Determination Of Short-chain Fatty Acids Research Articles

A Chiral-LC-MS Method for the Simultaneous Quantification of Short-Chain Fatty Acids and D/L-Lactate in the Ruminal Fluid of Dairy Cows.

Short-chain fatty acids (SCFA) and lactate in ruminal fluid are products resulting from the microbial fermentation of substrates and can be used to reflect the composition and activity of the ruminal microbiome. Determination of SCFA and D-/L-lactate in ruminal fluid currently requires two separate protocols, which is time-consuming and costly. In this study, we have optimised and validated a simple and unified 3-nitrophenylhydrazine (3-NPH) derivatisation protocol and a 20 min chiral-LC-MS method for the simultaneous quantification of all SCFA and D- and L-lactate in ruminal fluid. This method, which requires no sample pretreatment or purification shows adequate sensitivity (limit of detection (LOD): 0.01 µg/mL), satisfactory accuracy (recovery: 88-103%), and excellent reproducibility (relative standard deviation (RSD) for repeated analyses < 3% for most analytes). The application of this method to a cohort of 24 animals allowed us to reveal a large inter-cow variation in ruminal SCFA and lactate level, the concentration range for each species, the widespread correlation between different SCFA, and the strong correlation between D- and L-lactate.

The role of the gut microbiota in the genesis of gallstone formation in childhood

Cholelithiasis has been and remains a frequent socially significant public health problem worldwide. The pathomorphosis of the disease has also undergone significant changes, which has significantly rejuvenated, occurring not only at a young age, but also in childhood. More than 175,000 cholecystectomies are performed annually for cholelithiasis. Cholelithiasis affects 10-20% of the adult population in our country. At the same time, cholecystectomy came in second place after appendectomy. There are no official statistics on the prevalence of GCD in the general population of children in Russia. In the Krasnodar Territory, the incidence of cholelithiasis in childhood, according to the data of circulation, is 1.8-3.3%. Over the past decade, a number of studies have been conducted confirming the role of the microbiota in various parts of the gastrointestinal tract as a new link in the etiopathogenesis of GI. Intestinal bacteria (Clostridium, Bifidobacterium, Peptostreptococcus, Bacteroides, Eubacterium, Escherichia coli), involved in the oxidation and epimerization of bile acids, can disrupt enterohepatic circulation and lead to the formation of gallstones. At the same time, cholecystectomy leads to further transformation of the microbiota composition in various parts of the gastrointestinal tract, increasing the risk of developing stomach cancer and colorectal cancer. Further research is needed to determine the possibility of using the assessment of the composition of the gastrointestinal microbiota as a marker for the early diagnosis of various gastroenterological diseases of cholelithiasis in particular. The purpose of the study: To determine the role of the intestinal microbiota in the development of metabolic disorders in children with cholelithiasis in order to predict the complicated course of the disease. Material and methods. The work was carried out on the basis of the children’s city polyclinic No. 122 Moscow`s Health Department (chief physician - A.I. Bragin), 194 children with housing and communal services were under supervision. The control group consisted of 78 practically healthy children of the I Health group. The study groups were comparable in gender and age. Criteria for inclusion in the study: children with an established diagnosis of cholelithiasis, asymptomatic course at the age of 3 to 15 years. Exclusion criteria from the study: refusal of the child’s legal representative from the study, the presence of diagnosed acute diseases in the child during the last month, chronic somatic diseases, taking antibiotics and probiotics in the last 6 months, catamnestic observation for less than 12 months. General clinical studies were conducted: questionnaires, health assessment, anthropometry, biochemical examination of blood serum, including lipidogram, ultrasound examination of the abdominal cavity and gallbladder. To assess the intestinal microbiome, the following methods were used: standard bacteriological analysis of feces (method of sowing feces on liquid agarized nutrient media); complex coprological examination with the determination of pancreatic elastase (ELISA method) and fecal carbohydrates (Benedict method); biochemical examination of feces with the determination of short-chain fatty acids (SCFCS) (gas-liquid chromatography method); The Shannon index was adopted as a measure of intestinal dysbiosis. Statistical analysis was performed using the software package Statistica8.0 and MS OfficeExcel 2010/ The results of the study and the conclusion. The biotransformation of the bile acid pool mediated by the gut microbiota regulates the metabolism of bile, glucose and lipids. In children with GI, the number of bacteria representing the indigenous microbiota is generally lower, the intensity of colonization of the intestinal mucosa by them is significantly less, the species diversity of opportunistic and pathogenic bacteria is significantly higher compared with those in practically healthy children. There is an unstable and poor-quality system of interrelation with the macroorganism, disparate metabolic pathways. MK is not able to qualitatively maintain homeostasis within its own consortium. All this creates conditions for disruption of bile acid metabolism and the formation of lithogenic bile. The presence of intestinal dysbiosis in children with GI can cause not only the formation of gallstones, but also negatively affect the further growth and development of children, including the formation of metabolic complications and inflammatory processes.

