Gas Chromatograph-time Of Flight Mass Spectrometer Research Articles

276 Effects of Monoglycerides on Serum Metabolomic Profiles in Weanling Pigs Experimentally Infected with a Pathogenic Escherichia Coli

Abstract Our previous research suggests that supplementation of monoglycerides may reduce diarrhea severity and intestinal and systemic inflammation in weaned pigs infected with Escherichia coli (E. coli) F18. The objective of this study was to investigate the effects of monoglycerides on serum metabolomic profiles of weaned pigs experimentally infected with E. coli F18. Sixty weaned pigs [body weight (BW) = 6.49 ± 0.74 kg; around 21 d old] were individually housed and fed with one of four diets (15 replicates/diet): 1) control diet (CON); 2) CON+0.3% monoglycerides; 3) CON+3,000 mg/kg ZnO and 4) CON+50 mg/kg antibiotics (carbadox). The experiment lasted 28 days with 7 days before and 21 days after the first inoculation [d 0 post-inoculation (PI)]. All piglets were orally challenged with F18 E. coli (1010 CFU/3 mL) for 3 consecutive days. Serum samples were collected on d 5 and 14 PI to analyze untargeted metabolomics by gas chromatography-time of flight-mass spectrometer (GC-TOF-MS). The metabolomics data were analyzed using different modules of a web-based platform, MetaboAnalyst 5.0. Statistical significance was declared at a false discovery rate q < 0.2 and fold change > 2.0. Pathway and metabolite set enrichment analysis were performed on identified metabolites that had a Variable Importance in Projection (VIP) score > 1. On d 5 PI, supplementation of high dose ZnO up-regulated (q < 0.2) pantothenic acid and fructose, compared with control. Supplementation of monoglycerides altered (q < 0.2) the relative abundances of 14 metabolites (7 up-regulated and 7 down-regulated) compared with high dose ZnO, and upregulated (q < 0.2) lactose and cellobiose compared with antibiotics. On d 14 PI, supplementation of high dose ZnO changed (q < 0.2) abundances of 10 metabolites (7 up-regulated and 3 down-regulated) compared with control. Supplementation of monoglycerides up-regulated (q < 0.2) hippuric acid and indole-3-propionic acid, and down-regulated (q < 0.2) 8 metabolites (including glutaric acid, serotonin, mannose, etc.) compared with the high dose ZnO. Citrate cycle, taurine and hypotaurine metabolism, and beta-alanine metabolism were the most (VIP > 1) affected pathways when monoglycerides were compared with high dose ZnO on d 5 PI. TCA cycle, glyoxylate and dicarboxylate metabolism, alanine, aspartate and glutamate metabolism, and pyrimidine metabolism were the most (VIP > 1) affected metabolic pathways when monoglycerides were compared with high dose ZnO on d 14 PI. Limited differential metabolites were identified when comparing control vs. monoglycerides on d 5 and 14 PI. In conclusion, consistent with performance, diarrhea, and systemic inflammation data, serum metabolomics results indicate that high dose of ZnO supplementation had stronger impacts on the host metabolism of E. coli infected pigs, compared with monoglycerides and antibiotics.

Nontargeted metabolomic analysis to unravel alleviation mechanisms of carbon nanotubes on inhibition of alfalfa growth under pyrene stress

Carbon nanotubes have displayed great potential in enhancing phytoremediation of PAHs polluted soils. However, the response of plants to the coexistence of carbon nanotubes and PAHs and the associated influencing mechanisms remain largely unknown. Here, the effect of carbon nanotubes on alfalfa growth and pyrene uptake under exposure to pyrene was evaluated through sand culture experiment and gas chromatography time-of-flight mass spectrometer (GC-TOF-MS) based metabolomics. Results showed that pyrene at 10 mg kg−1 obviously reduced the shoot fresh weight of alfalfa by 18.3 %. Multiwall carbon nanotubes (MWCNTs) at 25 and 50 mg kg−1 significantly enhanced the shoot fresh weight in a dose-dependent manner, nearly by 80 % at 50 mg kg−1. Pyrene was mainly accumulated in alfalfa roots, in which the concentration was 35 times as much as that in shoots. MWCNTs greatly enhanced the accumulation of pyrene in alfalfa roots, almost by two times at 50 mg kg−1, while decreased pyrene concentration in shoots, from 0.11 mg kg−1 to 0.044 mg kg−1 at MWCNTs concentration of 50 mg kg−1. Metabolomics data revealed that pyrene at 10 mg kg−1 trigged significant metabolic changes in alfalfa root exudates, downregulating 27 metabolites. MWCNTs generated an increase in the contents of some downregulated metabolites caused by pyrene stress, which were restored to the original level or even higher, mainly including organic acids and amino acids. MWNCTs significantly enriched some metabolic pathways positively correlated with shoot growth and pyrene accumulation in shoots under exposure to pyrene, including TCA cycle, glyoxylate and dicarboxylate metabolism, cysteine and methione metabolism as well as alanine, aspartate and glutamate metabolism. This work highlights the regulation effect of MWCNTs on the metabolism of root exudates, which are helpful for alfalfa to alleviate the stress from pyrene contamination.

