Effects of the different dietary fibers on luminal microbiota composition and mucosal gene expression in pig colons

Reduction of Redox Potential Exerts a Key Role in Modulating Gut Microbial Taxa and Function by Dietary Supplementation of Pectin in a Pig Model

Pectin exists in a vast range of plants and has a long history of acting as a functional food additive with potential prebiotic effects on intestinal health. However, knowledge of how pectin regulates gut microbial communities is still insufficient and limited. Here, metatranscriptome sequencing revealed that a pectin-enriched diet (PEC) decreased the abundances of fungal keystone taxa (e.g., amino acid-producing Kazachstania spp.) and their genes involved in oxidative phosphorylation, while it increased the abundance of sulfate-reducing Desulfovibrio spp., and methane-producing Methanobrevibacter spp. in colon microbiomes. Furthermore, we first confirmed that PEC decreased fecal redox potential in a fistula pig model, which could be supported by the enrichment of antioxidants (e.g., inosine) in feces. Fecal metagenome analysis disclosed that certain microbial taxa promoted inosine biosynthesis from pectin degradation, including Prevotella, which plays an essential role in pectin biodegradation. Overall, these results demonstrate that pectin decreases the redox potential in pig hindgut to modulate microbial composition and functions, and specific microorganisms generate reducing agents in the course of pectin degradation to decrease redox potential of microbial ecosystem. IMPORTANCE Collective studies indicate that pectin degradation promotes extensive microorganisms that can be involved in pectin degradation directly or indirectly, or benefit from the altered physiological conditions caused by pectin ingestions. Our study focuses on effects of pectin on gut microbial taxa and functions, as well as its interactions with altered environmental features. Our results demonstrate pectin-induced proreducing shifts on colon microbial taxa and functions, and first confirm that pectin decreases hindgut redox potential, which is an important environmental feature that can modulate microbial communities. These results infer that there is bidirectional regulation between microbiota and redox potential during pectin degradation. In general, this investigation proposes new insights into the pectin-modulating gut microbial ecosystem and also provides new perspectives for targeting modulation of gut microbiota.

Influence of spent ginger yeast cultures on the production performance, egg quality, serum composition, and intestinal microbiota of laying hens

Objective

Spent ginger is a byproduct of juice extraction from the rhizome of ginger (Zingiber officinale). Despite its nutritional value, it is difficult to preserve or further process and thus is often wasted. This study uses spent ginger as a substrate for fermentation and cultivates spent ginger yeast cultures (SGYCs) that are then added to the feed of laying hens. The effects of SGYCs on production performance, egg quality, serum composition, and intestinal microbiota of laying hens were investigated.

Methods

Eighty 60-week-old Hy-Line Brown hens were separated into 5 experimental groups with 4 replicates per group (4 hens per cage, 4 cages per replicate). The control group was fed a basal diet while experimental groups were also given SGYCs at the levels of 5, 10, 20, and 40 g/kg for 6 weeks.

Results

The addition of SGYCs significantly increased the laying rate and nutrient digestibility, decreased feed conversion ratio, and enhanced the color of egg yolks (p<0.05). No changes were observed in activity levels of alanine aminotransferase and aspartate aminotransferase in the serum (p>0.05), but the activities of superoxide dismutase, glutathione peroxidase, and peroxidase all significantly increased, and contents of malondialdehyde were significantly reduced (p<0.05). In addition, changes in the relative abundance of Firmicutes and Bacteroidetes might be the main factor contributing to the significant increase in the apparent digestibility of crude protein and crude fat in laying hens (p<0.05).

Conclusion

The current evidence shows that dietary supplementation of SGYCs to the feed of laying hens can improve laying rates, enhance antioxidative defenses, and influence dominant intestinal bacteria.