An Improved Validated Method for the Determination of Short-Chain Fatty Acids in Human Fecal Samples by Gas Chromatography with Flame Ionization Detection (GC-FID).

Short-chain fatty acids (SCFAs) are metabolites produced by the gut microbiota through the fermentation of non-digestible carbohydrates. Recent studies suggest that the gut microbiota composition, diet and metabolic status play an important role in the production of SCFAs. The primary objective of this study was to develop a simplified method for SCFA analysis in human fecal samples by gas chromatography with flame ionization detection (GC-FID). The secondary objective was to apply the method to fecal samples collected from a clinical trial. The developed GC-FID method showed excellent linearity (R2 > 0.99994), with a limit of detection (LOD) ranging from 0.02 to 0.23 µg/mL and a limit of quantification (LOQ) ranging from 0.08 to 0.78 µg/mL. Recovery for the method ranged between 54.24 ± 1.17% and 140.94 ± 2.10%. Intra- and inter-day repeatability ranged from 0.56 to 1.03 and from 0.10 to 4.76% RSD, respectively. Nine SCFAs were identified and quantified (acetic, propionic, iso-butyric, butyric, iso-valeric, valeric, 4-methyl valeric, hexanoic and heptanoic acids) in freeze-dried fecal samples. The clinical trial compared participants with prediabetes mellitus and insulin resistance (IR-group, n = 20) to metabolically healthy participants (reference group, R-group, n = 9) following a 4-week intervention of a daily red raspberry smoothie (RRB, 1 cup fresh-weight equivalent) with or without fructo-oligosaccharide (RRB + FOS, 1 cup RRB + 8 g FOS). The statistical analysis (Student's t-test, ANCOVA) was performed on PC-SAS 9.4 (SAS Institute). Acetic acid was higher in the R-group compared to the IR-group at baseline/week 0 (p = 0.14). No significant changes in fecal SCFA content were observed after 4 weeks of either RRB or RRB + FOS.

Determination of short-chain fatty acids as putative biomarkers of cancer diseases by modern analytical strategies and tools: a review.

Short-chain fatty acids (SCFAs) are the main metabolites produced by bacterial fermentation of non-digestible carbohydrates in the gastrointestinal tract. They can be seen as the major flow of carbon from the diet, through the microbiome to the host. SCFAs have been reported as important molecules responsible for the regulation of intestinal homeostasis. Moreover, these molecules have a significant impact on the immune system and are able to affect inflammation, cardiovascular diseases, diabetes type II, or oncological diseases. For this purpose, SCFAs could be used as putative biomarkers of various diseases, including cancer. A potential diagnostic value may be offered by analyzing SCFAs with the use of advanced analytical approaches such as gas chromatography (GC), liquid chromatography (LC), or capillary electrophoresis (CE) coupled with mass spectrometry (MS). The presented review summarizes the importance of analyzing SCFAs from clinical and analytical perspective. Current advances in the analysis of SCFAs focused on sample pretreatment, separation strategy, and detection methods are highlighted. Additionally, it also shows potential areas for the development of future diagnostic tools in oncology and other varieties of diseases based on targeted metabolite profiling.

Diagnostic significance of the level of short chain fatty acids and aminothiols in the EMERCOM of Russia response officers with risk factors for circulatory system diseases