Minimal Gluten Exposure Alters Urinary Volatile Organic Compounds in Stable Coeliac Disease.

Coeliac disease (CD) patients are distinguishable from healthy individuals via urinary volatile organic compounds (VOCs) analysis. We exposed 20 stable CD patients on gluten-free diet (GFDs) to a 14-day, 3 g/day gluten challenge (GCh), and assessed urinary VOC changes. A control cohort of 20 patients continued on GFD. Urine samples from Days 0, 7, 14, 28 and 56 were analysed using Lonestar FAIMS and Markes Gas Chromatography–Time of Flight–Mass Spectrometer (GC-TOF-MS). VOC signatures on D (day) 7–56 were compared with D0. Statistical analysis was performed using R. In GCh patients, FAIMS revealed significant VOC differences for all time points compared to D0. GC-TOF-MS revealed significant changes at D7 and D14 only. In control samples, FAIMS revealed significant differences at D7 only. GC-TOF-MS detected no significant differences. Chemical analysis via GC-MS-TOF revealed 12 chemicals with significantly altered intensities at D7 vs. D0 for GCh patients. The alterations persisted for six chemicals at D14 and one (N-methyltaurine) remained altered after D14. This low-dose, short-duration challenge was well tolerated. FAIMS and GC-TOF-MS detected VOC signature changes in CD patients when undergoing a minimal GCh. These findings suggest urinary VOCs could have a role in monitoring dietary compliance in CD patients.

PSVIII-7 Effects of Bacillus subtilis on colon digesta metabolomic profiles in weanling pigs experimentally infected with a pathogenic E. coli

Abstract Our previous studies have shown that supplementation of Bacillus subtilis enhanced growth rate, improved gut barrier function, and modified colon microbiome of weaned pigs infected with pathogenic Escherichia coli (E. coli). The objective of this experiment was to investigate the effects of Bacillus subtilis on colon digesta metabolomic profiles of weaned pigs experimentally infected with F18 E. coli. Forty-eight pigs (6.73 ± 0.77 kg BW) were individually housed in disease containment rooms and randomly allotted to one of the four treatments (12 pigs/treatment). Four treatments included negative control (NC), positive control (PC), low-dose (1.28 × 109 CFU Bacillus subtilis/kg feed), and high-dose (2.56 × 109 CFU Bacillus subtilis/kg feed). The experiment lasted 18 d [7 d before and 11 d after first inoculation (d 0)]. The F18 E. coli inoculum was orally provided to all pigs with the dose of 1010 cfu/3 mL for 3 consecutive days, except NC. Twenty-four pigs (6 pigs/treatment) were euthanized on d 5 post-inoculation (PI) and the remained pigs were euthanized on d 11 PI to collect colon digesta for the analysis of metabolomic profiles by gas chromatography time of flight-mass spectrometer (GCTOF-MS). All processed data were statistically analyzed and evaluated by online MetaboAnalyst tool. No significant differences were observed in the metabolites between NC and PC on d 5 and 11 PI. Compared with PC, low- and high-dose Bacillus subtilis reduced (Fold change > 1.5; FDR < 0.20) four metabolites (proline, 2-hydroxyglutaric acid, lysine, and glutamic acid) and two metabolites (ribose, and D-xylulose) in colon digesta on d 5 PI, respectively. These metabolites were related to aminoacyl-tRNA-biosynthesis, arginine and proline metabolism, and lysine degradation. In conclusion, supplementation of Bacillus subtilis modified the levels of microbial metabolites associated with amino acid metabolism in colon digesta of pigs.

