[Relationship between short-chain fatty acids in the gingival crevicular fluid and periodontitis of stage â ¢ or â £].

OBJECTIVE: To analyze the concentration of formic acid, propionic acid and butyric acid in gingival crevicular fluid (GCF) of patients with stages Ⅲ and Ⅳ periodontitis, and their relationship with periodontitis. METHODS: The study enrolled 37 systemically healthy patients with periodontitis and 19 healthy controls who visited Department of Periodontology, Peking University School and Hospital of Stomatology from February 2008 to May 2011. Their GCFs were collected from the mesial-buccal site of one molar or incisor in each quadrant. Periodontal clinical parameters, including plaque index(PLI), probing depth(PD), bleeding index(BI), and attachment loss(AL). Concentrations of formic acid, propionic acid and butyric acid in the supernatant of the GCFs were analyzed by high-performance capillary electrophoresis (HPCE). The prediction ability of formic acid, propionic acid and butyric acid with the risk of periodontitis and the differences between grade B and grade C periodontitis were analyzed. RESULTS: In this study, 32 patients with stage Ⅲ and 5 patients with stage Ⅳ were enrolled, including 9 patients with grade B and 28 patients with grade C. Clinical periodontal variables in the patients with periodontitis were significantly higher than those in the control group (P<0.001). Formic acid was significantly lower in periodontitis than that in the control group [5.37 (3.39, 8.49) mmol/L vs. 12.29 (8.35, 16.57) mmol/L, P<0.001]. Propionic acid and butyric acid in periodontitis were significantly higher than those in the control group: Propionic acid, 10.23 (4.28, 14.90) mmol/L vs. 2.71 (0.00, 4.25) mmol/L, P < 0.001; butyric acid, 2.63 (0.47, 3.81) mmol/L vs. 0.00 (0.00, 0.24) mmol/L, P<0.001. There was no significant difference in formic acid, propionic acid and butyric acid concentrations between grade B and grade C periodontitis (P>0.05). Propionic acid and butyric acid in the deep pocket were significantly higher than in the shallow pocket, while the concentration of formic acid decreased with the increase of PD. Propionic acid (OR=1.51, 95%CI: 1.29-1.75) and butyric acid (OR=3.72, 95%CI: 1.93-7.17) were risk factors for periodontitis, while formic acid (OR=0.87, 95%CI: 0.81-0.93) might be a protective factor for periodontitis. Propionic acid (AUC=0.852, 95%CI: 0.805－0.900), butyric acid (AUC=0.889, 95%CI: 0.841－0.937), f (formic acid, AUC=0.844, 95%CI: 0.793－0.895) demonstrated a good predictive capacity for the risk of periodontitis. CONCLUSION: The concentration of formic acid decrease in the GCF of periodontitis patients, which is a protective factor for periodontitis, its reciprocal have good predictive capacity. However, propionic acid and butyric acid increase, which are risk factors for periodontitis and have good predictive capacity. The concentration of formic acid, propionic acid, and butyric acid vary with probing depth, but there is no significant difference between grade B and grade C periodontitis.

Combined dilute alkali and milling process enhances the functionality and gut microbiota fermentability of insoluble corn fiber.

In this study, we developed a process combining dilute alkali (NaOH or NaHCO3) and physical (disk milling and/or ball milling) treatments to improve the functionality and fermentability of corn fiber. The results showed that combining chemical with physical processes greatly improved the functionality and fermentability of corn fiber. Corn fiber treated with NaOH followed by disk milling (NaOH-DM-CF) had the highest water retention (19.5 g/g), water swelling (38.8 mL/g), and oil holding (15.5 g/g) capacities. Moreover, NaOH-DM-CF produced the largest amount (42.9 mM) of short-chain fatty acid (SCFA) during the 24-hr in vitro fermentation using porcine fecal inoculum. In addition, in vitro fermentation of NaOH-DM-CF led to a targeted microbial shifting to Prevotella (genus level), aligning with a higher fraction of propionic acid. The outstanding functionality and fermentability of NaOH-DM-CF were attributed to its thin and loose structure, decreased ester linkages and acetyl groups, and enriched structural carbohydrate exposure.

Measurement of short-chain fatty acids in human plasma by means of fast gas chromatography-mass spectrometry.

