Isobutyric Acid Research Articles

Copper foam supported g-C3N4-metal–organic framework bacteria biohybrid cathode catalyst for CO2 reduction in microbial electrosynthesis

Microbial electrosynthesis (MES) presents a versatile approach for efficiently converting carbon dioxide (CO2) into valuable products. However, poor electron uptake by the microorganisms from the cathode severely limits the performance of MES. In this study, a graphitic carbon nitride (g-C3N4)-metal–organic framework (MOF) i.e. HKUST-1 composite was newly designed and synthesized as the cathode catalyst for MES operations. The physiochemical analysis such as X-ray diffraction, scanning electron microscopy (SEM), and X-ray fluorescence spectroscopy showed the successful synthesis of g-C3N4-HKUST-1, whereas electrochemical assessments revealed its enhanced kinetics for redox reactions. The g-C3N4-HKUST-1 composite displayed excellent biocompatibility to develop electroactive biohybrid catalyst for CO2 reduction. The MES with g-C3N4-HKUST-1 biohybrid demonstrated an excellent current uptake of 1.7 mA/cm2, which was noted higher as compared to the MES using g-C3N4 biohybrid (1.1 mA/cm2). Both the MESs could convert CO2 into acetic and isobutyric acid with a significantly higher yield of 0.46 g/L.d and 0.14 g/L.d respectively in MES with g-C3N4-HKUST-1 biohybrid and 0.27 g/L.d and 0.06 g/L.d, respectively in MES with g-C3N4 biohybrid. The findings of this study suggest that g-C3N4-HKUST-1 is a highly efficient catalytic material for biocathodes in MESs to significantly enhance the CO2 conversion.

Therapeutic effect of total flavonoids of Sargentodoxa cuneata on ulcerative colitis in mice by correcting gut dysbiosis

Sargentodoxa cuneata is a traditional Chinese herb commonly used for the treatment of ulcerative colitis (UC) in clinical practice. However, the effects of total flavonoids of Sargentodoxa cuneata (TFSc) remain unclear. In this study, we explored the effects and mechanisms of action of TFSc in mice with dextran sulfate sodium-induced UC. The TFSc components were identified using liquid chromatography-tandem mass spectrometry. Mice with UC were orally administered TFSc to evaluate its effects on colon and liver damage. Changes in gut microbiota were analyzed using 16S rRNA gene sequencing. Moreover, the levels of short-chain fatty acids (SCFAs) and few organic acids in the intestinal contents were measured. Furthermore, the correlation amongst gut flora, SCFAs, and organic acids was studied. A total of 304 compounds were identified. TFSc alleviated the symptoms of UC in mice, inhibited weight loss, reduced the disease activity index, and improved colon shortening along with cardiac and hepatic indices. Furthermore, TFSc mitigated pathological changes in the colon and liver, and reduced the TNF-α levels in colon tissues of mice with UC. TFSc also modulated intestinal flora disorders, increased the levels of four SCFAs (isocaproic acid, 3-hydroxyisovaleric acid, isobutyric acid, and ethylmethylacetic acid), and decreased the levels of two organic acids (malonic acid and succinic acid). The differential regulation of SCFAs and organic acids by TFSc was strongly associated with specific gut flora. TFSc showed potential for improving colon and liver injury in mice with UC by regulating the intestinal flora and associated metabolites (SCFAs and organic acids). These findings provide new evidence for developing TFSc as a drug for treating UC and UC-related liver injuries.

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 β-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 β-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.

Identification of Sars-Cov-2 related volatile organic compounds from face masks

This study aims to identify SARS-CoV-2-related volatile organic compounds (VOCs) of the exhaled breath from face masks. Face masks collected from SARS-CoV-2 patients (n = 30) and the control group (n = 11) were analyzed to detect VOCs in the exhaled breath using the Headspace-Gas Chromatography Mass Spectrometry. Significant increases in concentrations of toluene, hexadecane, and phenol were detected in the face masks belonging to patient groups (p < 0.001). Clinical significance was further found in isobutyric acid levels considering Cohen's d value (p = 0.070). The findings of this study suggest that monitoring toluene, hexadecane, phenol, and isobutyric acid could provide considerable support in rapid screening of SARS-CoV-2.

