metabolism in pigs. The objective of the present study was to evaluate the colonic microbiota and the colonic and systemic metabolome of female pigs differing in health status induced by sanitary conditions. We analyzed blood and colon digesta metabolite profiles using Nuclear Magnetic Resonance (1H NMR) and Triple quadrupole mass spectrometry, as well as colonic microbiota profiles. 1H NMR is a quantitative metabolomics technique applicable to biological samples. Weaned piglets of 4 weeks of age were kept under high or low sanitary conditions for the first 9 weeks of life. The microbiota diversity in colon digesta was higher in pigs subjected to low sanitary conditions (n = 18 per treatment group). The abundance of 34 bacterial genera was higher in colon digesta of low sanitary condition pigs, while colon digesta of high sanitary status pigs showed a higher abundance for four bacterial groups including the Megasphaera genus (p < 0.003) involved in lactate fermentation. Metabolite profiles (n = 18 per treatment group) in blood were different between both groups of pigs. These different profiles suggested changes in general nutrient metabolism, and more specifically in amino acid metabolism. Moreover, differences in compounds related to the immune system and responses to stress were observed. Microbiome-specific metabolites in blood were also affected by sanitary status of the pigs. We conclude that the microbiome composition in colon and the systemic metabolite profiles are affected by sanitary conditions and related to suboptimal health. These data are useful for exploring further relationships between health, metabolic status and performance and for the identification of biomarkers related to health (indices) and performance.

Effect of dietary fiber fermentation on short-chain fatty acid production and microbial composition in vitro

BACKGROUND

The efficient utilization of fiber-rich co-products is important for optimizing feed resource utilization and animal health. This study was conducted to evaluate the fermentation characteristics of fiber-rich co-products, which had equal quantities of total dietary fiber (TDF), at different time points using batch in vitro methods. It considered their gas production, short-chain fatty acid (SCFA) production, and microbial composition.

RESULTS

The fermentation of wheat bran (WB) and oat bran (OB) showed higher and faster (P < 0.05) gas and SCFA production than corn bran (CB), sugar beet pulp (SBP), and soybean hulls (SH). The α-diversity was higher in the CB, SBP, and SH groups than in the WB and OB groups (P < 0.05). At the phylum level, OB and WB fermentation showed lower (P < 0.05) relative abundance of Actinobacteria than the CB, SBP, and SH groups. At the genus level, OB and WB fermentation increased the Enterococcus population in comparison with the CB, SBP, and SH groups, whereas CB and SBP fermentation improved the relative abundance of the Christensenellaceae R-7 group more than the WB, OB, and SH groups (P < 0.05).

CONCLUSION

Overall, WB and OB were rapidly fermented by fecal microbiota, in contrast with SBP, SH, and CB. Fermentation of different fiber-rich co-products with an equal TDF content gives different responses in terms of microbial composition and SCFA production due to variations in their physicochemical properties and molecular structure. © 2020 Society of Chemical Industry.

Development and validation of the Simulator of the Canine Intestinal Microbial Ecosystem (SCIME)1

Whereas a wide variety of in vitro models have been developed and validated to assess the effect of specific food ingredients on the human gut microbiome, such models have only been developed and applied to a limited extent for companion animals. Since the use of pre- and probiotics to improve gut health is an emerging research topic in the field of companion animals and as dogs are often used as laboratory animals in developing and testing of pharmaceuticals, the current study aimed to establish an adequate canine in vitro model. This consisted of a four-stage reactor composed of a stomach and small intestinal compartment followed by a proximal and distal colon. This semi-continuous gastrointestinal tract model allowed a long-term, region-dependent, and pH-controlled simulation of the colon-associated microbial community of dogs. Upon reaching a functional steady state, the simulated canine microbial community composition proved to be representative of the in vivo situation. Indeed, the predominant bacterial phyla present in the in vitro proximal and distal colon corresponded with the main bacterial phyla detected in the fecal material of the dogs, resulting in an average community composition along the simulated canine gastrointestinal tract of 50.5% Firmicutes, 34.5% Bacteroidetes, 7.4% Fusobacteria, 4.9% Actinobacteria, and 2.7% Proteobacteria. A parallel in vivo-in vitro comparison assessing the effects of fructooligosaccharides (FOS) on the canine microbial community composition showed a consistent stimulation of Lactobacillus concentrations in the in vivo fecal samples as well as in the in vitro canine gut model. Furthermore, the in vitro platform provided additional insights about the prebiotic effect of FOS supplementation of dogs, such as a reduced abundance of Megamonas spp. which are only present in very low abundance in in vivo fecal samples, indicating an interesting application potential of the developed canine in vitro model in research related to gastrointestinal health of dogs.