A rapid and practicable analytical method for the measurement of short-chain fatty acids (SCFAs) in human plasma was developed. The extraction procedure involved the use of acidified water and methyl tert-butyl ether (MTBE), while the separation and detection of SCFAs, including acetic, propionic, and butyric acids was carried out by using gas chromatography-mass spectrometry (GC-MS) technique. The novelty of the research involves reducing the analysis time (less than 7 min) by using the novel fast GC-MS method. A narrow-bore GC capillary column of dimensions 30 m × 0.25 mm ID × 0.25 µm df with acid-modified poly(ethylene glycol) stationary phase was employed for the chromatographic separation. The signals of target compounds were acquired in selected ion monitoring (SIM) mode monitoring a quantifier ion (Q) and two qualifier ions (q1 and q2). Linearity of the method, limits of detection (LoD) and quantification (LoQ) were evaluated. In detail, regression coefficients of the calibration curves were between 0.9960 and 0.9933; LoDs ranged from 0.02 µM to 0.03 µM, while LoQs from 0.06 µM to 0.10 µM.

Short-chain fatty acids (SCFA) in infants' plasma and corresponding mother's milk and plasma in relation to subsequent sensitisation and atopic disease.

BACKGROUND: Short-chain fatty acids (SCFAs) in intestinal contents may influence immune function, while less is known about SCFAs in blood plasma. The aims were to investigate the relation between infants' and maternal plasma SCFAs, as well as SCFAs in mother's milk, and relate SCFA concentrations in infant plasma to subsequent sensitisation and atopic disease. METHODS: Infant plasma (N = 148) and corresponding mother's milk and plasma were collected four months postpartum. Nine SCFA (formic, acetic, propionic, isobutyric, butyric, succinic, valeric, isovaleric, and caproic acid) were analysed by UPLC-MS. At 12 months of age, atopic disease was diagnosed by a pediatric allergologist, and sensitisation was measured by skin prick test. All families participated in the Swedish birth cohort NICE (Nutritional impact on Immunological maturation during Childhood in relation to the Environment). FINDINGS: Infants with sensitisation, atopic eczema, or food allergy had significantly lower concentrations of five, three, and two SCFAs, respectively, in plasma at four months. Logistic regressions models showed significant negative associations between formic, succinic, and caproic acid and sensitisation [ORadj (95% CI) per SD: 0.41 (0.19-0.91); 0.19 (0.05-0.75); 0.25 (0.09-0.66)], and between acetic acid and atopic eczema [0.42 (0.18-0.95)], after adjusting for maternal allergy. Infants' and maternal plasma SCFA concentrations correlated strongly, while milk SCFA concentrations were unrelated to both. Butyric and caproic acid concentrations were enriched around 100-fold, and iso-butyric and valeric acid around 3-5-fold in mother's milk, while other SCFAs were less prevalent in milk than in plasma. INTERPRETATION: Butyric and caproic acid might be actively transported into breast milk to meet the needs of the infant, although mechanistic studies are needed to confirm this. The negative associations between certain SCFAs on sensitisation and atopic disease adds to prior evidence regarding their immunoregulatory potential. FUNDING: Swedish Research Council (Nr. 2013-3145, 2019-0137 and 2023-02217 to A-S.S.), Swedish Research Council for Health, Working Life and Welfare FORTE, Nr 2018-00485 to A.W.), The Swedish Asthma and Allergy Association's Research Fund (2020-0020 to A.S.).

Response of fulvic acid linking to redox characteristics on methane and short-chain fatty acids in anaerobic digestion of chicken manure.

Fulvic acids (FAs) is formed during the bioconversion of organic matter (OM) to biogas during anaerobic digestion (AD) and has a complex structure and redox function. However, the evolutionary mechanisms of FAs during AD and its interactions with acid and methane production have not been sufficiently investigated, especially at different stages of AD. Intermittent AD experiments by chicken manure and rice husk showed significant structural changes and reduced aromatization of FAs (e.g., O-H stretch6, 14.10-0%; SR, 0.22-0.60). The electron donating capacity (EDC) [9.76-45.39 µmole-/(g C)] and electron accepting capacity (EAC) [2.55-5.20 µmole-/(g C)] of FAs showed a tendency of decreasing and then increasing, and FAs had a stronger electron transfer capacity (ETC) in the methanogenic stage. Correlation analysis showed that the EDC of FAs was influenced by their own structure (C-O stretch2, C-H bend1, C-H bend4, and N-H bend) and also had an inhibitory effect on propionic production, which further inhibited acetic production. The EAC of FAs was affected by molecular weight and had a promoting effect on methane production. Structural equation modelling identified three possible pathways for AD. The C-O stretch2 structure of FAs alone inhibits the production of propionic. In addition, pH can directly affect the EDC of FAs. This study provides a theoretical basis for the structural and functional evolution of FAs in AD of chicken manure on the mechanism of methane production.