Formation of key aroma-active and off-flavor components in concentrated peach puree

Non-volatiles offer some insight into the formation of aroma-active components in peach puree (PP), but more depth investigation is still needed. Formation pathways of key aroma-active and off-flavor components in PP during thermal concentration (PP + C) and sterilization (PP + C + S) are unclear. Therefore, GC-O-MS combined with UPLC-MS/MS was used to identify the volatile and nonvolatile components and their formation pathways. Among the 36 aroma-active compounds, the contents of γ-decalactone, hexyl acetate, leaf acetate, hexanal, and 1-hexanol (odor activity value ≥ 1) decreased by 46 %, 100 %, 100 %, 92 %, and 100 % between PP and PP + C + S, causing the weakening of “green” and “fruity” attributes. Off-flavor components including 1-octen-3-one, isobutyric acid, isothiazole, and isovaleric acid were identified during thermal processing. 1-Octen-3-one content increased by 75 % from PP to PP + C + S through linolenic acid metabolism, which contributed to “cooked”; the formation of isobutyric and isovaleric acids, isothiazole, resulted in the enhancement of “sour/rancid” via serine and leucine metabolism.

Metabolomic analysis of serum short-chain fatty acid concentrations in a mouse of MPTP-induced Parkinson's disease after dietary supplementation with branched-chain amino acids.

The gut microbiota and microbial metabolites influence the enteric nervous system and the central nervous system via the microbial-gut-brain axis. Increasing body of evidence suggests that disturbances in the metabolism of peripheral branched-chain amino acids (BCAAs) can contribute to the development of neurodegenerative diseases through neuroinflammatory signaling. Preliminary research has shown that longitudinal changes in serum amino acid levels in mouse models of Parkinson's disease (PD) are negatively correlated with disease progression. Therefore, the aim of the present study was to determine the changes in serum levels of short-chain fatty acids (SCFAs) in a mouse model of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced PD after dietary BCAA supplementation. In our research, gas chromatography-mass spectrometry was used to detect serum SCFA concentrations. The data were then analyzed with principal component analysis and orthogonal partial least squares discriminant analysis. Finally, the correlations of serum SCFA levels with gut and motor function in MPTP-induced PD mice were explored. Propionic acid, acetic acid, butyric acid, and isobutyric acid concentrations were elevated in MPTP + H-BCAA mice compared with MPTP mice. Propionic acid concentration was increased the most, while the isovaleric acid concentration was decreased. Propionic acid concentration was positively correlated with fecal weight and water content and negatively correlated with the pole-climbing duration. In conclusion, these results not only suggest that propionic acid may be a potential biomarker for PD, but also indicate the possibility that PD may be treated by altering circulating levels of SCFA.

Lewis Acid-Base Adducts of α-Amino Acid-Derived Silaheterocycles and N-Methylimidazole

In chloroform solution, the reaction of bis(tert-butylamino)dimethylsilane ((tBuNH)2SiMe2) and an α-amino acid (α-amino isobutyric acid, H2Aib; D-phenylglycine, H2Phg; L-valine, H2Val) in the presence of N-methylimidazole (NMI) gave rise to the formation of the pentacoordinate silicon complexes (Aib)SiMe2-NMI, (Phg)SiMe2-NMI and (Val)SiMe2-NMI, respectively. Therein, the amino acid building block was a di-anionic bidentate chelator at the silicon atom. In solution, the complexes were involved in rapid coordination–dissociation equilibria between the pentacoordinate Si complex (e.g., (Aib)SiMe2-NMI) and its constituents NMI and a five-membered silaheterocycle (e.g., (Aib)SiMe2), as shown by 29Si NMR spectroscopy. The energetics of the Lewis acid-base adduct formation and the competing solvation of the NMI molecule by chloroform were assessed with the aid of computational methods. In CDCl3 solution, deuteration of the silaheterocycle NH group proceeded rapidly, with more than 50% conversion within two days. Upon cooling to −44 °C, the chloroform solvates of the adducts (Aib)SiMe2-NMI and (Phg)SiMe2-NMI crystallized from their parent solutions and allowed for their single-crystal X-ray diffraction analyses. In both cases, the Si atom was situated in a distorted trigonal bipyramidal coordination sphere with equatorial Si–C bonds and an equatorial Si–N bond (the one of the silaheterocycle). The axial positions were occupied by a carboxylate O atom of the silaheterocycle and the NMI ligand’s donor-N-atom.