Microbial Mechanistic Insights into the Role of Sweet Potato Vine on Improving Health in Chinese Meishan Gilt Model

Simple Summary

Sweet potato vine as a source of fiber had been used in China for many years. We investigated the effects of fresh sweet potato vine on intestinal and plasma metabolites as well as colon microbial composition in Chinese Meishan gilts. Results suggest that sweet potato vine promoted intestinal muscle development, decreased gut permeability, endotoxin and pro-inflammatory cytokines concentrations, and increased butyrate production as well as beneficial flora, thus improving gut health.

Abstract

This study explored the impact of fresh sweet potato vine on the growth as well as the metabolites and colon microbial composition in Chinese Meishan gilt. Twenty Meishan gilts (body weight 30 ± 0.18 kg, n = 10 per treatment) were randomly assigned to a control (CON) or sweet potato vine (SPV) supplementation diet treatment. Gilts were housed in individual stalls. In the SPV treatment, 2 kg fresh sweet potato vine was used instead of 0.18 kg basal diet which provided the same amount of digestive energy and crude protein with the exception of crude fiber (CON, 51.00 g/d vs. SPV, 73.94 g/d) in terms of dry matter intake. Gilts were slaughtered and samples were collected on day 19 after the third estrus cycle. The SPV treatment tended to increase slaughter weight of gilts (p = 0.07); it also increased (p < 0.05) gastrointestinal tract weight and intestinal muscle layer thickness. SPV treatment also decreased (p < 0.05) carcass yield and subcutaneous adipose tissue. The concentration of zonulin and endotoxin in plasma was decreased (p < 0.05) as the gilt consumed the SPV diet. Colonic fecal concentrations of endotoxin, lipocalin-2, and tumor necrosis factor-α (TNF-α) were decreased (p < 0.05), and interleukin-10 (IL-10) was increased (p < 0.05) in the SPV treatment. Butyric acid and acetate concentration in colonic content as well as acetate concentration in caecal content were increased (p < 0.05) in the SPV treatment. Furthermore, the expression of carnitine palmityl transferase (CPT-1) and peroxisome proliferator-activated receptor-α (PPAR-α) in gilt liver in SPV treatment was increased (p < 0.05) in comparison with CON treatment. Meanwhile, the composition of the colon microbes was also altered by SPV; representative changes included an increase in Lactobacillus, Bacteroides, Roseburia, and Lachnospira. These results indicate that gilt fed with sweet potato vine had decreased gut permeability, endotoxin and pro-inflammatory cytokines concentrations; colonic fecal microbiota was also changed, which may be further beneficial to the intestinal health of Chinese Meishan gilt.

The effect of Lactobacillus acidophilus and Lactobacillus casei on the in vitro bioaccessibility of flaxseed lignans (Linum usitatissimum L.)

Secoisolariciresinol (SECO) is present in flaxseeds as a glucoside, secoisolariciresinol diglucoside (SDG), which can be metabolized to enterodiol (ED) and enterolactone (EL) by the human intestinal microbiota. The aim of this study was to evaluate the effect of Lactobacillus casei and Lactobacillus acidophilus on the bioaccessibility of flaxseed lignans from a complete in vitro digestion of whole flaxseeds (WFs) and flaxseed flour (FF). Lignans are only detected in the large intestine. The bioaccessibility of SDG for FF digestion can be ordered as follows: control (without probiotics) > L. casei > L. acidophilus; and for WF digestion, only in the presence of L. casei SDG was detected. For SECO and EL, the presence of both probiotics had no effect on FF and WF digestion. However, in the digestion of WF both L. casei and L. acidophilus increased ED bioaccessibility in the first 12 h; but both probiotics had no significant effect on FF digestion.

