Exogenous Butyrate Research Articles

Butyrate: a bridge between intestinal flora and rheumatoid arthritis.

In patients with rheumatoid arthritis (RA), intestinal flora imbalance and butyrate metabolism disorders precede clinical arthritis and are associated with the pathogenesis of RA. This imbalance can alter the immunology and intestinal permeability of the intestinal mucosa, leading to damage to the intestinal barrier. In this context, bacteria and their metabolites can enter the bloodstream and reach the distant target tissues of the host, resulting in local inflammation and aggravating arthritis. Additionally, arthritis is also exacerbated by bone destruction and immune tolerance due to disturbed differentiation of osteoclasts and adaptive immune cells. Of note, butyrate is a metabolite of intestinal flora, which not only locally inhibits intestinal immunity and targets zonulin and tight junction proteins to alleviate intestinal barrier-mediated arthritis but also inhibits osteoclasts and autoantibodies and balances the immune responses of T and B lymphocytes throughout the body to repress bone erosion and inflammation. Therefore, butyrate is a key intermediate linking intestinal flora to the host. As a result, restoring the butyrate-producing capacity of intestinal flora and using exogenous butyrate are potential therapeutic strategies for RA in the future.

Butyrate protects the intestinal barrier by upregulating Fut2 expression via MEK4-JNK signaling pathway activation.

Necrotizing enterocolitis (NEC) is a severe gastrointestinal inflammatory disease in neonates. Fucosyltransferase 2 (Fut2) regulates intestinal epithelial cell fucosylation. In this study, we aimed to investigate butyrate-mediated upregulation of Fut2 expression and the underlying mechanisms. In vivo and in vitro models were established. SP600125 was used to inhibit the MEK4-JNK pathway, and anisomycin was used to activate the MEK4-JNK pathway. Fut2, occludin, and ZO-1 expressions were assessed. Furthermore, intestinal permeability was analyzed by FITC-Dextran. The expression of proteins in the MEK-4-JNK pathway was examined by western blotting. In vivo, the addition of exogenous butyrate notably upregulated Fut2, occludin, and ZO-1 expressions and reduced intestinal permeability in mice with NEC. Butyrate may increase the phosphorylation of MEK4, JNK, and c-jun, which are key components of the MEK4-JNK pathway. Additionally, SP600125 inhibited their phosphorylation, which was reversed by anisomycin treatment. In vitro, butyrate substantially increased occludin and ZO-1 expressions. Butyrate considerably increased Fut2 expression and markedly upregulated p-MEK4, p-JNK, and p-c-jun expressions. SP600125 administration decreased their expressions, while anisomycin administration increased their expressions. Butyrate upregulated Fut2 expression via activation of the MEK4-JNK pathway, improved intestinal barrier integrity, and protected neonatal mice from NEC. We found that exogenous butyrate could improve intestinal barrier integrity and protect against NEC in neonatal mice. Our data showed that exogenous butyrate supplementation upregulated Fut2 expression by activating the MEK4-JNK pathway. Our study provides novel insights into the pathogenesis of NEC, thereby laying an experimental foundation for future clinical research on the use of butyrate in NEC treatment.

Exogenous butyrate inhibits butyrogenic metabolism and alters virulence phenotypes in Clostridioides difficile.