Metabolome panels as potential noninvasive biomarkers for primary glomerulonephritis sub-types: meta-analysis of profiling metabolomics studies

Primary glomerulonephritis diseases (PGDs) are known as the top causes of chronic kidney disease worldwide. Renal biopsy, an invasive method, is the main approach to diagnose PGDs. Studying the metabolome profiles of kidney diseases is an inclusive approach to identify the disease’s underlying pathways and discover novel non-invasive biomarkers. So far, different experiments have explored the metabolome profiles in different PGDs, but the inconsistencies might hinder their clinical translations. The main goal of this meta-analysis study was to achieve consensus panels of dysregulated metabolites in PGD sub-types. The PGDs-related metabolome profiles from urine samples in humans were selected in a comprehensive search. Amanida package in R software was utilized for performing the meta-analysis. Through sub-type analyses, the consensus list of metabolites in each category was obtained. To identify the most affected pathways, functional enrichment analysis was performed. Also, a gene-metabolite network was constructed to identify the key metabolites and their connected proteins. After a vigorous search, among the 11 selected studies (15 metabolite profiles), 270 dysregulated metabolites were recognized in urine of 1154 PGDs and control samples. Through sub-type analyses by Amanida package, the consensus list of metabolites in each category was obtained. Top dysregulated metabolites (vote score of ≥ 4 or ≤ − 4) in PGDs urines were selected as main panel of meta-metabolites including glucose, leucine, choline, betaine, dimethylamine, fumaric acid, citric acid, 3-hydroxyisovaleric acid, pyruvic acid, isobutyric acid, and hippuric acid. The enrichment analyses results revealed the involvement of different biological pathways such as the TCA cycle and amino acid metabolisms in the pathogenesis of PGDs. The constructed metabolite-gene interaction network revealed the high centralities of several metabolites, including pyruvic acid, leucine, and choline. The identified metabolite panels could shed a light on the underlying pathological pathways and be considered as non-invasive biomarkers for the diagnosis of PGD sub-types.

Effect of different doses of cobalt on rumen digestion in cattle

Optimization of mineral nutrition is a necessary measure to maintain high productivity of beef cattle which often lack minerals in their feed. The innovative base in this case can be ultrafine particles of essential elements characterized by high bioavailability in a small dose. The effect of ultrafine Co3O4 particles on the digestibility of dry matter of feed in the in vitro system (artificial rumen), the amount of volatile fatty acids, nitrogen forms (total, non-protein, ammonia, urea, protein) and on the amino acid composition (arginine, lysine, methionine, alanine, glycine) of animal rumen fluid was studied. The research was conducted in 2023. Cattle of the Kazakh white-headed breed aged 11-12 months with an average weight of 265-275 kg were used as an object of research. It was found that in in vitro studies, dry matter digestibility of feed was 9.0% higher at a concentration of 0.36 g/mL of Co3O4 ultrafine particles. Analysis of volatile fatty acid concentration showed that this dosage increases acetic acid, propionic acid, butyric acid, valerianic acid, and caproic acid. The introduction of ultrafine Co3O4 particles increased the content of protein nitrogen and total nitrogen in the experimental animals, indicating the intensification of rumen microbiocenosis. At introduction of ultrafine Co3O4 particles, shifts in the amino acid composition of the rumen contents were observed, which may be caused by the changes in the nature of nitrogenous substances transformation in the digestive tract. It is concluded that the use of ultrafine Co3O4 particles has a positive effect on the digestive processes in the rumen.

Infant gut microbiota and negative and fear reactivity.

Studies indicate that gut microbiota is related to neurodevelopmental and behavioral outcomes. Accordingly, early gut microbiota composition (GMC) has been linked to child temperament, but research is still scarce. The aim of this study was to examine how early GMC at 2.5 months is associated with child negative and fear reactivity at 8 and 12 months since they are potentially important intermediate phenotypes of later child psychiatric disorders. Our study population was 330 infants enrolled in the longitudinal FinnBrain Birth Cohort Study. Gut microbiota composition was analyzed using stool sample 16s rRNA sequencing. Negative and fear reactivity were assessed using the Laboratory Temperament Assessment Battery (Lab-TAB) at child's age of 8 months (n =150) and the Infant Behavior Questionnaire-Revised Short Form (IBQ-R SF) at child's age of 12 months (n = 276). We found a positive association between alpha diversity and reported fear reactivity and differing microbial community composition based on negative reactivity for boys. Isobutyric acid correlated with observed negative reactivity, however, this association attenuated in the linear model. Several genera were associated with the selected infant temperament traits. This study adds to the growing literature on links between infant gut microbiota and temperament informing future mechanistic studies.