Digestion under saliva, simulated gastric and small intestinal conditions and fermentation in vitro of polysaccharides from the flowers of Camellia sinensis induced by human gut microbiota

In the present study, digestion under saliva, simulated gastric and small intestinal conditions and fermentation in vitro of polysaccharides from the flowers of Camellia sinensis (TFPS) by human gut microbiota were investigated. The results indicated that human saliva and simulated gastric and intestinal juices had no effect on TFPS, while TFPS could be utilized by human fecal microbiota, which was proved from the decreased molecular weight and lower content of total or reducing sugars after fermentation under anaerobic conditions. It was found that pH in the fermentation system decreased, and the production of short-chain fatty acids was significantly enhanced. Furthermore, in vitro fermentation of TFPS altered the composition of gut microbiota, specifically in elevating the ratio of Bacteroidetes to Firmicutes and enriching Prevotella. The present results suggest that TFPS has the potential to be developed as functional foods to modify gut microbiota.

Gut Microbiota Dysbiosis in Postweaning Piglets: Understanding the Keys to Health

Weaning is a critical event in the pig's life cycle, frequently associated with severe enteric infections and overuse of antibiotics; this raises serious economic and public health concerns. In this review, we explain why gut microbiota dysbiosis, induced by abrupt changes in the diet and environment of piglets, emerges as a leading cause of post-weaning diarrhea, even if the exact underlying mechanisms remain unclear. Then, we focus on nonantimicrobial alternatives, such as zinc oxide, essential oils, and prebiotics or probiotics, which are currently evaluated to restore intestinal balance and allow a better management of the crucial weaning transition. Finally, we discuss how in vitro models of the piglet gut could be advantageously used as a complement to ex vivo and in vivo studies for the development and testing of new feed additives.

Gum odina: an emerging gut modulating approach in colorectal cancer prevention

This study is focused on Gum Odina (GO), a reported prebiotic in our earlier work, and its impact on colorectal cancer (CRC).

In vitro fermentation of mulberry fruit polysaccharides by human fecal inocula and impact on microbiota

This study investigated thein vitrofermentation of polysaccharides fromMorus albaL., the contribution of its carbohydrates to the fermentation, and the effect on the composition of gut microbiota.

Prebiotic potential of gum odina and its impact on gut ecology: in vitro and in vivo assessments

The attributed effects of gum odina as a novel prebiotic and immunomodulatory agent are studied.

In vitro fermentation of prebiotic carbohydrates by intestinal microbiota in the presence of Lactobacillus amylovorus DSM 16998

The aim of this study was to evaluate the assimilation of the prebiotics fructooligosaccharides (FOS), galactooligosaccharides (GOS), and Konjac glucomannan oligosaccharides (KGMO) by three human (H1, H2 and H3) and pig (P1, P2 and P3) faecal microbiotas in the presence of the potentially probiotic strain Lactobacillus amylovorus DSM 16698, using an in vitro batch fermentation model. Total bacteria and L. amylovorus populations were quantified using qPCR and biochemical features (pH, production of short chain fatty acids (SCFA), lactate, ammonia, and carbohydrate assimilation) were determined. L. amylovorus did not have a competitive advantage under in vitro conditions, reflected by its reduced relative abundance during fermentation despite the carbohydrate sources added. Pig microbiota sustained more stable probiotic counts. Intermittently produced lactate was possibly assimilated by the microbiota and converted to other SCFA as the carbohydrates were assimilated, with H3 probably having a methanogenic metabolism with high lactate and acetate consumption except in the presence of FOS, which assimilation resulted in the highest total SCFA for this volunteer. Addition of FOS also resulted in lower pH and ammonia, which might have been used as nitrogen source by pig microbiota. KGMO needed longer fermentation periods to be completely assimilated by both human and porcine faecal microbiotas. Overall, our results reinforce the notion that care must be taken when generalising the effects claimed for a given probiotic or potentially probiotic strain, including the combination with different prebiotic substrates, since they may vary considerably among individuals, which is important when studying potentially pro- and prebiotic combinations for application as functional foods and feed ingredients.

Dietary flaxseed modulates the colonic microenvironment in healthy C57Bl/6 male mice which may alter susceptibility to gut-associated diseases