Relevance. Individuals of stressful professions, including the emergency response officers (firefighters and rescuers) of the Ministry of Emergency Situations of Russia, are prone to the early onset of circulatory system diseases (CSD). At in-depth examinations the CSD detection rate in EMERCOM response officers is above 10%. Earlier studies report that CSD risk factors are widespread among EMERCOM of Russia response officers. Therefore, it is relevant to identify the predisposition to CSD as soon as possible in order to maintain good health and longevity among highly qualified professionals of the Ministry of Emergency Situations of Russia.The pathophysiological mechanism underlying progression of atherosclerosis affects complicated interactions between vasculature, immune system and lipid metabolism. Evidence shows that intestinal microbiome exacerbates all compound risk factors for atherosclerosis, both directly and indirectly, thus playing an important role in CSD development.Numerous studies revealed that elevated levels of plasma homocysteine and other aminothiols strongly correlate with manifestations of vascular dysfunction in atherosclerosis, coronary heart disease, myocardial infarction, stroke, and thrombosis, which makes it possible to isolate homocysteine as an independent risk factor for CSD progression.Our objective is to evaluate intestinal microbiome metabolism indicators and plasma aminothiols as early CVD risk markers in emergency response officers of the Ministry of Emergency Situations of Russia.Methodology. A comprehensive clinical and laboratory examination was performed in 96 emergency response male officers of the Russian Ministry of Emergency Situations at a regular medical check-up in the outpatient center of the Nikiforov Russian Center of Emergency and Radiation Medicine, EMERCOM of Russia, St. Petersburg. The average age of response officers was (35.9 ± 0.8) years, with average work experience in the EMERCOM of Russia of (8.8 ± 0.5) years. All emergency response officers were split in 3 groups: group 1 included 56 practically healthy males, group 2 - 20 males with risk of CVD development, group 3 - 20 males with established CVD diagnosis. Chromatography with mass-spectrometric determination of short-chain fatty acids (SCFAs), trimethylamine N-oxide (TMAO) and aminothiols was performed in plasma samples from all examined patients.Results and analysis. TMAO level was elevated by 30 % in group 3 compared to group 1. Acetic acid level decrease by 32 % was found in group 2 and by 45 % in group 3 compared to group 1.Plasma valeric and butyric acids were decreased by 1.9 and 2.5 times respectively in group 3 compared to group 1, as well as by 2 times in group 3 compared to group 2. It was found that in group 3 cystine concentration was decreased by 30 % compared to group 1 and reduced glutathione was elevated by 2 times compared to group 2.Conclusion. The revealed changes in the level of SCFA, aminothiols and TMAO in emergency response officers of the Ministry of Emergency Situations of Russia indicate a metabolic imbalance, which expands our understanding of the interactions between the intestinal microbiome and human body. This is fundamentally important for CSD early diagnosis, prevention and correction in emergency response officers of the Russian Ministry of Emergency Situations.

Responses of the human gut microbiota to physiologically digested insect powders or isolated chitin thereof

As part of the quest for sustainable food choices, edible insects draw increasing attention. Nevertheless, not enough is known regarding their digestive fate and specifically little is known on the colonic fermentability of edible insects or chitin, which is found in many insects or crustaceans. This study interrogated the properties and fermentability of powders from crickets (Acheta domestica), silkworm pupae (Bombyx mori) or isolated chitin. This was done following their in vitro oral, gastric and intestinal digestion and subsequent fermentation in anaerobic bioreactors inoculated with human feces from 10 healthy volunteers. Specifically, each fecal sample was split into 5-parallel anerobic reactors fed with insect samples and fructooligosaccharides or negative control. These were sampled after 0, 5, 10 and 24 h and subjected to 16S rRNA gene sequencing and GC–MS determination of short-chain fatty acids. First, we show colloidal characteristics delineate the static in vitro digestibility of samples and the properties of effluents reaching the colon. Colonic fermentations reveal chitin significantly (p<0.05) supported an increase in biodiversity measures (e.g., alpha diversity using the Shannon index) more than whole insect powders but without any pronounced fluctuations in the production of short-chain fatty acids. Specific analyses further highlight that chitin may be partially responsible for this observation and that its isolated form may induce the growth of symbionts like members of the Ruminococcaceae and Lachnospiraceae families and the genera Faecalibacterium and Roseburia. Overall, this study suggests that chitin from insects may be a potential novel prebiotic, however further research is needed to ascertain this notion.

Determination of short-chain fatty acids by N,N-dimethylethylenediamine derivatization combined with liquid chromatography/mass spectrometry and their implication in influenza virus infection.