Employing Spent Frying Oil as a Feedstock to Produce Short-Chain Organic Acids Using Mixed Microbial Cultures

Food industry waste and wastewater have been explored in relation to acidogenic fermentation as sources of non-competing food carbohydrates and mixed microbial cultures (MMCs), respectively, with the aim of producing short-chain organic acids (SCOAs) with general applications in polyhydroxyalkanoates (PHAs) production. However, studies on acidogenic fermentation using lipidic substrates are scarce. In this work, it was hypothesized that spent frying oil (SFO) could be used as a substrate for SCOA production via MMCs. In this study, oleic acid was used as a model molecule. The characterization of SFO revealed that it is mainly composed of oleic acid (81%), with minor amounts of palmitic, linoleic, and stearic acids. Different MMCs and food-to-microorganism (F/M) ratios were tested. MMCs collected in the aerobic tank of a municipal wastewater treatment plant (AES), at a 1:1 F/M, allowed to obtain the highest SCOA concentration (1.50 g COD/L) and the most diverse profile of SCOAs, with the production of acetic, propionic, butyric, iso-butyric, and valeric acids at 48:17:9:13:13% on a molar basis, respectively. This variety of odd and even SCOAs is of upmost importance, with potential applications in producing PHAs. This work can be considered a starting point for future acidogenic fermentation studies using lipid-based substrates and for the future production of PHAs.

PSXIII-22 Effects of Isoacids on Rumen Ph, Microbial Protein and in Situ Dry Matter Disappearance in Beef Heifers Fed Growing Diet

Abstract The objective of this study was to evaluate effects of feeding supplemental isoacids in a growing diet on parameters of rumen fermentation and in situ DM disappearance. Eight mature ruminally cannulated beef heifers (Angus crossbred; mean BW 618 ± 31 kg) were used in a replicated 4 x 4 Latin square design. Heifers were housed in individual pens and fed the following treatment diets: no supplemental isoacids (ISO) in the basal diet (Control); 7.2 g of 2-methylbutyric acid· animal-1· day-1 (ISO1); 7.2 g of 2-methylbutyric + 7.2 g isobutyric acids· animal-1· day-1 (ISO2); and 7.2 g 2-methylbutyric + 7.2 g isobutyric + 7.2 g isovaleric acid· animal-1· day-1 (ISO3). Basal diet consisted of (DM basis) 26.9% wheat hay, 35.5% steam flaked corn, 22.6% wet corn gluten feed, 12.3% DDG, and 2.7% mineral/vitamin supplement. Each experimental period lasted 28 d, with 21 d for diet adaptation and 7 d for data and sample collection. On day 1 of each sampling period ruminal fluid was collected 2 hours before and 1, 3, 7 and 10 hours after morning feeding. The pH of ruminal contents was immediately measured with an electrode pH meter. Urine samples (approximately 200 mL) were collected on day 2 of each sampling period 4 h after the feeding and filtered to remove particles. Urine was analyzed for creatinine, uric acid, and allantoin. Bags were placed into rumen for 72, 48, 36, 24, 12, 8, 4 and 0 hours and all bags were removed at same time on the end of incubation (hour 0), rinsed with tap water and dried at 55°C. Data were analyzed using the MIXED procedure of SAS. A contrast was observed (P = 0.029) for overall rumen pH between control versus isoacid treatments (6.44 vs 6.31). Uric acid, allantoin, total purines and intestinal flow of microbial nitrogen were not affected by treatments (P ≥ 0.10) with overall means of 10.47, 328.80, 339.27 mmol/d and 246.64 g N/d, respectively. Overall, no effects were observed for in situ dry matter disappearance (P ≥ 0.10). However, at hour 4 differences between ISO2 and ISO3 (P = 0.02; 44.89% vs 38.45%) and ISO2 and ISO4 (P = 0.05; 44.89% vs 39.75%) were observed. No effects of in situ DM disappearance was observed (P ≥ 0.10). Supplementing beef heifers with isoacids may reduce rumen pH as a result of increased ruminal volatile fatty acid production; however, supplemental ISO in this study did not affect microbial nitrogen synthesis or dry matter in situ disappearance. Further analyses are currently in progress.