Changes of the Concentration of Short-Chain Fatty Acids in the Intestines of Mice with Different Types of Obesity.

We studied the production of short-chain fatty acids (SCFA) by the intestinal microbiota in mice with obesity caused by a diet and a genetic defect in the leptin receptor gene. In mice, intestinal contents were examined and SCFA were quantitatively assayed by gas chromatography. SCFA concentration in the intestinal contents of mice with alimentary obesity model was significantly lower in the first phase of the experiment (day 14), and the change in their production in dynamics was fundamentally different from this process in the control group (standard diet). The dynamics of the concentration of these metabolites in the model of genetic obesity was similar to that in the control, but the production of SCFA was significantly reduced in mice with leptin resistance in the middle phase (day 60) of the experiment. These findings indicate that the production of SCFA is more influenced by the diet than by leptin resistance.

Alterations of the gut microbiota and fecal short-chain fatty acids in women undergoing assisted reproduction.

CONTEXT: The community structure of gut microbiota changes during pregnancy, which also affects the synthesis of short-chain fatty acids (SCFAs). However, the distribution of gut microbiota composition and metabolite SCFA levels are poorly understood in women undergoing assisted reproductive technology (ART). AIMS: To evaluate the changes in gut microbiota composition and metabolic SCFAs in women who received assisted reproduction treatment. METHODS: Sixty-three pregnant women with spontaneous pregnancy (SP) and nine with ART pregnancy were recruited to provide fecal samples. Gut microbiota abundance and SCFA levels were determined by 16S ribosomal RNA (rRNA) gene amplicon sequencing and gas chromatography-mass spectrometry (GC-MS). KEY RESULTS: The ART group showed decreased alpha diversity (the species richness or evenness in a sample). The principal coordinates analysis (a method of analysing beta diversity) showed significant difference in gut microbiota between the ART group versus the SP group (unweighted UniFrac distance, R 2 =0.04, P =0.003). Proteobacteria , Blautia and Escherichia-Shigella were enriched in the ART group, whereas the relative abundance of beneficial intestinal bacteria Faecalibacterium was lower than in the SP group. Different modes of conception were associated with several SCFAs (valeric acid (r =-0.280; P =0.017); isocaproic acid (r =-0.330; P =0.005); caproic acid (r =-0.336; P =0.004)). Significantly different SCFAs between the two groups were synchronously associated with the differential gut microbiota. CONCLUSIONS: The diversity and abundance of gut microbiota and the levels of SCFAs in women undergoing ART decreased. IMPLICATIONS: The application of ART shaped the microbial composition and metabolism, which may provide critical information for understanding the biological changes that occur in women with assisted reproduction.

Role of gut microbiota on regulation potential of Dendrobium officinale Kimura & Migo in metabolic syndrome: In-vitro fermentation screening and in-vivo verification in db/db mice.

ETHNOPHARMACOLOGICAL RELEVANCE: Dendrobium officinale Kimura & Migo (DEN) is a traditional medicine in China since Han dynasty. Decoction of its stem is often used in the treatment of Type-II diabetes (T2D), which is a typical metabolic disease accompanied with the impaired metabolic function of blood glucose and lipid. AIM OF THE STUDY: Our study aimed to investigate the role of gut microbiota in differentiating DEN from different sources and its related pathway in the alleviation of metabolic syndromes induced by T2D. MATERIALS AND METHODS: The aqueous extracts of four commercially available Dendrobium (DEN-1∼4) were prepared and screened through an in-vitro fermentation system. Based on their alterations in monosaccharide composition and short chain fatty acids (SCFA) formation during fermentation with db/db faecal fluid, one DEN extract was selected for further in vivo verification. The selected Dendrobium (DEN-4) was orally administered to db/db mice for 16 days once daily at the dosage of 200 mg/kg followed by evaluating its effect on blood glucose level, liver function and intestinal microenvironment including alterations of intestinal integrity and gut microbiota composition. In addition, liver metabolomics analysis was employed to reveal the related metabolic pathways. RESULTS: Different extent of SCFA formation and utilization of monosaccharides were observed for the extracts of four DEN from different sources with a negative correlation between SCFA level and the ratio of Utilized glucose/Utilized mannose observed in the in-vitro fermentation system with db/db faecal fluid. DEN-4 with the highest SCFA formation during the in-vitro fermentation was selected and exhibited significantly hypoglycaemic effect in db/db mice with the alleviation of hepatic steatosis and impaired lipid homeostasis. Further mechanistic studies revealed that orally administered DEN-4 could improve the intestinal integrity of db/db mice via elevating their tight junction protein (ZO-1 and Occludin) expression in the colon and improve the diversity of gut microbiota with enhanced formation of SCFA. Moreover, metabolomics and KEGG pathway analysis of liver tissues suggested that the alleviated metabolic syndrome in db/db mice by DEN-4 might possibly be achieved through activation of PPAR pathway. CONCLUSION: Our current study not only revealed the potential of gut microbiota in differentiating DEN from different sources, but also demonstrated that DEN exhibited its beneficial effect on the T2D induced metabolic syndrome possibly through enhancement of intestinal integrity and activation of PPAR pathway via gut-liver axis in db/db mice.