Understanding how dietary components alter the healthy baseline colonic microenvironment is important in determining their roles in influencing gut health and gut-associated diseases. Dietary flaxseed (FS) has demonstrated anti-colon cancer effects in numerous rodent models, however, exacerbated acute colonic mucosal injury and inflammation in a colitis model. This study investigates whether FS alters critical aspects of gut health in healthy unchallenged mice, which may help explain some of the divergent effects observed following different gut-associated disease challenges. Four-week-old C57Bl/6 male mice were fed an AIN-93G basal diet (BD) or an isocaloric BD+10% ground FS diet for 3 weeks. FS enhanced colon goblet cell density, mucus production, MUC2 mRNA expression, and cecal short chain fatty acid levels, indicative of beneficial intestinal barrier integrity responses. Additionally, FS enhanced colonic regenerating islet-derived protein 3 gamma (RegIIIγ) and reduced MUC1 and resistin-like molecule beta (RELMβ) mRNA expression which may indicate altered responses in regulating microbial defense and injury repair responses. FS diet altered the fecal microbial community structure (16S rRNA gene profiling), including a 20-fold increase in Prevotella spp. and a 30-fold reduction in Akkermansia muciniphila abundance. A 10-fold reduction in A. muciniphila abundance by FS was also demonstrated in the colon tissue-associated microbiota (quantitative PCR). Furthermore, fecal branched chain fatty acids were increased by FS, indicative of increased microbial-derived putrefactive compounds. In conclusion, consumption of a FS-supplemented diet alters the baseline colonic microenvironment of healthy mice which may modify subsequent mucosal microbial defense and injury-repair responses leading to altered susceptibility to different gut-associated diseases.

Adaptation of faecal microbiota in sows after diet changes and consequences for in vitro fermentation capacity

In vitro gas production studies are routinely used to assess the metabolic capacity of intestinal microbiota to ferment dietary fibre sources. The faecal inocula used during the in vitro gas production procedure are most often obtained from animals adapted to a certain diet. The present study was designed to assess whether 19 days of adaptation to a diet are sufficient for faecal inocula of pigs to reach a stable microbial composition and activity as determined by in vitro gas production. Eighteen multiparous sows were allotted to one of two treatments for three weeks: a diet high in fibre (H) or a diet low in fibre (L). After this 3-week period, the H group was transferred to the low fibre diet (HL-treatment) while the L group was transferred to the diet high in fibre (LH-treatment). Faecal samples were collected from each sow at 1, 4, 7, 10, 13, 16 and 19 days after the diet change and prepared as inoculum used for incubation with three contrasting fermentable substrates: oligofructose, soya pectin and cellulose. In addition, inocula were characterised using a phylogenetic microarray targeting the pig gastrointestinal tract microbiota. Time after diet change had an effect (P<0.05) on total gas production for the medium-fast fermentable substrates; soya pectin and oligofructose. For the more slowly fermentable cellulose, all measured fermentation parameters were consistently higher (P<0.05) for animals in the HL-treatment. Diet changes led to significant changes in relative abundance of specific bacteria, especially for members of the Bacteroidetes and Bacilli, which, respectively, increased or decreased for the LH-treatment, while changes were opposite for the HL-treatment. Changing the diet of sows led to changes in fermentation activity of the faecal microbiota and in composition of the microbiota over time. Adaptation of the microbiota as assessed by gas production occurred faster for LH-animals for fast fermentable substrates compared with HL-animals. Overall, adaptation of the large intestinal microbiota of sows as a result of ingestion of low and high fibre diets seems to take longer than 19 days, especially for the ability to ferment slowly fermentable substrates.

Temporal analysis of the effect of extruded flaxseed on the swine gut microbiota

Flaxseed is a rich source of α-linolenic acid, an essential ω-3 fatty acid reported to have beneficial health effects in humans. Feeding swine a diet supplemented with flaxseed has been found to enrich pork products with ω-3 fatty acids. However, the effect of flaxseed supplementation on the swine gut microbiota has not been assessed to date. The purpose of this study was to investigate if extruded flaxseed has any impact on the bacterial and archaeal microbiota in the feces of growing–finishing pigs over a 51-day period, using denaturing gradient gel electrophoresis (DGGE) and real-time PCR. Bacterial DGGE profile analysis revealed major temporal shifts in the bacterial microbiota with only minor ones related to diet. The archaeal microbiota was significantly less diverse than that of Bacteria. The majority of bacterial DGGE bands sequenced belonged to the Firmicutes phylum while the archaeal DGGE bands were found to consist of only 2 species, Methanobrevibacter smithii and Methanosphaera stadtmanae. The abundance of Bacteroidetes decreased significantly from day 0 to day 21 in all diet groups while the abundance of Firmicutes was relatively stable across all diet cohorts and sampling times. There was also no significant correlation between pig mass and the ratio of Firmicutes to Bacteroidetes. While the addition of extruded flaxseed to the feed of growing–finishing pigs was beneficial for improving ω-3 fatty acid content of pork, it had no detectable impact on the fecal bacterial and archaeal microbiota, suggesting that extruded flaxseed may be used to improve meat quality without adverse effect on the swine gut microbiota or animal performance.