PSV-12 The Influence of Trace Mineral Source on Rumen Trace Mineral Solubility and In-Vitro Fiber Digestion in Steers Fed a Lactating Dairy Diet

Abstract Eight individually fed fistulated steers (410 ± 10 kg) were used to investigate the impact of trace mineral source on rumen trace mineral solubility and in vitro fermentation characteristics. Steers were sorted by body weight, into two trace mineral (TM) treatment groups (n = 4/treatment). Treatments consisted of TM supplementation at 10 mg Cu, 40 mg Mn, and 60 mg Zn/kg DM from either sulfate TM (STM) or hydroxy TM (HTM) sources. Steers were fed a diet balanced to meet the nutrient requirements (TMR) for lactation dairy cow. Dietary TM treatments were mixed with dried distillers grains and top dressed daily. Rumen contents were collected at 0, 2, and 4 h post feeding on d 1 and 14 of the experiment. Rumen samples were centrifuged at 1,500 × g for 15 min. The supernatant and the digesta pellet were frozen, separately, at −20°C for TM analysis. On d 15 of the experiment, approximately 500 g (wet weight) of rumen contents were collected from each steer 2 hours post-feeding. Strained ruminal fluid (SRF) was obtained by squeezing the rumen contents through 2 layers of cheese cloth. The retained digesta (150 g wet weight) was washed with 2.2 L pre-warmed McDougall’s buffer to remove particle associated microorganism (PAO). The SRF and the PAO were then filtered through 8 layers of cheesecloth, separately, and mixed at a ratio of 1:2 (SRF:PAO). The SRF:PAO mixture for each steer was incubated with the TMR containing HTM and a separate incubation with the TMR containing STM for 0, 12, and 24 h (3 replicate in vitro tubes/animal/TMR treatment) at 39°C under anaerobic conditions. After each incubation time, samples were centrifuged at 1,500 x g. The supernatant was removed and frozen at -20°C for VFA analysis. The digesta pellet was dried at 60°C and DM, NDF, and ADF digestibility determined. Data were analyzed as a completely randomized block design with individual animal as the experimental unit. There was a treatment x day x sample type interaction for rumen Zn (P &amp;lt; 0.04) and Mn (P &amp;lt; 0.03) concentrations. Zinc and Mn concentrations were greater in digesta and lesser in supernatant in STM compared with HTM supplemented animals. Rumen distribution of Cu was not impacted by TM source. In vitro molar proportions isobutyric acid were greater (P &amp;lt; 0.01) in HTM compared with STM supplemented animals, while the molar proportion of propionic acid were greater (P &amp;lt; 0.01) in STM supplemented animals. Total VFA concentration, molar proportions of acetic and propionic acid, and DM, NDF, and ADF digestibility were not impacted by dietary trace mineral source or rumen fluid source. These data may indicate that the source of trace mineral can influence trace mineral solubility in the rumen.

Disturbance of Adaptive Immunity System Was Accompanied by a Decrease in Plasma Short-Chain Fatty Acid for Patients Hospitalized During SARS-CoV-2 Infection After COVID-19 Vaccination.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection can lead to disorders of immune function and a decrease in the diversity of intestinal flora. We aimed to explore the changes of circulating immune cell subsets and the plasma level of intestinal short-chain fatty acids (SCFAs) in patients with Coronavirus disease 2019 (COVID-19), further understanding the pathogenesis of COVID-19. The study included 83 newly diagnosed COVID-19 patients and 39 non-COVID-19 controls. All have completed a full course of vaccination against SARS-CoV-2. The levels of peripheral lymphocyte subsets and plasma cytokines were detected by flow cytometry. Targeted metabolomics was used to explore the level of SCFAs in plasma. Compared with the non-COVID-19 group, COVID-19 patients showed a decrease in CD19+B cells, CD4+T cells, CD8+T cells, NK cells, CD4+CD8+T cells and CD4-CD8-T cells (all p<0.001) and concomitantly an increase in sIL-2R, IL-6 and IL-10 (all p<0.005). These alterations were more pronounced in those critical patients. In addition, COVID-19 patients had lower levels of propanoic acid (PA), butyric acid (BA), isobutyric acid (IBA) and isohexanoic acid (ICA) (all p<0.01). Among them, the level of ICA is positively correlated with the absolute number of immune cells. Our study suggests the immune cell subsets in COVID-19 patients who had completed vaccination were still severely disturbed and concomitantly lower SCFAs, especially in severe patients with poor prognosis. Lower levels of plasma SCFAs may contribute to lymphopenia in COVID-19. The potential relationship between plasma SCFAs and immune cell reduction provides a new direction for the treatment of COVID-19.