PSVIII-2 Dietary supplementation of Bacillus subtilis altered metabolites in the intestine of weaned pigs

Abstract This experiment aimed to investigate the effects of dietary supplementation of Bacillus subtilis probiotics on metabolites in the intestines of weaned pigs experimentally infected with an enterotoxigenic Escherichia coli (E. coli). Forty-eight weaned pigs (6.17 ± 0.36 kg BW) were individually housed in disease containment rooms and randomly allotted to one of four dietary treatments: negative control (NC, control diet without E. coli challenge), positive control (PC, control diet with E. coli challenge), and supplementation of 50 mg/kg of carbadox or 500 mg/kg of Bacillus subtilis probiotics. The experiment lasted 28 days with 7 days before and 21 days after the first E. coli inoculation. The F18 E. coli were given to pigs at 1010 CFU/3 mL dose for three consecutive days. At the end of the experiment, all pigs were euthanized to collect ileal mucosa and colon digesta for the analysis of metabolomic profiles by gas chromatography time of flight-mass spectrometer (GCTOF-MS). All data were analyzed by an online MetaboAnalyst tool (https://www.metaboanalyst.ca/). Statistical significance was declared at P < 0.05 and the false discovery rate–adjusted P value (q value) < 0.20. A total of 282 (141 identified and 121 unidentified) and 196 (127 identified and 69 unidentified) metabolites were detected in ileal mucosa and colon digesta, respectively. Forty-nine identified metabolites in ileal mucosa significantly differed among experimental groups (P < 0.05; q < 0.20). The most impacted metabolic pathways were galactose metabolism, aspartate and glutamate metabolism, fructose and mannose degradation, pentose phosphate pathway, and urea cycle. However, in colon digesta, only 7 identified metabolites differed among experimental groups (P < 0.05; q < 0.20) and the majority of them were involved in purine metabolism. Results of metabolomics indicated that supplementation of Bacillus subtilis or antibiotics altered metabolites in the intestines of weaned pigs. In particular, more treatment impacts were observed in the metabolite profiles in ileal mucosa compared with colon digesta.

Application of sensory evaluation, GC-ToF-MS, and E-nose to discriminate the flavor differences among five distinct parts of the Chinese blanched chicken

Blanched chicken, boiling the whole chicken without removing head and butt parts during process, is a traditional poultry product in China. In this manuscript, the flavor differences of five parts (skin, breast, thigh, head and butt) of the Chinese blanched chicken (CBC) were studied using sensory evaluation and instrumental analysis. Check-all-that-apply (CATA), rate-all-that-apply (RATA), and 9-point hedonic preference were used to collect consumers’ sensory results. Gas chromatograph-time of flight mass spectrometer (GC-ToF-MS) and electronic nose (E-nose) were used to discriminate flavor variances. CATA perceptions showed different parts of CBC stimulated consumers’ odor and emotion feelings differently. GC-ToF-MS and E-nose data elaborated that the flavor of breast with chicken-like flavor was better than the other parts. Consumers preferred the chicken breast part the most. This analysis of different parts of CBC could provide advice to cater consumers’ preference and predict the quality change might induce.

PSII-13 Effects of antibiotics on serum metabolomic profiles in weanling pigs experimentally infected with a pathogenic E. coli

Abstract Our previous studies have shown that exposure to low-dose antibiotic growth promoter (AGP) may exacerbate the negative effects of Escherichia coli (E. coli) infection on weaned pigs. The objective of this experiment was to investigate the effects of low-dose AGP on serum metabolomic profiles of weaned pigs experimentally infected with F18 E. coli. Thirty-four pigs (6.88 ± 1.03 kg BW) were individually housed in disease containment rooms and randomly allotted to one of three treatments with 9–13 replicate pigs per treatment. The three dietary treatments were control diet (control) and 2 additional diets supplemented with 0.5 or 50 mg/kg of AGP (carbadox), respectively. The experiment lasted 18 d [7 d before and 11 d after first inoculation (d 0)]. The F18 E. coli inoculum was orally provided to all pigs with the dose of 1010 cfu/3 mL for 3 consecutive days. Blood samples were collected on d 0 before E. coli inoculation and on d 5 and 11 post-inoculation (PI). Serum metabolomics were analyzed for untargeted metabolomics by gas chromatography-time of flight-mass spectrometer (GC-TOF-MS). All processed data were statistically analyzed and evaluated by online MetaboAnalyst tool. No significant differences were observed in serum metabolites between control and low-dose AGP throughout the experiment. Supplementation of high-dose AGP changed the concentrations of several serum metabolites (P < 0.05; arabitol, guanine, and xylitol) compared with control pigs on d 5 PI. Further metabolic pathway enrichment analysis showed that low-dose AGP modified (P < 0.05) pentose phosphate pathway, DNA synthesis in T and B lymphocytes, bile acid metabolism, and amino acid metabolism in E. coli infected pigs, compared with high-dose AGP. In conclusion, the modification of serum metabolites and metabolic pathways by low-dose AGP may be involved in reduced growth performance, exacerbated diarrhea and systemic inflammation of weaned pigs induced by E. coli infection.