The gut microbiome engenders colonization resistance against the diarrheal pathogen Clostridioides difficile, but the molecular basis of this colonization resistance is incompletely understood. A prominent class of gut microbiome-produced metabolites important for colonization resistance against C. difficile is short-chain fatty acids (SCFAs). In particular, one SCFA (butyrate) decreases the fitness of C. difficile in vitro and is correlated with C. difficile-inhospitable gut environments, both in mice and in humans. Here, we demonstrate that butyrate-dependent growth inhibition in C. difficile occurs under conditions where C. difficile also produces butyrate as a metabolic end product. Furthermore, we show that exogenous butyrate is internalized into C. difficile cells and is incorporated into intracellular CoA pools where it is metabolized in a reverse (energetically unfavorable) direction to crotonyl-CoA and (S)-3-hydroxybutyryl-CoA and/or 4-hydroxybutyryl-CoA. This internalization of butyrate and reverse metabolic flow of a butyrogenic pathway(s) in C. difficile coincides with alterations in toxin release and sporulation. Together, this work highlights butyrate as a marker of a C. difficile-inhospitable environment to which C. difficile responds by releasing its diarrheagenic toxins and producing environmentally resistant spores necessary for transmission between hosts. These findings provide foundational data for understanding the molecular and genetic basis of how C. difficile growth is inhibited by butyrate and how butyrate alters C. difficile virulence in the face of a highly competitive and dynamic gut environment.IMPORTANCEThe gut microbiome engenders colonization resistance against the diarrheal pathogen Clostridioides difficile, but the molecular basis of this colonization resistance is incompletely understood, which hinders the development of novel therapeutic interventions for C. difficile infection (CDI). We investigated how C. difficile responds to butyrate, an end-product of gut microbiome community metabolism which inhibits C. difficile growth. We show that exogenously produced butyrate is internalized into C. difficile, which inhibits C. difficile growth by interfering with its own butyrate production. This growth inhibition coincides with increased toxin release from C. difficile cells and the production of environmentally resistant spores necessary for transmission between hosts. Future work to disentangle the molecular mechanisms underlying these growth and virulence phenotypes will likely lead to new strategies to restrict C. difficile growth in the gut and minimize its pathogenesis during CDI.

DOP39 Constructing butyrate-producing yeast as a cell-dependent treatment option for Inflammatory Bowel Disease

Abstract Background Intestinal microbiota dysbiosis and metabolic disruption are essential characteristics of inflammatory bowel disorders (IBD). Butyrate has been proven to regulate immune response and gut microbiota. It has been confirmed that the butyrate content in the intestinal cavity of IBD patients decreases (Fig. 1A). Methods In this study, gene editing was used to reconstruct the butyrate synthesis pathway and regulate related metabolic pathways in Saccharomyces cerevisiae to produce butyrate and enrich its synthesis in anaerobic environments to cope with complex intestinal conditions. A series of engineered strains were co-cultured with gut microbiota samples from six patients with mild-to-moderate ulcerative colitis and 16S ribosomal RNA sequencing was used to analyze the regulatory effect of engineered strains on intestinal microbiota in vitro. The TNBS-induced IBD mice model was used to explore the protective effect of butyrate-engineered yeasts in vivo. Results A series of engineered strains with different butyrate synthesis abilities was constructed to meet the needs of different patients. S. cerevisiae was engineered by introducing an exogenous butyrate synthesis pathway and regulating yeast metabolism to increase the availability of the precursors. Engineered yeast can produce up to 1.8 g/L butyrate (Fig. 1B). The modification of related metabolic pathways also focused on enhancing the synthesis of butyrate under anaerobic conditions to enable engineered yeasts to adapt to the intestinal environment. This series of engineered yeasts with different butyrate synthesis abilities regulated the intestinal microbiota of IBD patients to varying degrees, enhancing the abundance of related probiotics such as Lactobacillus and Bifidobacterium and reducing the abundance of harmful bacteria like Candidatus Bacilloplasma (Fig. 1C). Meanwhile, strains improved TNBS-induced colitis in mice by restoring butyrate content. Remarkably, the engineered strain with the second-highest butyrate yield showed the most significant therapeutic effect (Fig. 1D). Conclusion This study realized butyrate synthesis in S. cerevisiae and regulated related metabolic modules to adjust the butyrate production to achieve the best therapeutic effect on colitis in vivo and in vitro. In addition, the strain with the second-highest butyrate production has the best therapeutic effect. This highlights the dual role of butyrate in epithelial cell repair and suggests a therapeutic window for IBD treatment through butyrate supplementation. Selecting the most suitable strain for each patient's condition is essential for restoring butyrate levels, regulating microbiota, and promoting mucosal repair.