Short-chain fatty acids (SCFAs) are the end products of the fermentation of complex carbohydrates by the gut microbiota. Although SCFAs are recognized as important markers to elucidate the link between gut health and disease, it has been difficult to analyze SCFAs with mass spectrometry technologies due to their poor ionization efficiency and high volatility. Here, we present a novel and sensitive method for the quantification of SCFAs, including C2-C6 SCFAs and their hydroxy derivatives, by liquid chromatography/tandem mass spectrometry (LC-MS/MS) upon N,N-dimethylethylenediamine (DMED) derivatization with a run time of 10min. Moreover, the quantification method of DMED-derivatized SCFAs in intestinal contents using isotope-labeled internal standards was also established. The method validation was performed by analyzing spiked intestinal samples; the limits of detection and quantification of SCFAs with this method were found to be 0.5 and 5 fmol, respectively; the recovery was greater than 80% and good linearity (0.9932 to 0.9979) of calibration curves was obtained over the range from 0.005 to 5000pmol/μL; the intraday and interday precisions were achieved in the range of 1-5%. Furthermore, the validated method was applied to analyze SCFAs in the cecum and colon contents of mice infected with the influenza virus. The results showed that the concentration of most of the SCFAs tested here decreased significantly in a time-dependent manner after the infection, suggesting a possibility that SCFAs in intestinal samples could be used as severe disease markers. Overall, we here successfully developed a simple, fast, and sensitive method for SCFA analysis by LC-MS/MS combined with DMED derivatization. The method for the quantification of SCFAs will be a useful tool for both basic research and clinical studies.

Fiber Nanoarchitectonics for Pre-Treatments in Facile Detection of Short-Chain Fatty Acids in Waste Water and Faecal Samples.

Short-chain fatty acids (SCFAs) are among the active metabolites in biological process both in the intestinal tract and the bioconversion of organic wastes, which has resulted in various human diseases and environmental problems. In order to accurately detect SCFAs, we introduced a novel extraction sorbent. Electrospun polyacrylonitrile (PAN) nanofiber membrane was synthesized, then poly (3, 4-Ethylenedioxythiophene) (PEDOT) was deposited onto the surface of electrospun PAN nanofibers by in situ polymerization. The morphology of the composite PAN/PEDOT nanofiber was characterized by scanning electronic microscopy (SEM) and FTIR spectrum. PAN/PEDOT was used to isolate and concentrate the SCFAs in waste water and fecal samples before gas chromatography mass spectrometry (GC-MS) analysis. The analytical method was evaluated systematically, and low limits of detection (LODs) of 0.34–0.87 μg/L and good linearity (R2 ≥ 0.9953) were obtained. The method was applied successfully for the determination of SCFAs in waste water and fecal samples, with good recovery (87.5–104.6%) and satisfactory reproducibility (relative standard deviation: 6.5–14.1%). The results indicated that the proposed method can be used as a potential approach for the determination of SCFAs with high sensitivity in waste water and biological samples.

Features of the intestinal microbiota functional status in early-aged children with rotavirus infection

The aim is to assess the intestinal microflora functional and structural disorders in early-aged children in the dynamics of rotavirus infection by studying intestinal metabolites in faeces – short-chain fatty acids (SCFA).&#x0D; Materials and methods. The study included 60 breastfed children aged 1-24 months with rotavirus infection (the study group) and 30 healthy children, representative by age and sex (the comparison group). Determination of SCFA (acetate, propionate, butyrate) in faeces was carried out in all children of the study group three times in the dynamics of the disease (on the 3rd, 5th and 10th day) and in healthy children once.&#x0D; Results. The total concentration of SCFA in children with rotavirus infection was 3 and 2.2 times lower than in healthy children in the acute period of the disease (p&lt;0.01 on the 3rd and 5th day, respectively), increasing on the 10th day (p&lt;0.05), however, not reaching the normal level (p&lt;0.01). The decrease in the total pool of SCFA occurred due to all volatile acids (C2, C3, C4), the concentrations of which were lower than in healthy children (p&lt;0.01). Violation of the volatile acids ratio in their general pool was observed from the first days of rotavirus gastroenteritis in the form of an increase in the C2 relative concentration (p˂0.05) and a decrease in C3 and C4 profiles (p˂0.05). Correspondingly, a decrease in anaerobic index was noted. It was equal to 0.04 [0.01; 0.11] on the 3rd and 5th day of the disease, constituting only 1/5 of the healthy children values (p˂0,01), increasing on the 10th day to 0,09 [0,02; 0.17], however, remaining twice as lower than in children of the comparison group (p˂0,01).&#x0D; Conclusions. There is a violation of the intestinal microflora functional condition in early-aged children from the first days of rotavirus infection, which is expressed by depletion of the total pool of SCFA and concentrations of each of them, as well as structural disorders of intestinal microbiocinosis in the form of reducing its anaerobiosis. These changes are most pronounced during the first five days of rotavirus gastroenteritis and last up to 10th day of illness.