High levels of short-chain fatty acids secreted by Candida albicans hyphae induce neutrophil chemotaxis via free fatty acid receptor 2.

Candida albicans belongs to our commensal mucosal flora and in immune-competent individuals in the absence of epithelial damage, this fungus is well tolerated and controlled by our immune defense. However, C. albicans is an opportunistic microorganism that can cause different forms of infections, ranging from superficial to life-threatening systemic infections. C. albicans is polymorphic and switches between different phenotypes (e.g. from yeast form to hyphal form). C. albicans hyphae are invasive and can grow into tissues to eventually reach circulation. During fungal infections, neutrophils in particular play a critical role for the defense, but how neutrophils are directed toward the invasive forms of fungi is less well understood. We set out to investigate possible neutrophil chemoattractants released by C. albicans into culture supernatants. We found that cell-free culture supernatants from the hyphal form of C. albicans induced both neutrophil chemotaxis and concomitant intracellular calcium transients. Size separation and hydrophobic sorting of supernatants indicated small hydrophilic factors as responsible for the activity. Further analysis showed that the culture supernatants contained high levels of short-chain fatty acids with higher levels from hyphae as compared to yeast. Short-chain fatty acids are known neutrophil chemoattractants acting via the neutrophil free fatty acid receptor 2. In line with this, the calcium signaling in neutrophils induced by hyphae culture supernatants was blocked by a free fatty acid receptor 2 antagonist and potently increased in the presence of a positive allosteric modulator. Our data imply that short-chain fatty acids may act as a recruitment signal whereby neutrophils can detect C. albicans hyphae.

Changes of the gut microbiota composition and short chain fatty acid in patients with atrial fibrillation.

Background: With the establishment of the cardiac-gut axis concept, increasing evidence has suggested the involvement and important regulatory role of the gut microbiota (GM) and short chain fatty acid (SCFA) in cardiovascular diseases. However, the relationship between GM and atrial fibrillation (AF) is still poorly understood. Objectives: The aim of this study was to investigate whether there were differences in GM and SCFA between AF patients and healthy controls. Methods: In this study, we enrolled 30 hospitalized patients with AF and 30 matched patients with sinus rhythm (SR). GM species in fecal samples were evaluated through amplicon sequencing targeting the 16Sribosomal RNA gene. The feces SCFAs were describe step by step the quantitative analysis using gas chromatography-mass spectrometry (GC-MS). GM species richness, diversity, differential abundance of individual taxa between AF and SR were analyzed. Results: AF patients showed decreased species richness and α-diversity compared to SR patients, but there was no statistical difference. The phylogenetic diversity was significant decreased in AF group. The ß-diversity indexes revealed significant differences in GM community structure between the AF group and the SR group. After investigated the individual taxa, AF group showed altered relative abundance in several taxa compared to the SR group. linear discriminant analysis (LDA) effect size (LEfSe) analysis revealed, a significant decrease in Bifidobacterium and a greater abundance of Lactobacillus, Fusobacterium, Haemophilus in AF group compared with the SR group. The abundance of haemophilus was negative correlated with isovaleric acid and isobutyric acid. Conclusions: In AF patients, the GM phylogenetic diversity and ß-diversity decreased, the relative abundance altered in several taxa and the bacterial community structure changed as well as the SCFA level. GM and SCFA dysbiosis might play a crucial part in the occurrence and development of AF.