Butyrate supplementation reduces sarcopenia by repairing neuromuscular junction in patients with chronic obstructive pulmonary disease

IntroductionChronic obstructive pulmonary disease (COPD) is associated with an intestinal leak and neuromuscular junction (NMJ) degradation, which contributes to physical compromise and accelerated age-related muscle loss, called sarcopenia. However, the relevant interventions partly remain ineffective. We investigated the effects of exogenous butyrate on sarcopenia and physical capacity with relevance to intestinal permeability and NMJ integrity in COPD patients. MethodsCOPD patients were randomized into placebo (n = 67) and butyrate (n = 64) groups in a double-blind manner. The patients in the butyrate group received one 300 mg capsule a day for 12 weeks. We measured circulating markers of intestinal leak (zonulin), systemic bacterial load (LBP), and NMJ loss (CAF22), along with handgrip strength (HGS), and short physical performance battery (SPPB) at baseline and 12 weeks. ResultsButyrate supplementation improved HGS and gait speed in COPD patients. Among SPPB indices, butyrate improved the ability to maintain postural balance and walking and prevented a decline in the ability to rise from a chair. Butyrate also reduced the plasma levels of zonulin, LBP, and CAF22 levels in COPD patients (all p < 0.05). Regression analysis revealed significant associations of plasma zonulin and CAF22 with HGS, gait speed, and cumulative SPPB scores in butyrate group. These changes were associated with reduced markers of inflammation and muscle damage. ConclusionButyrate may provide a therapeutic approach to sarcopenia and physical dependency in COPD by repairing intestinal leak and NMJ loss.

ASTRAGALOSIDE Ⅳ MODULATES GUT MACROPHAGES M1/M2 POLARIZATION BY RESHAPING GUT MICROBIOTA AND SHORT CHAIN FATTY ACIDS IN SEPSIS.

M1 macrophage-mediated inflammation is critical in sepsis. We previously found the protective role of astragaloside intravenous (AS-IV) in sepsis-associated gut impairment, whose specific mechanism remains unknown. Gut microbiota modulates gut homeostatic balance to avoid excessive inflammation. Here, we aimed to investigate effects of AS-IV on gut macrophages polarization and potential roles of gut microbiota and short chain fatty acids (SCFAs) in septic gut damage. Mice were pretreated by AS-IV gavage for 7 days before cecal ligation and puncture. M1 polarization of gut lamina propria macrophages (LpMs) was promoted by cecal ligation and puncture, accompanied by abnormal cytokines release and intestinal barrier dysfunction. NLRP3 inflammasome was activated in M1 LpMs. 16S rRNA sequencing demonstrated gut microbiota imbalance. The levels of acetate, propionate, and butyrate in fecal samples decreased. Notably, AS-IV reversed LpMs M1/M2 polarization, lightened gut inflammation and barrier injury, reduced NLRP3 inflammasome expression in LpMs, restored the diversity of gut microbiome, and increased butyrate levels. Similarly, these benefits were mimicked by fecal microbiota transplantation or exogenous butyrate supplementation. In Caco-2 and THP-1 cocultured model, LPS and interferon γ caused THP-1 M1 polarization, Caco-2 barrier impairment, abnormal cytokines release, and high NLRP3 inflammasome expression in THP-1 cells, all of which were mitigated by butyrate administration. However, these protective effects of butyrate were abrogated by NLRP3 gene overexpression in THP-1. In conclusion, AS-IV can ameliorate sepsis-induced gut inflammation and barrier dysfunction by modulating M1/M2 polarization of gut macrophages, whose underlying mechanism may be restoring gut microbiome and SCFA to restrain NLRP3 inflammasome activation.