Sensitive and quantitative determination of short-chain fatty acids in human serum using liquid chromatography mass spectrometry

Short-chain fatty acids (SCFAs) are increasingly being monitored to elucidate the link between gut health and disease. These metabolites are routinely measured in faeces, but their determination in serum is more challenging due to their low concentrations. A method for the determination of eight SCFAs in serum is described here. High-resolution mass spectrometry and gas chromatography were used to identify the presence of isomeric interferences, which were then overcome through a combination of chromatographic separation and judicious choice of MS fragment ion. The SCFAs were derivatised to form 3-nitrophenylhydrazones before being separated on a reversed-phase column and then detected using liquid chromatography tandem mass spectrometry (LC-QQQ-MS). The LODs and LOQs of SCFAs using this method were in the range 1 to 7 ng mL−1 and 3 to 19 ng mL−1, respectively. The recovery of the SCFAs in serum ranged from 94 to 114% over the three concentration ranges tested.

Fast Determination of Short-Chain Fatty Acids and Glucose Simultaneously by Ultraviolet/Visible and Refraction Index Detectors via High-Performance Liquid Chromatography

A rapid analytical method for simultaneous quantification of glucose (GLC) and seven short-chain fatty acids (SCFA) was developed for detection of ruminal fermentation parameters. The formic acid (FA), lactic acid (LA), acetic acid (AA), propionic acid (PA), butyric acid (BA), isovaleric acid (IVA), valeric acid (VA), and glucose were identified and quantified by high-performance liquid chromatography (HPLC) technique, using a reverse-phase column (C-18) and simultaneous detection in UV-Vis and Refraction Index (RID) detectors, linked in series. The method was validated following the requirements of selectivity, linearity, sensitivity, limit of detection, limit of quantification, accuracy, and precision. The developed method operates in isocratic and gradient modes, providing a better SCFA separation, which allows their determination with a high accuracy and repeatability. Therefore, this study provides a fast, reliable, accurate, straightforward, and efficient alternative method for analysis of ruminal fermentation parameters by liquid chromatography using both detectors simultaneously.

Usefulness of Machine Learning-Based Gut Microbiome Analysis for Identifying Patients with Irritable Bowels Syndrome.

Irritable bowel syndrome (IBS) is diagnosed by subjective clinical symptoms. We aimed to establish an objective IBS prediction model based on gut microbiome analyses employing machine learning. We collected fecal samples and clinical data from 85 adult patients who met the Rome III criteria for IBS, as well as from 26 healthy controls. The fecal gut microbiome profiles were analyzed by 16S ribosomal RNA sequencing, and the determination of short-chain fatty acids was performed by gas chromatography–mass spectrometry. The IBS prediction model based on gut microbiome data after machine learning was validated for its consistency for clinical diagnosis. The fecal microbiome alpha-diversity indices were significantly smaller in the IBS group than in the healthy controls. The amount of propionic acid and the difference between butyric acid and valerate were significantly higher in the IBS group than in the healthy controls (p < 0.05). Using LASSO logistic regression, we extracted a featured group of bacteria to distinguish IBS patients from healthy controls. Using the data for these featured bacteria, we established a prediction model for identifying IBS patients by machine learning (sensitivity >80%; specificity >90%). Gut microbiome analysis using machine learning is useful for identifying patients with IBS.

HPLC-DAD method for the quantitative determination of short-chain fatty acids in meconium samples

The purpose of this study was to develop and validate a high-performance liquid chromatography with a diode-array detector (HPLC-DAD) method for the determination of short-chain fatty acids (SCFAs) such as: acetic, propionic, butyric, valeric and isovaleric acids in meconium. Additionally, the proposed analytical procedure was used to determine SCFAs in meconium obtained from 17 neonates. All determined organic acids in meconium samples were separated with good resolution. The HPLC system was characterized by high precision (the coefficient of variance ≤ 2.5%), high determination coefficients of calibration curves (R2>0.997) and low limits of detection (LOD) and quantification (LOQ). For all investigated organic acids, LOD ranged from 0.01 to 0.80 mmol/ kg and LOQ values ranged between 0.04 and 2.64 mmol/ kg. Recovery of the HPLC assay for individual analytes comprised the range of 90±2 - 106±2%. Concentrations of acids in meconium collected from healthy children varied in wide ranges (CV within the range 0.79–2.47%) and no regularity was found in the molar ratios of the individual acids. The validation parameters obtained in this study, made the HPLC-DAD method reliable and useful tool for the determination of short-chain fatty acids in meconium samples.