Faecal microbiota and fatty acids in feline chronic enteropathy.

BACKGROUND: Feline chronic enteropathy is a set of disorders defined as the presence of clinical signs of gastrointestinal disease for at least three weeks. The most common final diagnoses are inflammatory bowel disease and alimentary small cell lymphoma. The etiopathogenesis of these diseases is incompletely understood; however, it is hypothesised that they involve a combination of factors, including altered composition and/or functionality of the intestinal microbiome. An important factor in the interplay of the microbiome and host is the production of short- and branched-chain fatty acids.  The aim of this study was to evaluate the possible differences in faecal microbiota diversity, composition and fatty acid production between cats suffering from chronic enteropathy and healthy cats. Sixteen cats suffering from chronic enteropathy and fourteen healthy control cats were enrolled in the study. The microbiota compositions of faecal samples were analysed by using next-generation amplicon sequencing of the V3V4 fragment of the 16S rRNA gene. Fatty acids were evaluated by high-performance liquid chromatography. RESULTS: Both the alpha and beta diversities were significantly lower in samples obtained from cats with chronic enteropathy. The relative abundance of the phylum Proteobacteria, orders Lactobacillales and Enterobacterales, family Enteriobacteriaceae and genus Escherichia Shigella were higher in diseased cats, whereas the abundance of the phylum Bacteroidota and order Peptococcales were higher in control cats. The faecal concentrations of short-chain fatty acids were higher in cats with chronic enteropathy, with lower propionate proportions and higher butyrate proportions. CONCLUSION: The study revealed alterations in microbiota compositions and short-chain fatty acid concentration in cats suffering from chronic enteropathy, which is an important finding both for research on the pathogenesis of the disease and for potential therapeutic interventions in the form of faecal microbiota transplantation and/or probiotic supplementation.

Fecal short-chain fatty acids in non-constipated irritable bowel syndrome: a potential clinically relevant stratification factor based on catabotyping analysis.

The gut microbiota is believed to be a critical factor in the pathogenesis of IBS, and its metabolic byproducts, such as short-chain fatty acids (SCFAs), are known to influence gut function and host health. Despite this, the precise role of SCFAs in IBS remains a topic of debate. In this study, we examined the bacterial community structure by 16S rRNA gene profiling and SCFA levels by UPLC-MS/MS in fecal samples from healthy controls (HC; n = 100) and non-constipated patients (IBS-D and IBS-M; NC-IBS; n = 240) enrolled in 19 hospitals in Italy. Our findings suggest a significant difference between the fecal microbiomes of NC-IBS patients and HC subjects, with HC exhibiting higher intra-sample biodiversity. Furthermore, we were able to classify non-constipated patients into two distinct subgroups based on their fecal SCFA levels (fecal catabotype "high" and "low"), each characterized by unique taxonomic bacterial signatures. Our results suggest that the fecal catabotype with higher SCFA levels may represent a distinct clinical phenotype of IBS that could have implications for its diagnosis and treatment. This study provides a new perspective on the intricate relationship between the gut microbiome and bowel symptoms in IBS, underscoring the importance of personalized strategies for its management.

Eight Weeks of Bifidobacterium lactis BL-99 Supplementation Improves Lipid Metabolism and Sports Performance through Short-Chain Fatty Acids in Cross-Country Skiers: A Preliminary Study.