Excessive Mitochondrial Fission Suppresses Mucosal Repair by Impairing Butyrate Metabolism in Colonocytes.

Mucosal healing is one of the principal therapeutic targets for ulcerative colitis (UC). Mitochondria are dynamic organelles that undergo constant fusion and fission; however, the process that is most conducive to mucosal healing remains unclear. This study investigated the role of mitochondrial fission in mucosal healing in UC patients. Quantitative polymerase chain reaction, Western blotting, and immunostaining were used to detect mitochondrial fission in UC patients and a dextran sulfate sodium-induced colitis model. Colonic organoids were used to investigate the role of mitochondrial fission in butyrate metabolism. Enzyme activity assays were performed to identify the key proteins involved in this mechanism. It was found that inhibition of mitochondrial fission promoted mucosal healing in mice and that there was an increase in mitochondrial fission in colonic epithelial cells of UC patients. Excessive fission inhibits stem cell proliferation by impairing butyrate metabolism in colonic organoids. The mitochondrial fission antagonist P110 failed to promote mucosal healing in antibiotic-treated mice, and the addition of exogenous butyrate reversed this effect. Increased butyrate exposure in the colonic stem cell niche has also been observed in UC patients. Mechanistically, enzyme activity assays on colonic organoids revealed that excessive fission inhibits mitochondrial acetoacetyl-CoA thiolase activity via reactive oxygen species. Collectively, these data indicate that excessive mitochondrial fission suppresses mucosal repair by inhibiting butyrate metabolism and provides a potential target for mucosal healing in patients with ulcerative colitis.

Butyrate mitigates metabolic dysfunctions via the ERα-AMPK pathway in muscle in OVX mice with diet-induced obesity

The higher prevalence of metabolic syndrome (MetS) in women after menopause is associated with a decrease in circulating 17β-oestradiol. To explore novel treatments for MetS in women with oestrogen deficiency, we studied the effect of exogenous butyrate on diet-induced obesity and metabolic dysfunctions using ovariectomized (OVX) mice as a menopause model. Oral administration of sodium butyrate (NaB) reduced the body fat content and blood lipids, increased whole-body energy expenditure, and improved insulin sensitivity. Additionally, NaB induced oestrogen receptor alpha (ERα) expression, activated the phosphorylation of AMPK and PGC1α, and improved mitochondrial aerobic respiration in cultured skeletal muscle cells. In conclusion, oral NaB improves metabolic parameters in OVX mice with diet-induced obesity. Oral supplementation with NaB might provide a novel therapeutic approach to treating MetS in women with menopause.Graphical 9pYggRzUvz7mhjjMNyHPfbVideo

High-fat diet promotes colitis-associated tumorigenesis by altering gut microbial butyrate metabolism.

Background: Dietary fat intake is associated with an increased risk of colitis associated cancer (CAC). A high-fat diet (HFD) leads to systemic low-grade inflammation. The colon is believed to be the first organ suffering from inflammation caused by the infiltration of pro-inflammatory macrophages, and promotes CAC progression. We explored the role of HFD in driving CAC by altering gut microbial butyrate metabolism. Methods: Changes in the gut microbiota caused by HFD were investigated via HFD treatment or fecal microbiota transplantation (FMT). The underlying mechanisms were further explored by analyzing the role of gut microbiota, microbial butyrate metabolism, and NLRP3 inflammasome in colon tissues in a CAC mouse model. Results: HFD accelerated CAC progression in mice, and it could be reversed by broad-spectrum antibiotics (ABX). 16S-rRNA sequencing revealed that HFD inhibited the abundance of butyrate-producing bacteria in the gut. The level of short-chain fatty acids (SCFAs), especially butyrate, in the gut of mice treated with HFD was significantly reduced. In addition, treatment with exogenous butyrate reversed the M1 polarization of proinflammatory macrophages, aggravation of intestinal inflammation, and accelerated tumor growth induced by HFD; the NLRP3/Caspase-1 pathway activated by HFD in the colon was also significantly inhibited. In vitro, macrophages were treated with lipopolysaccharide combined with butyrate to detect the M1 polarization level and NLRP3/Caspase-1 pathway expression, and the results were consistent with those of the in vivo experiments. Conclusion: HFD drives colitis-associated tumorigenesis by inducing gut microbial dysbiosis and inhibiting butyrate metabolism to skew macrophage polarization. Exogenous butyrate is a feasible new treatment strategy for CAC, and has good prospect for clinical application.