Metabolism of the intestinal microbiota in children of the first year of life with intestinal pathology and its surgical correction as a potential marker of biological age

The article presents data on the study of the metabolic activity of the intestinal microbiota in children of the first year of life. The study was performed by gas-liquid chromatographic analysis with the determination of short-chain fatty acids (SCFA) in fecal matter, which reflects the microbiota metabolic activity. The content of fecal matter was determined, reflecting the activity of aerobic microbiota-acetic acid (C2); anaerobic microbiota – propionic (C3), butyric (C4) acids; the sum of acids (E); anaerobic index (AI), which is an integral indicator of the intestinal environment. It was found that despite surgical intervention in the intestine in the first months of life, the metabolic activity of microbiota in children with intestinal resection remains stable throughout the first year of life.

The importance of the time factor in changing the qualitative composition of plaque

Relevance . Whether it comes under microbial plaque to demineralization of enamel depends on the presence of cariesogenic bacteria that exhibit proteolytic activity in relation to the organic components of the interdigital spaces of enamel, easily digestible carbohydrates that enter the oral cavity when eating, the buffer capacity of saliva, capable of neutralizing the pH of plaque within an hour to neutral values after eating. On the knowledge of these factors is based the strategy of prevention of dental caries, based on nutrition management. Of all the above, the optimal factor of influence on the cariesogenic situation in the oral cavity is the time factor – the frequency of consumption of easily digestible carbohydrates during the day. Eating easily digestible carbohydrates that can be a nutrient medium for the oral microflora is recommended only during Breakfast, lunch and dinner, but not during snacks. Purpose . To determine the value of the time factor to change the qualitative composition of plaque. Materials and methods . In a series of clinical-anamnestic and clinical-laboratory studies studied the material-plaque obtained during the examination of 137 adult young people-students aged 18 to 20 years. Plaque sampling was performed immediately after the determination of its cariesogenicity by colometric method by J. L. Hardwick and E. B. Manlay, and after 60 minutes a clinical micrometer was used to determine the short-chain fatty acids in this plaque. Results. The proposed clinical micrometod for determination of short-chain fatty acids in dental plaque stated an increase in the optical density of smears in persons with high caries resistance with a decrease in the optical density in smears in the presence of a carious process in the oral cavity. The obtained data correlate well with the indicators of cariesogenicity in plaque, which increases with a decrease in the content of short-chain fatty acids. Therefore, the content of short-chain fatty acids and dental plaque caries require an individual approach to oral hygiene in different patients. Conclusion. The optimal factor of influence on the cariesogenic situation in the oral cavity is the time factor - the frequency of consumption of easily digestible carbohydrates during the day. Eating easily digestible carbohydrates that can be a nutrient medium for the oral microflora is recommended only during breakfast, lunch and dinner.

Comparative metabolomic analysis of caecal digesta between Jinhua pig and Landrace pig

The metabolic difference in caecal digesta between Jinhua pig and Landrace pig was compared. Twenty weaned piglets at 28 days of age, including ten Landrace pigs (a Western pig breed) and ten Jinhua pigs (a Chinese native pig breed), were randomly selected and allocated into two groups. The pigs were fed the same corn-soybean diet on the same pig farm. At the age of 240 days, all pigs of each group were slaughtered, the digesta in the caecum of the twenty pigs were collected for metabolomic analysis and determination of short-chain fatty acids (SCFAs). The results showed that a total of 56 different metabolites (22 metabolites named and 34 metabolites without identification) were detected in caecal digesta using a gas chromatography time-of-flight/mass spectrometry (GC-TOF-MS)-based metabolomic approach. Forty-six of the 56 metabolites were upregulated significantly (P &amp;lt; 0.05) in Landrace group compared with Jinhua group. The metabolic pathways with different impact value in which different metabolites were mainly involved were tyrosine metabolism, citrate cycle and steroid biosynthesis. In addition, we found that Landrace accumulated more SCFAs in caecal digesta, while the concentrations of acetic acid (P &amp;lt; 0.01) and butyric acid (P &amp;lt; 0.05) in caecal digesta of Jinhua pig were markedly lower than those of Landrace pig. Collectively, our study was the first to compare the metabolic difference in caecal digesta between Jinhua pig and Landrace pig using a metabolomics approach, which might be used as a potential metabolomics mechanism to research different breeds of pigs.