(1) Background: Probiotics in the form of nutritional supplements are safe and potentially useful for strategic application among endurance athletes. Bifidobacterium animalis lactis BL-99 (BL-99) was isolated from the intestines of healthy Chinese infants. We combined plasma-targeted metabolomics and fecal metagenomics to explore the effect of 8 weeks of BL-99 supplementation on cross-country skiers' metabolism and sports performance. (2) Methods: Sixteen national top-level male cross-country skiers were recruited and randomly divided into a placebo group (C) and a BL-99 group (E). The participants took the supplements four times/day (with each of three meals and at 21:00) consistently for 8 weeks. The experiment was conducted in a single-blind randomized fashion. The subject's dietary intake and total daily energy consumption were recorded. Blood and stool samples were collected before and after the 8-week intervention, and body composition, muscle strength, blood biochemical parameters, plasma-targeted metabolomic data, and fecal metagenomic data were then analyzed. (3) Results: The following changes occurred after 8 weeks of BL-99 supplementation: (a) There was no significant difference in the average total daily energy consumption and body composition between the C and E groups. (b) The VO2max and 60°/s and 180°/s knee joint extensor strength significantly increased in both the C and E groups. By the eighth week, the VO2max and 60 s knee-joint extensor strength were significantly higher in the E group than in the C group. (c) The triglyceride levels significantly decreased in both the C and E groups. In addition, the LDL-C levels significantly decreased in the E group. (d) The abundance of Bifidobacterium animalis increased two-fold in the C group and forty-fold in the E group. (e) Plasma-targeted metabolomic analysis showed that, after eight weeks of BL-99 supplementation, the increases in DHA, adrenic acid, linoleic acid, and acetic acid and decreases in glycocholic acid and glycodeoxycholic acid in the E group were significantly higher than those in the C group. (f) Spearman correlation analysis showed that there was a significant positive correlation between Bifidobacterium animalis' abundance and SCFAs, PUFAs, and bile acids. (g) There was a significant correlation between the most significantly regulated metabolites and indicators related to sports performance and lipid metabolism. (4) Conclusions: Eight weeks of BL-99 supplementation combined with training may help to improve lipid metabolism and sports performance by increasing the abundance of Bifidobacterium, which can promote the generation of short-chain fatty acids and unsaturated fatty acids, and inhibit the synthesis of bile acids.

Isotope-Coded On-Tissue Derivatization for Quantitative Mass Spectrometry Imaging of Short-Chain Fatty Acids in Biological Tissues.

Short-chain fatty acids (SCFAs), as the main metabolites of gut microbiota, are recognized as crucial players in the host's inflammatory response and metabolic disease. Imaging the spatial distributions and calculating the accurate contents of SCFAs in the heterogeneous intestinal tissue are critical to reveal their biological functions. Here, we develop an isotope-coded on-tissue derivatization method combined with matrix-assisted laser desorption/ionization mass spectrometry imaging (MALDI-MSI) to map the spatial expressions of SCFAs in the colon tissue based on pair-labeled N,N,N-trimethyl-2-(piperazin-1-yl)ethan-1-aminium iodide (TMPA) and D3-TMPA. A noticeable increase in the MALDI-MSI sensitivity of SCFAs was achieved after on-tissue derivatization, which enables the visualization of acetic acid, propionic acid, butyric acid, valeric acid, hexanoic acid, hydroxy acetic acid, and hydroxy propionic acid in the colon tissue. Moreover, the introduction of D3-TMPA-tagged SCFAs as internal standards can significantly reduce quantitation deviation from the matrix effects, ensuring the quantitative MALDI-MSI of SCFAs. We further used this method to characterize the spatial alterations of SCFAs in the colon tissues of mice with enterocolitis. The development of this strategy provides a reliable approach to image the spatial expressions of SCFAs in tissues and paves an insight way to study the roles of SCFAs in the gut microbiota and disease.

Gastrointestinal Fermentable Polysaccharide Is Beneficial in Alleviating Loperamide-Induced Constipation in Mice.

To investigate the role of gastrointestinal (GI) polysaccharide fermentation in alleviating constipation, two polysaccharide fractions were isolated from a soluble fiber extract with determined anti-constipation activity: a 2.04 kDa neutral fraction (SSP-1) contained 99.29% glucose, and a 41.66 kDa acidic fraction (SSP-2) contained 63.85% uronic acid. After mice were given loperamide for 14 d to induce constipation, the GI transit rate increased significantly in the SSP-1 group (p < 0.05) but not in the SSP-2 group. The stool weight in the SSP-2 group was significantly higher than that in SSP-1 (383.60 mg vs. 226.23 mg) (p < 0.05). Both SSP-1 and SSP-2 groups had significantly increased serum gastrin and motilin levels (p < 0.05) and changes in their fecal short-chain fatty acid (SCFA) profiles, while SSP-1 showed better fermentation properties than SSP-2 in terms of statistically higher fecal contents of acetic acid and total SCFAs (p < 0.05). Bioinformatic analysis indicated that SSP-1 upregulated bacteria such as Oscillibacter to improve SCFA metabolism and stimulate GI hormone secretion, while SSP-2 had less influence on the gut microbiota. These results suggest that the neutral polysaccharide with superior GI fermentation properties exerted beneficial effects on constipation, while the less fermentable pectic fraction might act as a stool-bulking agent.

Development and validation of derivatization-based LC-MS/MS method for quantification of short-chain fatty acids in human, rat, and mouse plasma.