Different feedback effects of aqueous end products on hydrogen production of Clostridium tyrobutyricum

Feedback inhibition is one of the main challenges of fermentative hydrogen production. In this study, the effects of butyrate and acetate on hydrogen production of Clostridium tyrobutyricum were investigated. Substrate consumption and hydrogen production were accelerated when acetate ≤15 g/L was fed. Exogenous acetate induced acetate assimilation and increased the metabolic flux of butyrate synthesis. Exogenous butyrate significantly decreased biomass formation, and slowed substrate consumption and hydrogen production. Metabolic and gene expression analyses showed that butyrate impaired glycolysis and acetate production pathway. The increased butyrate/acetate molar ratio was deemed as a strategy for cells to alleviate pH decrease and reduce the inhibition of undissociated butyric acid. Inhibition model analyses indicated butyrate was the main inhibitor in butyrate-type hydrogen production. This study demonstrates the different feedback effects of acetate and butyrate on hydrogen production of C. tyrobutyricum and provides strategies to relieve the feedback inhibition for efficient hydrogen production.

Effects of Different Monochromatic Light Combinations on Cecal Microbiota Composition and Cecal Tonsil T Lymphocyte Proliferation.

Emerging data demonstrated that the gut microbiota plays an important role in protecting the integrity of the epithelial barrier, forming a mucosal immune system, and maintaining intestinal homeostasis through its metabolites. However, the intestinal microbiota community can be affected by environmental factors, such as litter, photoperiod, or temperature. Thus, we investigated the effect of different monochromatic light combinations on cecal microbiota composition as well as explored the molecular mechanism by how the external light color information mediate cecal tonsil T lymphocyte proliferation. In this study, a total of 160 chicks were exposed to monochromatic light [red (R), green (G), blue (B), or white (W) light] or green and blue monochromatic light combination (G→B) from P0 to P42. The 16S rRNA microbial sequencing results showed that the richness and diversity of the cecum microbiota and the abundance of Faecalibacterium and Butyricicoccus were significantly increased in the G→B. With consistency in the upregulation of antioxidant enzyme ability and downregulation of pro-inflammation levels in the cecum, we observed an increase in the number of goblet cells, secretory IgA+ cells, tight junction protein (occludin, ZO-1, and claudin-1) and MUC-2 expression in the cecum of the G→B. The metabolomics analysis revealed that the relative abundance of metabolites related to butyrate was significantly increased in G→B. In an in vitro experiment, we found that butyrate could effectively induce T lymphocyte proliferation and cyclin D1 protein expression. However, these butyrate responses were abrogated by HDAC3 agonists, STAT3 antagonists, or mTOR antagonists but were mimicked by GPR43 agonists or HDAC3 antagonists. Thus, we suggested that G→B can indirectly affect the composition of cecal microbiota as well as increase the relative abundance of Faecalibacterium and Butyricicoccus and butyrate production by reducing the level of oxidative stress in the cecum. Exogenous butyrate could promote the T lymphocyte proliferation of cecal tonsil by activating the GPR43/HDAC3/p-STAT3/mTOR pathways.