Microbiomes in the Intestine of Developing Pigs: Implications for Nutrition and Health

The past decade has seen an expansion of studies on the role of gut microbiome in piglet nutrition and health. With the help of culture-independent sequencing techniques, the colonization of gut microbiota and their implication in physiology are being investigated in depth. Immediately after birth, the microbes begin to colonize following an age-dependent trajectory, which can be modified by maternal environment, diet, antibiotics, and fecal microbiota transplantation. The early-life gut microbiome is relatively simple but enriched with huge metabolic potential to utilize milk oligosaccharides and affect the epithelial function. After weaning, the gut microbiome develops towards a gradual adaptation to the introduction of solid food, with an enhanced ability to metabolize amino acids, fibers, and bile acids. Here we summarize the compositional and functional difference of the gut microbiome in the keystone developing phases, with a specific focus on the use of different nutritional approaches based on the phase-specific gut microbiome.

Metatranscriptomic analysis of colonic microbiota's functional response to different dietary fibers in growing pigs

Background

Dietary fibers are widely considered to be beneficial to health as they produce nutrients through gut microbial fermentation while facilitating weight management and boosting gut health. To date, the gene expression profiles of the carbohydrate active enzymes (CAZymes) that respond to different types of fibers (raw potato starch, RPS; inulin, INU; pectin, PEC) in the gut microbes of pigs are not well understood. Therefore, we investigated the functional response of colonic microbiota to different dietary fibers in pigs through metatranscriptomic analysis.

Results

The results showed that the microbial composition and CAZyme structure of the three experimental groups changed significantly compared with the control group (CON). Based on a comparative analysis with the control diet, RPS increased the abundance of Parabacteroides, Ruminococcus, Faecalibacterium and Alloprevotella but decreased Sutterella; INU increased the relative abundance of Fusobacterium and Rhodococcus but decreased Bacillus; and PEC increased the relative abundance of the Streptococcus and Bacteroidetes groups but decreased Clostridium, Clostridioides, Intestinibacter, Gemmiger, Muribaculum and Vibrio. The gene expression of CAZymes GH8, GH14, GH24, GH38, GT14, GT31, GT77 and GT91 downregulated but that of GH77, GH97, GT3, GT10 and GT27 upregulated in the RPS diet group; the gene expression of AA4, AA7, GH14, GH15, GH24, GH26, GH27, GH38, GH101, GT26, GT27 and GT38 downregulated in the INU group; and the gene expression of PL4, AA1, GT32, GH18, GH37, GH101 and GH112 downregulated but that of CE14, AA3, AA12, GH5, GH102 and GH103 upregulated in the PEC group. Compared with the RPS and INU groups, the composition of colonic microbiota in the PEC group exhibited more diverse changes with the variation of CAZymes and Streptococcus as the main contributor to CBM61, which greatly promoted the digestion of pectin.

Conclusion

The results of this exploratory study provided a comprehensive overview of the effects of different fibers on nutrient digestibility, gut microbiota and CAZymes in pig colon, which will furnish new insights into the impacts of the use of dietary fibers on animal and human health.

Supplementary Information

The online version contains supplementary material available at 10.1186/s42523-021-00108-1.

Preparation and characterization of native and autoclaving-cooling treated Pinellia ternate starch and its impact on gut microbiota

The aim of this study was to investigate and compare the structural and physicochemical properties of native Banxia starch (BXS) and autoclaving-cooling treated Banxia starch (CTBXS) and its related impacts on production of short chain fatty acids (SCFAs) and human gut microbiota by in vitro fecal fermentation. BXS had semicircle to spherical granules, whereas CTBXS exhibited block-shape. According to XRD and TGA, BXS had a C-type crystalline pattern, while CTBXS had a B-type crystalline pattern. CTBXS had better thermal stability than BXS. In addition, BXS exhibited significantly higher solubility and swelling power than CTBXS, and CTBXS had higher content of SDS than BXS. Moreover, BXS and CTBXS could change the composition and abundance of gut microbiota, could also promote the production of SCFAs. This study is beneficial to well understand the in vitro digestion and fecal fermentation behaviors of BXS and CTBXS, and can be developed as a potential functional food with the aim of improving colonic health.