Short-chain fatty acids (SCFAs), the end products of gut microbial fermentation of dietary fibers and non-digestible polysaccharides, act as a link between the microbiome, immune system, and inflammatory processes. The importance of accurately quantifying SCFAs in plasma has recently emerged to understand their biological role. In this work, a sensitive and reproducible LC-MS/MS method is reported for SCFAs quantification in three different matrices such as human, rat and mouse plasma via derivatization, using as derivatizing agent O-benzylhydroxylamine (O-BHA), coupled with liquid-liquid extraction. First, the instrumental parameters of the mass spectrometer and then the chromatographic conditions were optimized using previously SCFAs derivatives synthetized and used as standards. After that, the best conditions for derivatization and extraction from plasma were studied and a series of determinations were performed on human, rat, and mouse plasma aliquots to validate the overall method (derivatization, extraction, and LC-MS/MS determination). The method showed good performance in terms of recovery (> 80%), precision (RSD <14%), accuracy (RE < ± 10%) and sensitivity (LOQ of 0.01 µM for acetic, butyric, propionic and isobutyric acid) in all plasma samples. The method thus developed and validated was applied to the quantification of major SCFAs in adult and aged mice, germ-free mice and in germ-free recipient mice subjected to fecal transplant from adult and aged donors. Results highlighted how plasma concentrations of SCFAs are correlated with age further highlighting the importance of developing a method that is reliable for the quantification of SCFAs to study their biological role.

The impact of protein source and grain inclusion on digestibility, fecal metabolites, and fecal microbiome in adult canines.

This study was conducted to determine the effect of animal protein inclusion rate and grain-free or grain-inclusive diets on macronutrient digestibility, fecal characteristics, metabolites, and microbiota in mixed-breed hounds and Beagles. Four experimental extruded kibble diets were made with varying amounts of animal protein and carbohydrates: 1) high animal protein, grain-inclusive (HA-GI), 2) low animal protein, grain-free (LA-GF), 3) low animal protein, grain-inclusive (LA-GI), and 4) high animal protein, grain-free (HA-GF). Thirty-two Beagles and 33 mixed-breed hounds were assigned to 1 of the 4 treatment groups in a completely randomized design that lasted 180 d. All diets were similar in chemical composition and well-digested by the animals. In general, for fecal metabolites, mixed-breed hounds had a greater concentration of total short-chain fatty acid (SCFA) and ammonia and lower indole concentration than Beagles (P < 0.05). In mixed-breed hounds, LA-GF had a greater (P < 0.05) total SCFA concentration than HA-GI and LA-GI; however, this was not observed in Beagles. There were greater concentrations of ammonia, phenol, and indole in HA-GI than in LA-GF (P < 0.05). Breed-affected fecal primary bile acid (BA) concentration, as mixed-breed hounds had a greater concentration of cholic acid (CA) than Beagles (P < 0.05). Mixed-breed hounds fed LA-GF resulted in greater CA concentrations than HA-GI and LA-GI (P < 0.05). Dogs who consumed LA-GF had lower fecal secondary BA content than the other groups (P < 0.05). The distribution of the fecal microbiota community differed in LA-GF compared with the other groups, with lower α-diversity. However, dogs fed LA-GF had the largest difference in composition with greater Selenomonadaceae, Veillonellaceae, Lactobacillaceae, Streptococcus, Ligilactobacillus, Megamonas, Collinsella aerofaciens, and Bifidobacterium sp. than the other groups. A significant breed effect was noted on nutrient digestibility, fecal metabolites, and microbiota. A treatment effect was observed in LA-GF as it resulted in greater fecal SCFA, lower protein fermentative end products, greater fecal primary BAs, lower fecal secondary BA concentrations, and shifts in fecal microbiota.

A recent topic of debate in pet food is whether grain or pulse ingredients and varying amounts of animal-based protein compared to plant proteins are better for pets' health. Thus, the need to examine ingredients used in pet food is important. This study aimed to evaluate macronutrient digestibility, fecal characteristics, fecal metabolites, and fecal microbiota in both mixed-breed hounds and Beagles when fed extruded diets containing different inclusion rates of animal protein and plant-based ingredients. Four experimental diets were studied 1) high animal protein, grain-inclusive (HA-GI), 2) low animal protein, grain-free (LA-GF), 3) low animal protein, grain-inclusive (LA-GI), and 4) high animal protein, grain-free (HA-GF). We found that all four diets were well-digested by the animals and all dogs remained healthy throughout the study. In addition, LA-GF produced a decrease in alpha diversity, yet was greater in the abundance of Megamonas, which are known to produce short-chain fatty acids. The other diets did not differ significantly. Apparent total tract nutrient digestibility, fecal characteristics, metabolites, and microbiota were affected by breed and dietary treatments. While some have postulated that pulse-rich diets could perhaps be a cause of nutrition-associated dilated cardiomyopathy in canines due to a potentially negative effect on digestibility, our results showed all diets were highly digestible.