Exogenous butyrate regulates lipid metabolism through GPR41-ERK-AMPK pathway in rabbits

Diets containing higher levels of fat can lead to obesity, which is potentially harmful to health. Endogenous butyric acid is produced by intestinal microbial fermentation and participates in lipid metabolism. However, there is less butyric acid produced in the body, butyric acid has a shorter half-life in the blood. We used intraperitoneal injection of sodium butyrate to study the mechanism of butyrate involved in body lipid metabolism. Triglycerides in adipose tissue and liver were significantly reduced by butyrate. The content of triglyceride in plasma in butyrate group was also significantly decreased. In adipose tissue, butyrate up-regulated gene expression of hormone-sensitive lipase (HSL), carnitine palmitoyl transferase (CPT)1 and CPT2, and increased protein expression of G protein-coupled receptor (GPR)41, phosphorylated extracellular-signal-regulated kinase (P-ERK), adenosine 5’-monophosphate (AMP)-activated protein kinase (AMPK) and P-AMPK. Gene expression of lipoprotein lipase (LPL), differentiation-dependent factor 1 (ADD1) and fatty acid synthase (FAS) was down-regulated. In liver, butyrate up-regulated protein expression of GPR41, ERK, P-ERK, P-AMPK. Gene expression of ADD1 and FAS was down-regulated. In muscle tissue, butyrate significantly up-regulated the expression of gene LPL, fatty acid transport protein (FATP) and fatty acid-binding protein (FABP) and protein GPR41, GPR43. Thus, butyrate is involved in body lipid metabolism mainly through the GPR41-mediated ERK-AMPK pathway. Inhibits lipid synthesis in adipose tissue and the liver and promotes lipolysis, avoiding obesity caused by diets with higher fat content. Highlights Butyrate affects lipid metabolism in the body by affecting lipid synthesis/decomposition in adipose tissue and liver. Butyrate mainly through GPR41-mediated ERK-AMPK pathway, inhibit lipid synthesis, promote lipid decomposition, and avoid a large amount of fat accumulation induced by higher-fat diet.

Exploiting Caenorhabditis elegans to discover human gut microbiota-mediated intervention strategies in protein conformational diseases.

Exploiting Caenorhabditis elegans to discover human gut microbiota-mediated intervention strategies in protein conformational diseases.

Campylobacter jejuni BumSR directs a response to butyrate via sensor phosphatase activity to impact transcription and colonization

Campylobacter jejuni monitors intestinal metabolites produced by the host and microbiota to initiate intestinal colonization of avian and animal hosts for commensalism and infection of humans for diarrheal disease. We previously discovered that C. jejuni has the capacity to spatially discern different intestinal regions by sensing lactate and the short-chain fatty acids acetate and butyrate and then alter transcription of colonization factors appropriately for in vivo growth. In this study, we identified the C. jejuni butyrate-modulated regulon and discovered that the BumSR two-component signal transduction system (TCS) directs a response to butyrate by identifying mutants in a genetic screen defective for butyrate-modulated transcription. The BumSR TCS, which is important for infection of humans and optimal colonization of avian hosts, senses butyrate likely by indirect means to alter transcription of genes encoding important colonization determinants. Unlike many canonical TCSs, the predicted cytoplasmic sensor kinase BumS lacked in vitro autokinase activity, which would normally lead to phosphorylation of the cognate BumR response regulator. Instead, BumS has likely evolved mutations to naturally function as a phosphatase whose activity is influenced by exogenous butyrate to control the level of endogenous phosphorylation of BumR and its ability to alter transcription of target genes. To our knowledge, the BumSR TCS is the only bacterial signal transduction system identified so far that mediates responses to the microbiota-generated intestinal metabolite butyrate, an important factor for host intestinal health and homeostasis. Our findings suggest that butyrate sensing by this system is vital for C. jejuni colonization of multiple hosts.