Swine gut microbiota and its interaction with host nutrient metabolism

Gut microbiota is generally recognized to play a crucial role in maintaining host health and metabolism. The correlation among gut microbiota, glycolipid metabolism, and metabolic diseases has been well reviewed in humans. However, the interplay between gut microbiota and host metabolism in swine remains incompletely understood. Given the limitation in conducting human experiments and the high similarity between swine and humans in terms of anatomy, physiology, polyphagy, habits, and metabolism and in terms of the composition of gut microbiota, there is a pressing need to summarize the knowledge gained regarding swine gut microbiota, its interplay with host metabolism, and the underlying mechanisms. This review aimed to outline the bidirectional regulation between gut microbiota and nutrient metabolism in swine and to emphasize the action mechanisms underlying the complex microbiome-host crosstalk via the gut microbiota-gut-brain axis. Moreover, it highlights the new advances in knowledge of the diurnal rhythmicity of gut microbiota. A better understanding of these aspects can not only shed light on healthy and efficient pork production but also promote our knowledge on the associations between gut microbiota and the microbiome-host crosstalk mechanism. More importantly, knowledge on microbiota, host health and metabolism facilitates the development of a precise intervention therapy targeting the gut microbiota.

Effect of Broussonetia papyrifera silage on the serum indicators, hindgut parameters and fecal bacterial community of Holstein heifers

This study investigated the effects of substitution of whole corn silage (WCS) with Broussonetia papyrifera silage (BPS) in different ratios on the serum indicators, hindgut fermentation parameters (pH, ammoniacal nitrogen, and volatile fatty acids), and fecal bacterial community of Holstein heifers. Sixteen heifers (8-month-old, 220 ± 30 kg) were randomly divided into four treatments according to different BPS substitution ratios of feed basis (0%, 25%, 50%, and 75%). The experiment consisted of a 7-day preliminary feeding period and a 30-day experimental period. On the last day of the trial, the blood samples were collected from caudal vein, and the feces samples were collected from rectum. With the increasing of BPS content, the concentration of malondialdehyde (MDA) and interleukin-1β (IL-1β) in serum decreased (P < 0.05), and the immunoglobulin A (IgA) and IL-4 content of serum increased (P < 0.05); and the hindgut pH value increased (P < 0.05). 16S rRNA sequencing found that the dominant phyla were Firmicutes, Bacteroidetes, and Verrucomicrobia; and the dominant genera were Ruminococcaceae_UCG-005, Ruminococcaceae_UCG-010, and Rikenellaceae_RC9_gut_group. Linear Discriminant Analysis Effect Size (LEfSe) analysis found 12 differential operational taxonomic units (OTUs) which have strong correlation with some serum and hindgut indicators, and have the potential to be used as biomarkers. Phylogenetic Investigation of Communities by Reconstruction of Unobserved States (PICRUSt) found that BPS have impacts on the pathways, such as carbohydrate transport and metabolism, and promotes amino acid transport and metabolism. To sum up, inclusion of BPS in heifer diets can affect serum anti-oxidant and immune indicators, fecal parameters, composition and function of fecal microorganisms in Holstein heifers.

Inulin improves the egg production performance and affects the cecum microbiota of laying hens

Egg production performance, egg quality, nutrient digestibility, and microbial composition as affected by dietary inulin supplementation were evaluated in laying hens. A total of 300 laying hens were divided into 5 groups and fed diets containing inulin at levels of 0 (control), 5, 10, 15 and 20 g/kg, respectively. The results showed that the 15 g/kg inulin supplementation level improved average egg weight by 2.54%, egg mass by 5.76%, and laying rate by 3.09%, and decreased the feed conversion ratio by 3.61% compared to those of the control during feeding weeks 1 to 8. Dietary inulin supplementation improved eggshell thickness, nutrient digestibility and cecum Bacteroidales_S24-7_ group abundance in the laying hens. In conclusion, dietary inulin supplementation, particularly at the level of 15 g/kg, improved the egg production performance and eggshell thickness of laying hens, mainly due to increased nutrient digestibility and selective modulations of the cecum microbial communities.