Impact of whole grains on the gut microbiota: the next frontier for oats?

The gut microbiota plays important roles in proper gut function and can contribute to or help prevent disease. Whole grains, including oats, constitute important sources of nutrients for the gut microbiota and contribute to a healthy gut microbiome. In particular, whole grains provide NSP and resistant starch, unsaturated TAG and complex lipids, and phenolics. The composition of these constituents is unique in oats compared with other whole grains. Therefore, oats may contribute distinctive effects on gut health relative to other grains. Studies designed to determine these effects may uncover new human-health benefits of oat consumption.

Dietary flaxseed intake exacerbates acute colonic mucosal injury and inflammation induced by dextran sodium sulfate

Flaxseed (FS), a dietary oilseed, contains a variety of anti-inflammatory bioactives, including fermentable fiber, phenolic compounds (lignans), and the n-3 polyunsaturated fatty acid (PUFA) α-linolenic acid. The objective of this study was to determine the effects of FS and its n-3 PUFA-rich kernel or lignan- and soluble fiber-rich hull on colitis severity in a mouse model of acute colonic inflammation. C57BL/6 male mice were fed a basal diet (negative control) or a basal diet supplemented with 10% FS, 6% kernel, or 4% hull for 3 wk prior to and during colitis induction via 5 days of 2% (wt/vol) dextran sodium sulfate (DSS) in their drinking water (n = 12/group). An increase in anti-inflammatory metabolites (hepatic n-3 PUFAs, serum mammalian lignans, and cecal short-chain fatty acids) was associated with consumption of all FS-based diets, but not with anti-inflammatory effects in DSS-exposed mice. Dietary FS exacerbated DSS-induced acute colitis, as indicated by a heightened disease activity index and an increase in colonic injury and inflammatory biomarkers [histological damage, apoptosis, myeloperoxidase, inflammatory cytokines (IL-6 and IL-1β), and NF-κB signaling-related genes (Nfkb1, Ccl5, Bcl2a1a, Egfr, Relb, Birc3, and Atf1)]. Additionally, the adverse effect of the FS diet was extended systemically, as serum cytokines (IL-6, IFNγ, and IL-1β) and hepatic cholesterol levels were increased. The adverse effects of FS were not associated with alterations in fecal microbial load or systemic bacterial translocation (endotoxemia). Collectively, this study demonstrates that although consumption of a 10% FS diet enhanced the levels of n-3 PUFAs, short-chain polyunsaturated fatty acids, and lignans in mice, it exacerbated DSS-induced colonic injury and inflammation.

In vitro continuous fermentation model (PolyFermS) of the swine proximal colon for simultaneous testing on the same gut microbiota

In vitro gut modeling provides a useful platform for a fast and reproducible assessment of treatment-related changes. Currently, pig intestinal fermentation models are mainly batch models with important inherent limitations. In this study we developed a novel in vitro continuous fermentation model, mimicking the porcine proximal colon, which we validated during 54 days of fermentation. This model, based on our recent PolyFermS design, allows comparing different treatment effects on the same microbiota. It is composed of a first-stage inoculum reactor seeded with immobilized fecal swine microbiota and used to constantly inoculate (10% v/v) five second-stage reactors, with all reactors fed with fresh nutritive chyme medium and set to mimic the swine proximal colon. Reactor effluents were analyzed for metabolite concentrations and bacterial composition by HPLC and quantitative PCR, and microbial diversity was assessed by 454 pyrosequencing. The novel PolyFermS featured stable microbial composition, diversity and metabolite production, consistent with bacterial activity reported for swine proximal colon in vivo. The constant inoculation provided by the inoculum reactor generated reproducible microbial ecosystems in all second-stage reactors, allowing the simultaneous investigation and direct comparison of different treatments on the same porcine gut microbiota. Our data demonstrate the unique features of this novel PolyFermS design for the swine proximal colon. The model provides a tool for efficient, reproducible and cost-effective screening of environmental factors, such as dietary additives, on pig colonic fermentation.