521-P: Sodium Butyrate Alleviates High-Glucose-Induced Renal Glomerular Endothelial Cells Pyroptosis

Caspase1-GSDMD canonical pyroptosis pathway is associated with pathogenesis of chronic inflammatory diseases. As the first layer of renal filtration barrier, whether high glucose triggers glomerular endothelial cells (GECs) pyroptosis in the pathogenesis of diabetic nephropathy (DN) is unclear. Previous research showed that the gut microbiota metabolites-butyrate, reversed high glucose induced IL-1β release in mesangial cells. However, the effects of butyrate on pyroptosis in GECs remain indistinct. Therefore, we hypothesized that high glucose may induce GECs pyroptosis and then trigger inflammatory, but sodium butyrate may alleviate it. In this study, human renal glomerular endothelial cells (HRGECs) were exposed to high glucose in vitro, exogenous sodium butyrate was used as an intervention reagent, and then caspase 1 inhibitor Ac-YVAD-CMK pre-treated or silencing GSDMD by siRNA on HRGECs. The expression of Caspase1-GSDMD signaling molecule were observed by confocal microscopy and western blotting. Propidium iodide (PI) staining-positive cells were determined using a flow cytometer. The release of IL-1β was detected and the release of lactate dehydrogenase (LDH) was assayed. Our results showed that high glucose increased the protein level of GSDMD, GSDMD-N and cleaved-caspase-1, and induced the release of IL-1β and LDH, PI positive staining cells also increased synchronously. Sodium butyrate co-treated, pretreatment with caspase-1 inhibitor or GSDMD siRNA alleviated high glucose-induced pyroptosis in HRGECs, respectively. Moreover, sodium butyrate-mediated anti-pyroptosis effect was facilitated by si-GSDMD. Overall, this is the first observation of the potential relationship between sodium butyrate and pyroptosis in the pathogenesis of DN, proved that sodium butyrate could inhibit high glucose-induced Caspase1-GSDMD canonical pyroptosis pathway, which may act as new therapeutic targets of DN. Disclosure J. Gu: None. W. Huang: None. Y. Xu: None. Y. Xu: None.

The Mode of Action of Chicory Roots on Skatole Production in Entire Male Pigs Is neither via Reducing the Population of Skatole-Producing Bacteria nor via Increased Butyrate Production in the Hindgut.

The effect of high levels of dietary chicory roots (25%) and intracecal exogenous butyrate infusion on skatole formation and gut microbiota was investigated in order to clarify the mechanisms underlying the known reducing effect of chicory roots on skatole production in entire male pigs. A Latin square design with 3 treatments (control, chicory, and butyrate), 3 periods, and 6 animals was carried out. Chicory roots showed the lowest numerical levels of skatole in both feces and plasma and butyrate infusion the highest. In the chicory group, an increased abundance of the skatole-producing bacterium Olsenella scatoligenes compared to the control group (P = 0.06), and a numerically higher relative abundance of Olsenella than for the control and butyrate groups, was observed. Regarding butyrate-producing bacteria, the chicory group had lower abundance of Roseburia but a numerically higher abundance of Megasphaera than the control group. Lower species richness was found in the chicory group than in the butyrate group. Moreover, beta diversity revealed that the chicory group formed a distinct cluster, whereas the control and butyrate groups clustered more closely to each other. The current data indicated that the skatole-reducing effect of chicory roots is neither via inhibition of cell apoptosis by butyrate nor via suppression of skatole-producing bacteria in the pig hindgut. Thus, the mode of action is most likely through increased microbial activity with a corresponding high incorporation of amino acids into bacterial biomass, and thereby suppressed conversion of tryptophan into skatole, as indicated in the literature.IMPORTANCE Castration is practiced to avoid the development of boar taint, which negatively affects the taste and odor of pork, and undesirable aggressive behavior. Due to animal welfare issues, alternatives to surgical castration are sought, though. Boar taint is a result of high concentrations of skatole and androstenone in back fat. Skatole is produced by microbial fermentation in the large intestine, and therefore, its production can be influenced by manipulation of the microbiota. Highly fermentable dietary fiber reduces skatole production. However, various theories have been proposed to explain the mode of action. In order to search for other alternatives, more efficient or less expensive, to reduce skatole via feeding, it is important to elucidate the mechanism behind the observed effect of highly fermentable dietary fiber on skatole. Our results indicate that highly fermentable dietary fiber does not affect skatole production by reducing the number of skatole-producing bacteria or stimulating butyrate production in the large intestine.