Host-Microbiota Interactions in Ileum and Caecum of Pigs Divergent in Feed Efficiency Contribute to Nutrient Utilization

The composition of the intestinal microbiota plays an important role in the digestion and utilization of nutrients and for gut health. Low-fiber diets stimulate digestion and absorption processes, predominantly in the upper region of the gastrointestinal tract, thereby increasing the conversion of feed into body weight. As a consequence, the chemical composition of digesta after duodenal and jejunal absorption processes and passage has a limited complexity affecting colonization and molecular profiles of enterocytes in the hind gut. To decipher ileal and caecal microbial ecosystems and host transcriptional profiles that are beneficial for effective use of the remaining nutrients, pigs differing in feeding efficiency were studied. Biological functions that were consistently enriched at both the gene and microbiota levels comprise immunity-related processes, which ensure the integrity of the gastrointestinal tract. In addition, the differential abundance of certain genera, including Rothia, Subdoligranulu, Leeia and Cellulosilyticum, reflects the establishment of a microbial profile that supports the digestion of endogenously indigestible dietary components in highly feed-efficient pigs. Overall, the results indicate the potential to promote these beneficial functions and further improve feed efficiency through manipulation of dietary and probiotic strategies.

Modulation of Pectin on Mucosal Innate Immune Function in Pigs Mediated by Gut Microbiota

The use of prebiotics to regulate gut microbiota is a promising strategy to improve gut health. Pectin (PEC) is a prebiotic carbohydrate that enhances the health of the gut by promoting the growth of beneficial microbes. These microbes produce metabolites that are known to improve mucosal immune responses. This study was conducted to better understand effects of PEC on the microbiome and mucosal immunity in pigs. Pigs were fed two diets, with or without 5% apple PEC, for 72 days. Effects of PEC on the microbiota, cytokine expression, short-chain fatty acids (SCFAs) concentration and barrier function were examined in the ileum and cecum of the pigs. An integrative analysis was used to determine interactions of PEC consumption with bacterial metabolites and microbiome composition and host mucosal responses. Consumption of PEC reduced expression of pro-inflammatory cytokines such as IFN-γ, IL-6, IL-8, IL-12 and IL-18, and the activation of the pro-inflammatory NF-κB signaling cascade. Expression of MUC2 and TFF and the sIgA content was upregulated in the mucosa of PEC-fed pigs. Network analysis revealed that PEC induced significant interactions between microbiome composition in the ileum and cecum on mucosal immune pathways. PEC-induced changes in bacterial genera and fermentation metabolites, such as Akkermansia, Faecalibacterium, Oscillibacter, Lawsonia and butyrate, correlated with the differentially expressed genes and cytokines in the mucosa. In summary, the results demonstrate the anti-inflammatory properties of PEC on mucosal immune status in the ileum and cecum effected through modulation of the host microbiome.

Effect of lotus seed resistant starch on tolerance of mice fecal microbiota to bile salt

We investigated the effect of lotus seed resistant starch (LRS) on mice fecal microbiota tolerance to bile salt by culturing organisms compared to inulin (INU) glucose (GLU) and waxy corn starch (WAX). Operational taxonomic units (OTUs) and diversity indices in LRS and INU groups were increased in the presence of 0.03% to 0.3% bile salt, while they were decreased in GLU, and OTUs were decreased in WAX. Specifically, LRS promoted proliferation of Lactobacillus, which potentially used bile acid, and inhibited growth of the potentially harmful bacteria Enterococcus and Staphylococcus. Moreover, Lactobacillus was negatively correlated with Salinicoccus and Granulicatella in GLU, LRS and INU groups at 1.5% bile salt. With LRS, amino acid metabolic pathways were increased while pathogens causing certain diseases were decreased. LRS increased the tolerance of mice fecal microbiota to bile salt by promoting the proliferation of bacteria utilizing bile acid and inhibiting the growth of harmful bacteria.