High-fibre diets regulate antioxidative capacity and promote intestinal health by regulating bacterial microbiota in growing pigs.

This experiment was conducted to investigate the effects of a high-fibre diet on growth performance, nutrients digestibility, intestinal health, and intestinal microbiota composition of growing pigs. Twelve healthy "Duroc × Landrace × Yorkshire" castrates (49 ± 1.35 kg) were randomly divided into two groups with six replicates and one pig per replicate. The two diet treatments were fed the basal diet (CON) based on corn and soybean meal and high fibre diet (HF)respectively. The nutritional levels of the two treatments were the same. The experiment lasted 28 days. The results showed that the addition of 16% wheat bran fibre to the diet of growing pigs did not affect growth performance (p > 0.05). Compared with the CON, contents of isobutyric and butyric acid, GSH-PX and T-AOC in serum were increased in the HF. It decreased the gross energy digestibility and acetic acid content in feces of growing pigs (p < 0.05), the contents of GSH-PX and T-AOC in serum. It decreased the gross energy digestibility and acetic acid content in feces of growing pigs (p < 0.05). Compared with the CON, the Shannon, and Chao1 indexes of the HF were increased (p < 0.05). At the phylum level, the abundance of g_Lactobacillus increased in the HF (p < 0.05). Correlation analysis showed that a total of 18 microbial genera were correlated with antioxidant capacity and volatile fatty acid levels (p < 0.05). In summary, this study showed that adding 16% wheat bran to the diet of growing pigs had no effect on growth performance but helped to improve the richness and stability of intestinal microbiota, promote posterior intestinal fermentationand increase serum antioxidant capacity.

Non-targeted metabolomics aids in sex pheromone identification: a proof-of-concept study with the triangulate cobweb spider, Steatoda triangulosa

Targeted metabolomics has been widely used in pheromone research but may miss pheromone components in study organisms that produce pheromones in trace amount and/or lack bio-detectors (e.g., antennae) to readily locate them in complex samples. Here, we used non-targeted metabolomics—together with high-performance liquid chromatography–mass spectrometry (HPLC–MS), gas chromatography-MS, and behavioral bioassays—to unravel the sex pheromone of the triangulate cobweb spider, Steatoda triangulosa. A ternary blend of three contact pheromone components [N-4-methylvaleroyl-O-isobutyroyl-l-serine (5), N-3-methylbutyryl-O-isobutyroyl-l-serine (11), and N-3-methylbutyryl-O-butyroyl-l-serine (12)] elicited courtship by S. triangulosa males as effectively as female web extract. Hydrolysis of 5, 11 and 12 at the ester bond gave rise to two mate-attractant pheromone components [butyric acid (7) and isobutyric acid (8)] which attracted S. triangulosa males as effectively as female webs. Pheromone components 11 and 12 are reported in spiders for the first time, and were discovered only through the use of non-targeted metabolomics and GC–MS. All compounds resemble pheromone components previously identified in widow spiders. Our study provides impetus to apply non-targeted metabolomics for pheromone research in a wide range of animal taxa.

In vitro digestion and fecal fermentation of encapsulated starch constructed via layer-by-layer coating of calcium alginate

This research prepared functional-resistant starch capsules by constructing multiple calcium alginate shells around calcium alginate/starch beads. Scanning electron microscopy revealed a dense structure for each layer of the calcium alginate shell, tightly encapsulating the calcium alginate/starch beads. The rapidly digestive starch content of three-layer calcium alginate shelled starch capsules decreased to 0.50 ± 1.14%, while the resistant starch content increased to 78.25 ± 1.55%. The estimated glycemic index (eGI) experiment suggested that the two-layer shell capsules (eGI: 59.91) and Three-layer shell capsules (eGI: 47.75) were classified as low-glycemic index foods. Furthermore, calcium alginate/corn starch multilayer capsules showed reduced microbial gas production and increased concentrations of propionic acid, isobutyric acid, and valeric acid compared to lactulose in vitro fecal fermentation experiment. Moreover, three-layer capsules and beads promoted a relative abundance of Bacteroidetes but inhibited the reproduction of Proteobacteria and Actinobacteria compared with lactulose and corn starch. These results suggest that constructing multi-layered sodium alginate shells for starch beads can effectively increase the digestive resistance of starch within the capsules and control its fermentation in the colon. This study will have a profound impact on the development of RS1-type resistant starch and be beneficial in the design and production of functional foods for prevention and assistance in the treatment of chronic diseases such as diabetes and obesity.