Effect of exogenous butyrate on the gastrointestinal tract of sheep. II. Hydrolytic activity in the rumen and structure and function of the small intestine.

Effect of exogenous butyrate on the gastrointestinal tract of sheep. II. Hydrolytic activity in the rumen and structure and function of the small intestine.

Effect of exogenous butyrate on the gastrointestinal tract of sheep. I. Structure and function of the rumen, omasum, and abomasum1.

Effect of exogenous butyrate on the gastrointestinal tract of sheep. I. Structure and function of the rumen, omasum, and abomasum1.

Optimization of Culture Conditions for Enhanced Butanol Production by a High Butanol Tolerant Clostridium Beijerinckii F-6

Abstract Developing microorganisms with high butanol tolerant and high production is the prerequisite for biobutanol production. In this study, a strain Clostridium Beijerinckii F-6 was evaluated for the resistance of butanol and it showed excellent butanol tolerance with the ability to grow in 2.5% (w/v) butanol. In order to enhance the performance of butanol production, various parameters affecting on butanol fermentation were optimized using statistical experimental design and analysis. Plackett-Burman design was first used to screen the most important variables influencing butanol production, and subsequently central composite design was adopted to investigate the optimum value of the selected factors for achieving maximum butanol production. Results showed that initial pH, temperature, and exogenous butyrate had significant influence on butanol production and the maximum butanol production and productivity of 7.88g/L and 0.244g/L/h were obtained at initial pH 7.0, 37.1 ℃, and addition of butyrate 1.23g/L. The results indicate that butanol tolerant strain F-6 possessed excellent butanol production performance.

Effect of exogenous butyrate on the gastrointestinal tract of sheep. II. Hydrolytic activity in the rumen and structure and function of the small intestine.

The aim of this study was to determine the effect of exogenous butyrate on the activity of carbohydrate-digesting enzymes in the reticuloruminal digesta and structure and selected functions of the small intestine in sheep. Eighteen rams (30.8 ± 2.1 kg; 12 to 15 mo of age) were fed for 14 d a diet without (CTRL) or with sodium butyrate (BUT; 36 g/kg of offered DM). Butyrate concentration in the reticuloruminal fluid and proximal small intestinal digesta was greater for BUT compared with CTRL (P ≤ 0.05). Amylolytic activity was greater, whereas cellulolytic and xylanolytic activity in the reticuloruminal digesta was less for BUT compared with CTRL (P ≤ 0.04). Relative to BW, small intestinal tissue mass and small intestine length did not differ between treatments (P ≥ 0.15); however, absolute length of the small intestine was greater for BUT compared with CTRL (P = 0.04). In the duodenum, crypt depth tended (P = 0.10) to be greater, whereas in the ileum, crypt depth and muscularis thickness tended (P = 0.10) to be less for BUT compared with CTRL. Mitosis-to-apoptosis ratio in the proximal jejunum was greater for CTRL compared with BUT (P = 0.02). Expression of G-protein-coupled receptor 43 mRNA in the duodenal epithelium was greater for BUT compared with CTRL (P < 0.01). On the other hand, peptide transporter 1 mRNA expression in the distal sections of the small intestine, as well as activity of aminopeptidase A and dipeptidylpeptidase IV, were greater for CTRL (P ≤ 0.05). In summary, exogenous butyrate supplementation in feed affects hydrolytic activity in the rumen, and increased butyrate flow out of the reticulorumen affects both proximal and distal sections of the small intestine in sheep.