Why Craft Brewers Should Be Advised to Use Bottle Refermentation to Improve Late-Hopped Beer Stability

The aromatic complexity of craft beers, together with some particular practices (use of small vessels, dry hopping, etc.), can cause more oxidation associated with pre-maturated colloidal instability, Madeira off-flavors, bitterness decrease, and aroma loss. As bottle refermentation is widely used in Belgian craft beers, the aim of the present work is to assess how this practice might impact their flavor. In fresh beers, key flavors were evidenced by four complementary techniques: short-chain fatty acids determination, esters analysis, XAD-2 extract olfactometry, and overall sensory analysis. In almost all of the fresh beers, isovaleric acid was the sole fatty acid found above its sensory threshold. Selected samples were further analyzed through natural aging at 20 °C. The presence of yeast in the bottle minimized the trans-2-nonenal released from Schiff bases and proved less deleterious than suggested by previous studies with regard to fatty acid release and ester decrease through aging. Furthermore, according to the yeast species selected, some interesting terpenols and phenols were produced from glucosides during storage.

Determination of Short-Chain Fatty Acids in Mouse Feces by High-Performance Liquid Chromatography Using 2-Nitrophenylhydrazine as a Labeling Reagent.

It has been suggested that imbalances in gut microbiota are related to diseases associated with metabolism, the central nervous system, etc. Therefore, analysis of short-chain fatty acids (SCFAs) produced by gut microbiota is very important as an indicator of causation, demonstrating the effects on the host due to changes in the gut microbiota. We developed a HPLC method for the determination of SCFAs in mouse feces. After homogenization, the SCFAs in mouse feces and 2-ethylbutyric acid (internal standard) were derivatized with 2-nitrophenylhydrazine (2-NPH) in the presence of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide. The 2-NPH derivatives of SCFAs and the internal standard were separated on a reversed-phase column (octadecyl silyl column) by gradient elution using phosphoric acid (pH 2.5)-acetonitrile at 50°C and detected by absorbance measurement at 400 nm. The recovery of the method was 90-115%, with a precision (relative standard deviation) of 1.3-7.7%. The determination of SCFAs by the present method can provide useful information for biological and clinical research.

Determination of short-chain fatty acids in feces by capillary electrophoresis with indirect UV-VIS detection

A capillary electrophoresis method enables quantification of acetate, propionate, isobutyrate and butyrate in human and canine feces.

Application of 2-Picolylamine Derivatized Ultra-high Performance Liquid Chromatography Tandem Mass Spectrometry for the Determination of Short-chain Fatty Acids in Feces Samples.

We present a sensitive and selective method for the simultaneous determination of short-chain fatty acids (SCFAs), such as acetic acid (AA), propionic acid, butyric acid (BA), isobutyric acid, valeric acid, isovaleric acid, hydroangelic acid, caproic acid, 4-methylvaleric acid and succinic acid (SA) in feces samples using a ultra-high performance liquid-chromatography tandem mass spectrometry (UHPLC-MS/MS) with simple derivatization of 2-picolylamine. The main SFCAs were derivatized in the same condition, and showed the specific product ion (m/z 109) in the electrospray positive mode regarding to 2-picolylamine. The derivatized SA showed a different pattern of the product ion (m/z 191). The derivatized analytes showed LOD < 75 nM, LOQ < 100 nM and r2 in the calibration curve > 0.991. The QuEChERS was used for sample preparation of feces samples. In the recovery test, the recovery values appeared from 89.7 to 100.2% (RSD: 2.1 to 9.2%, n = 6). This developed method was applied to evaluate obese diabetes model mice. In the result, the branched-chain SCFAs levels in feces from model mice of spontaneous obese type II diabetes were on a declining trend compared with normal. The AA levels from model mice with high-calorie/fat diet are owed a declining trend for 3 to 9 months. The BA levels showed that normal mice were increasing, and model mice had decreased tendency for breeding months. High-calorie/fat diet showed that the SA levels increased.