Microbiome-Metabolomics Analysis Investigating the Impacts of Dietary Starch Types on the Composition and Metabolism of Colonic Microbiota in Finishing Pigs.

The present study used a combination of 16S rRNA MiSeq sequencing strategy and gas chromatograph time of flight mass spectrometer (GC-TOF/MS) technique to investigate the effects of starch sources on the colonic microbiota and their metabolites in finishing pigs. A total of 72 crossbred barrows were allocated to three different experimental diets with eight replicates and three pigs per replicate. The diet types included tapioca starch (TS), corn starch (CS), and pea starch (PS) (amylose/amylopectin were 0.11, 0.25, and 0.44, respectively). Results showed that the PS diet markedly increased (adjusted P < 0.05) the abundance of short-chain fatty acids (SCFAs) and lactate producers, such as Lactobacillus, Prevotella, Faecalibacterium, and Megasphaera, while decreased (adjusted P < 0.05) the abundance of Escherichia coli when compared with the TS diet. The metabolomic and biochemistry analyses demonstrated that the PS diet increased (adjusted P < 0.05) the concentrations of organic acids (acetate, propionate, butyrate, valerate, and lactate) and some macronutrients (sugars and long-chain fatty acids), and decreased (adjusted P < 0.05) the amino acids and their derivatives (leucine, glycine, putrescine, cadaverine, skatole, indole, and phenol) when compared with the TS diet. Additionally, Spearman’s correlation analysis revealed that the changes in the colonic metabolites were associated with changes in the microbial composition. Correlatively, these findings demonstrated that the different dietary starch types treatment significantly altered the intestinal microbiota and metabolite profiles of the pigs, and dietary with higher amylose may offer potential benefits for gut health.

Compositional characterization of neutral fractions in

The neutral fractions of <300 °C fractions of six Chinese shale oils obtained from different locations of Huadian, Wangqing, Fushun, Longkou, Maoming and Yaojie were eluted to six sub-fractions using extrography method. The compositions of sub-fractions were determined using gas chromatography-time of flight mass spectrometer (GC-TOF/MS). The results showed that F1 sub-fractions contained aliphatic hydrocarbons, such as alkanes, alkenes and cycloalkanes. In addition, HD F1 sub-fraction had the highest content of aliphatic hydrocarbons. The F2 sub-fractions contained aromatic hydrocarbons with 1–4-ring. Furthermore, a small amount of heteroatom compounds with aromatic rings (such as, dibenzofurans and carbazols) were also detected. The F3 sub-fractions contained aliphatic ketones and aliphatic nitriles ranging from C7-C25 and C9-C24, respectively. The F4 sub-fractions contained aliphatic ketones. However, the aliphatic ketones in F3 sub-fractions were 4-, 5-, 6-, 7- and 9-ketones, whereas those in F4 sub-fractions were all 2-ketones. The F5 sub-fractions contained nine kinds of compounds. Moreover, 2,5-hexanedione was dominant in all the samples except for MM F5 sub-fraction, whereas only two compounds were detected in MM F5 sub-fraction. Moreover, the F6 sub-fractions with less than 1 wt% in neutral fractions contained the unresolved complex matter (UCM), which cannot be eluted through gas chromatography (GC). Compared with the distribution of compounds in sub-fractions, the compounds of different samples consisted of similar species and slightly different contents. It indicates that the formation of compounds in the neutral fraction follows the same reaction pathways during kerogen pyrolysis.

Fatty Acid Composition of Dried Fruits of Sclerocarya birrea, Diospyros blancoi and Landolphia kirkii.