Dietary NDF/Starch Ratio Modulates Colonic Microbiota and Metabolites in Lambs before and after Weaning

The neutral detergent fiber (NDF)/starch ratio is a key determinant of the carbohydrate composition in ruminant diets, which affects the development of the gastrointestinal tract and animal growth. In this study, we used a combination of 16S amplicon sequencing and metabolomics technologies to reveal changes in the microbiota and their metabolites associated with digestive matter in the colon of lambs between different starter NDF/starch ratios and before and after weaning. A total of 40 male lambs of Hu sheep with a newborn weight of 3.14 ± 0.05 kg were selected for the experiment and fed with breast milk until 10 days of age, and were randomly divided into 2 groups, which were fed ad libitum with a starter of NDF/starch of 0.5 (A) or 1.0 (B) for a period of 56 days, and then weaned off the milk powder at 35 days of age. Six lambs with weights close to the average weight of the group were selected for slaughter in each of the two groups before (35 days of age) and after weaning (56 days of age), and were accordingly named A35, A56, B35 and B56. The results showed that, before weaning, the concentrations of acetic acid, propionic acid, butyric acid and total volatile fatty acids (TVFA) in group B35 were significantly higher than those in group A35 (p &lt; 0.05), while the concentrations of isobutyric acid, valeric acid and isovaleric acid were significantly lower than those in group A35 (p &lt; 0.05). After weaning, the concentrations of all volatile acids and total acids in group B56 were significantly lower than those in group A56 (p &lt; 0.01). At the phylum level, the dominant phyla identified were Firmicutes and Bacteroidetes; the relative abundances of Firmicutes and Desulfobacterota were significantly higher and lower in group B35 than in group A35, respectively (p &lt; 0.05); the relative abundances of Euryarchaeota and Desulfobacterota were significantly higher and lower in group A56 than in group A35 (p &lt; 0.05); and, at the genus level, the relative abundance of Lachnospiraceae_FCS020_group and Eubacterium nodatum group had higher relative abundance in group B35 before weaning (p &lt; 0.05). Metabolomic results showed that feeding 1.0 NDF/starch ratio starter before weaning significantly up-regulated (p &lt; 0.05) the concentrations of several anti-inflammatory-related metabolites such as lithocholic acid, oleanolic acid and LysoP. After weaning, the number of differential microorganisms and anti-inflammatory-related metabolites decreased between the two ratios. In summary, feeding a 1.0 NDF/starch ratio starter may be more effective in regulating microbial fermentation, leading to an increase in beneficial microbiota and metabolites, thus improving colonic environmental homeostasis in lambs before and after weaning.

Influence of Brown or Germinated Brown Rice Supplementation on Fecal Short-Chain Fatty Acids and Microbiome in Diet-Induced Insulin-Resistant Mice.

Intake of whole grain foods is associated with improving metabolic profile compared to refined grain products, but the underlying mechanism remains unclear. The present study examined the effects of brown rice (BRR) or germinated brown rice (GBR) supplementation on fecal short-chain fatty acids (SCFAs), and relationship with gut microbiota, metabolism and inflammation in high fat (HF)-diet-fed mice. The results demonstrated that an HF diet supplemented with BRR or GBR comparably increased the abundance of fecal isobutyric acid compared to that in mice receiving HF+white rice (WHR) diet (p < 0.01). The abundance of valeric acid in HF+GBR-diet-fed mice was higher than those receiving HF+WHR diet (p < 0.05). The abundances of fecal isobutyric acid negatively correlated with fasting plasma glucose, insulin, cholesterol, triglycerides, tumor necrosis factor-α, plasminogen activator inhibit-1, monocyte chemotactic protein-1 and homeostatic model assessment of insulin resistance (p < 0.01). The abundance of valeric acids negatively correlated with insulin resistance (p < 0.05). The abundances of isobutyric acid positively correlated with Lactobacillus, but negatively correlated with Dubosiella genus bacteria (p < 0.05). The findings demonstrated that the increases in SCFAs in the feces of BRR and GBR-treated mice were associated with improvements in gut microbiome, metabolic and inflammatory profile, which may contribute to the antidiabetic and anti-inflammatory effects of the whole grains in HF-diet-fed mice.

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.