Dietary fibre affects intestinal mucosal barrier function and regulates intestinal bacteria in weaning piglets

The objective of the present study was to evaluate the effects of fibre source on intestinal mucosal barrier function in weaning piglets. A total of 125 piglets were randomly allotted on the basis of their body weight and litters to one of five experimental diets, i.e. a control diet without fibre source (CT), and diets in which expanded maize was replaced by 10% maize fibre (MF), 10% soyabean fibre (SF), 10% wheat bran fibre (WBF) or 10% pea fibre (PF). The diets and water were fed ad libitum for 30 d. Piglets on the WBF and PF diets had lower diarrhoea incidence compared with the MF- and SF-fed animals. A higher ratio of villous height:crypt depth in the ileum of WBF-fed piglets and higher colonic goblet cells in WBF- and PF-fed piglets were observed compared with CT-, MF- and SF-fed piglets. In the intestinal digesta, feeding WBF and PF resulted in increased Lactobacillus counts in the ileum and Bifidobacterium counts in the colon. Lower Escherichia coli counts occurred in the ileum and colon of WBF-fed piglets than in SF-fed piglets. Tight junction protein (zonula occludens 1; ZO-1) and Toll-like receptor 2 (TLR2) gene mRNA levels were up-regulated in the ileum and colon of pigs fed WBF; however, feeding MF and SF raised IL-1α and TNF-α mRNA levels. Furthermore, higher diamine oxidase activities, transforming growth factor-α, trefoil factor family and MHC-II concentration occurred when feeding WBF and PF. In conclusion, the various fibre sources had different effects on the ileal and colonic barrier function. Clearly, WBF and PF improved the intestinal barrier function, probably mediated by changes in microbiota composition and concomitant changes in TLR2 gene expression.

Fecal microbial communities of healthy adult dogs fed raw meat-based diets with or without inulin or yeast cell wall extracts as assessed by 454 pyrosequencing

Our objective was to determine the effects of feeding raw meat-based diets with or without inulin or yeast cell wall extract (YCW) on fecal microbial communities of dogs using 454 pyrosequencing. Six healthy female adult beagles (5.5 ± 0.5 years; 8.5 ± 0.5 kg) were randomly assigned to six test diets using a Latin square design: (1) beef control; (2) beef + 1.4% inulin; (3) beef + 1.4% YCW; (4) chicken control; (5) chicken + 1.4% inulin; and (6) chicken + 1.4% YCW. Following 14 days of adaptation, fresh fecal samples were collected on day 15 or day 16 of each period. Fecal genomic DNA was extracted and used to create 16S rRNA gene amplicons, which were subjected to 454 pyrosequencing and qPCR. Predominant fecal bacterial phyla included Fusobacteria, Firmicutes, Bacteroidetes, and Proteobacteria. Beef-based diets increased (P < 0.05) Escherichia, but decreased (P < 0.05) Anaerobiospirillum vs. chicken-based diets. Inulin decreased (P < 0.05) Enterobacteriaceae. Inulin increased (P < 0.05) Megamonas vs. control. Inulin also decreased (P < 0.05) Escherichia vs. YCW. qPCR data showed that YCW increased (P < 0.05) Bifidobacterium vs. inulin and control and inulin increased (P < 0.05) Lactobacillus vs. YCW. Although a few changes in fecal microbiota were observed with inulin or YCW consumption, a strong prebiotic effect was not observed.

Linking microbial community structure to function in representative simulated systems

Pathogenic bacteria are generally studied as a single strain under ideal growing conditions, although these conditions are not the norm in the environments in which pathogens typically proliferate. In this investigation, a representative microbial community along with Escherichia coli O157:H7, a model pathogen, was studied in three environments in which such a pathogen could be found: a human colon, a septic tank, and groundwater. Each of these systems was built in the lab in order to retain the physical/chemical and microbial complexity of the environments while maintaining control of the feed into the models. The microbial community in the colon was found to have a high percentage of bacteriodetes and firmicutes, while the septic tank and groundwater systems were composed mostly of proteobacteria. The introduction of E. coli O157:H7 into the simulated systems elicited a shift in the structures and phenotypic cell characteristics of the microbial communities. The fate and transport of the microbial community with E. coli O157:H7 were found to be significantly different from those of E. coli O157:H7 studied as a single isolate, suggesting that the behavior of the organism in the environment was different from that previously conceived. The findings in this study clearly suggest that to gain insight into the fate of pathogens, cells should be grown and analyzed under conditions simulating those of the environment in which the pathogens are present.