Multispecies probiotic affects fecal short-chain fatty acids in postmenopausal women with obesity: A post hoc analysis of a randomized, double-blind, placebo-controlled study.

OBJECTIVES: Probiotics are known to regulate host metabolism. The aim of this study was to assess whether interventions with a multi-strain probiotic formula affect fecal short-chain fatty acids (SCFAs). METHODS: The analysis was carried out in 56 obese, postmenopausal women randomized to three groups: probiotic dose 2.5 × 109 CFU/d (n = 18; lower probiotic dose [LPD]), 1 × 1010 CFU/d (n = 18; higher probiotic dose [HPD]), or placebo (n = 20). RESULTS: An increase in three SCFA fecal concentrations in the HPD group was observed: acetic acid (C2; effect [E] = 1.72, SE = 0.73; 95% confidence interval [CI], 0.28-3.16; P = 0.019), butyric acid (C4; E = 0.98, SE = 0.46; 95% CI, 0.08-1.88; P = 0.033), and valeric acid (C5; E = 0.68, SE = 0.23; 95% CI, 0.23-1.12; P = 0.003). The mediation analysis showed that the decrease in uric acid under HPD may be transmitted through the elevation of C5 content. Multi-strain probiotic increases the SCFA content in the stool in a dose-dependent manner, which may diminish some cardiovascular risk factors because of a reduction in blood uric acid levels. CONCLUSION: Assessing long-term health benefits requires further research, including assessment of blood SCFA concentrations and multiomic and mechanistic approaches.

Pretreatment of free nitrous acid combined with calcium hypochlorite for enhancement of hydrogen production in waste activated sludge.

A variety of variables limit the recovery of resources from anaerobic fermentation of waste activated sludge (WAS), hence pretreatment strategies are necessary to be investigated to increase its efficiency. A combination of free nitrous acid (FNA) and calcium hypochlorite [Ca(ClO)2] was employed in this investigation to significantly improve sludge fermentation performance. The yields of cumulative hydrogen for the blank and FNA treatment group were 1.09 ± 0.16 and 7.36 ± 0.21 mL/g VSS, respectively, and 6.59 ± 0.24 [0.03 g Ca(ClO)2/g TSS], 7.75 ± 0.20 (0.06), and 8.58 ± 0.22 (0.09) mL/g VSS for the Ca(ClO)2 groups. The co-treatment greatly boosted hydrogen generation, ranging from 39.97 ± 2.26 to 76.20 ± 4.78 % as compared to the solo treatment. Mechanism analysis demonstrated that the combined treatment disturbed sludge structure and cell membrane permeability even more, which released more organic substrates and enhanced biodegradability of fermentation broth. This paper describes a unique strategy to sludge pretreatment that expands the use of Ca(ClO)2 and FNA in anaerobic fermentation, with implications for sludge disposal and energy recovery.

Effects of whole-grain cereals on fecal microbiota and short-chain fatty acids in dogs: a comparison of rye, oats and wheat.

Dietary fiber in dog food is reported to promote healthy gut microbiota, but few studies have investigated the effects of whole-grain cereals, which contain a variety of fiber types and other bioactive compounds. The aim of the present study was to compare the effects of diets containing whole-grain rye (RYE), oats (OAT) and wheat (WHE) on fecal microbiota and short-chain fatty acid production. Eighteen dogs were fed three experimental diets, each for four weeks, in a cross-over design. Fecal samples were collected at the end of each diet period. Analysis of 16S rRNA gene amplicons showed that family Lachnospiraceae and genus Bacteroides were the gut microbial groups most affected by diet, with lowest relative abundance following consumption of RYE and a trend for a corresponding increase in genus Prevotella_9. Fecal acetate and propionate concentrations were higher after consumption of RYE compared with OAT. In conclusion, rye had the strongest effect on gut microbiota and short-chain fatty acids, although the implications for dog gut health are not yet elucidated.