Effect of galactooligosaccharides and Bifidobacterium animalis Bb-12 on growth of Lactobacillus amylovorus DSM 16698, microbial community structure, and metabolite production in an in vitro colonic model set up with human or pig microbiota

A validated in vitro model of the large intestine (TIM-2), set up with human or pig faeces, was used to evaluate the impact of potentially probiotic Lactobacillus amylovorus DSM 16698, administered alone (i), in the presence of prebiotic galactooligosaccharides (GOS) (ii), and co-administered with probiotic Bifidobacterium animalis ssp. lactis Bb-12 (Bb-12) (iii) on GOS degradation, microbial growth (L. amylovorus, lactobacilli, bifidobacteria and total bacteria) and metabolite production. High performance anion exchange chromatography revealed that GOS degradation was more pronounced in TIM-2 inoculated with pig faeces than with human faeces. Denaturing gradient gel electrophoresis profiling of PCR-amplified 16S rRNA genes detected a more complex Lactobacillus spp. community in pig faecal material than in human faecal inoculum. According to 16S rRNA gene-targeted qPCR, GOS stimulated the growth of lactobacilli and bifidobacteria in faecal material from both materials. The cumulative production of short chain fatty acids and ammonia was higher (P < 0.05) for pig than for human faeces. However, lactate accumulation was higher (P < 0.05) in the human model and increased after co-administration with GOS and Bb-12. This study reinforced the notion that differences in microbiota composition between target host organisms need to be considered when animal data are extrapolated to human, as is often done with pre- and probiotic intervention studies.

Polysaccharide from seeds of Plantago asiatica L. increases short-chain fatty acid production and fecal moisture along with lowering pH in mouse colon

Mice (20.0 ± 2.0 g, n = 48 per group) were given 30 days oral administration of polysaccharide from Plantago asiatica L. seeds at the dose of 0.4 g/kg body weight by gavage to investigate the effects of the polysaccharide on mouse colon. Results showed that the concentrations of total short-chain fatty acids (SCFA), acetic, propionic, and n-butyric acids in mouse colonic content of polysaccharide treated group were all significantly higher than that of control group (water) (p < 0.05). In addition, moisture of mouse colonic content of polysaccharide treated group was also notably higher than that of the control group (p < 0.05) indicating the intake of polysaccharide from P. asiatica L. resulted in a stronger water-holding capacity for colonic content throughout the experimental period. Furthermore, a decreased pH (from 7.5 ± 0.1 to 7.2 ± 0.1) was observed in mouse colon of the polysaccharide treated group compared with the control group (pH from 7.5 ± 0.1 to 7.5 ± 0.1). These results suggested that the intake of the polysaccharide from P. asiatica L. might be beneficial for the colon health.

Fenugreek seed affects intestinal microbiota and immunological variables in piglets after weaning

Fenugreek seed has been shown to affect the intestinal microbiota and immunological responses in animals. A feeding trial with male castrated piglets was performed over 28 d without or with the addition of 1·5 g fenugreek seeds/kg complete diet in ten and eleven piglets, weaned at 21 d. In the intestinal tract, pH, lactate and SCFA were measured as major bacterial metabolites. Immune cell phenotypes, phagocytic activity and lymphocyte proliferation after stimulation with pokeweed mitogen, concanavalin A and phytohaemagglutinin M were measured by flow cytometry. Health status and performance of the piglets were not affected by fenugreek. The pH in the caecum and colon were reduced compared with the control (P< 0·05). Higher concentrations of l-lactic acid were recorded in the small-intestinal digesta (average concentrations from the duodenum, jejunum and ileum; P< 0·05), while the concentrations of SCFA remained unchanged except an increase in n-butyric acid in colon contents (P< 0·05). The piglets fed the fenugreek diet had higher Lactobacillus and clostridium cluster I concentrations and lower Escherichia, Hafnia and Shigella concentrations in the small intestine. The addition of fenugreek increased the relative concentration of the γδ T-cell population (TCR1+CD8α-) in the blood with a simultaneous reduction of antigen-presenting cells (MHCII+CD5-) (P< 0·05). Proliferation rate and phagocytosis activity of monocytes were not affected by the additive. In conclusion, fenugreek seeds might be interesting as a feed ingredient for young piglets due to their effects on the intestinal microbiota and immunological variables. The impact on performance and animal health has to be further evaluated.