Wild fruits are commonly consumed in the rural communities of South Africa. The information on their nutritionally important fatty acids is, however, limited. Three wild fruit species, Diospyros blancoi, Landolphia kirkii and Sclerocarya birrea from Limpopo Province were selected for evaluation of fatty acid content. Fatty acids composition of dried fruits of Diospyros blancoi (Db), Landolphia kirkii (Lk) and ripe and/or overripe Sclerocarya birrea (Sb) were evaluated by a gas chromatography-time of flight-mass spectrometer (GC-TOF-MS). Hexadecanoic acid (C16:0) was found in highest abundance in L. kirkii (57.73–73.55%), followed by S. birrea (55.92–71.31%) and D. blancoi (46.31–62.05%), respectively. Octadecanoic acid (C18:0) was of second highest abundance, with 24.71–100% in D. blancoi, L. kirkii (31.03–41.60%) and S. birrea (9.11–17.0%). The 9-octadecenoic acid (C18:1n-9) was the major unsaturated fatty acid in both S. birrea (5.33–18.82%), D. blancoi (8.22–8.92%), and L. kirkii (3.84–8.63%). The 9,-12-octadecadienoic acid (C18:2n-6) was the major unsaturated fatty acid in D. blancoi (22.34%). The 9,-12,-15-octadecatrienoic acid (C18:3n-3) was found in L. kirkii (3.51%) and S. birrea (2.79%). From the results, saturated fatty acids were the most dominant, whereas mono- and poly-unsaturated fatty acids were the minor constituents. Therefore, presence of nutritionally important essential fatty acids from S. birrea, D. blancoi and L. kirkii has been shown.

小鼠血清中内源性代谢物的GC/TOF-MS分析

A gas chromatography/time of flight-mass spectrometer (GC/TOF-MS) method of metabonomic analysis for small mouse serum was established. With optimizing derivatization, 269 peaks of GC/TOF-MS chromatogram were detected. Among them, 46 peaks with the similarity over 800 were identified for endogenous metabolites.18 endogenous metabolites were selected randomly to evaluate the precision and stability of the method, and 14 mixture standard of amino acids were selected for quantitative analysis. The results showed that linearities of the 14 mixture standards were good over the range of 2.78-113.20 ng/μL, precision for intra-day and inter-day tests were satisfying, and the precision values were all below 15% for 18 endogenous metabolites. Since trimethyl-silyl (TMS) derivatization of monosaccharides often results in the formation of multiple peaks, oximation can resolve the problem smoothly. The results suggest that the method could be usefully applied to metabolomic studies, by data processing, biological markers can be identified and a new way can be presented for disease diagnosis.

T2026 A Dietary Intervention With Arabinoxylan Oligosaccharides Reduces Colonic Protein Fermentation in Healthy Subjects: Results From Faecal Metabolite Fingerprint Analysis

Background The addition of prebiotics to the diet may improve host health by modulation of the colonicmetabolism. The effect of a new candidate prebiotic, arabinoxylan oligosaccharides (AXOS), on the colonic metabolism was evaluated by characterization of the metabolite profile in faeces. Methods AXOS was administered for 3 weeks at 10 g/day to 20 healthy volunteers (30% male; age 23(20-45); BMI 21(18-26)). Faecal samples were collected before and after the intervention with AXOS. To determine a broad range of fermentation metabolites, metabolic fingerprinting was applied using a purge-and-trap system coupled on-line to a gas chromatograph time-of-flight mass spectrometer (GC-TOF-MS). Cluster analysis, based on relative indices of all identified volatile organic compounds (VOCs) versus 2ethylbutyric acid as internal standard, was used to compare the metabolite profiles. Results A total of 179 different VOCs were identified in the faecal samples, 24 VOCs were present in more than 70% of the samples. The compounds acetaldehyde, butanoic acid, dimethyl disulfide, dimethyl trisulphide and limonene were present in all samples. Cluster analysis of the VOC fingerprints allowed to discriminate baseline samples from the samples after the intervention with AXOS, suggesting that the impact of the intervention exceeded the interindividual variability (Figure). This discrimination was mainly due to protein fermentation metabolites such as p-cresol, branched-chain fatty acids (4-methyl pentanoic acid, 2-methyl propanoic acid and 3methyl butanoic acid) and sulphur containing compounds (hydrogen sulphide, carbon disulfide, dimethyl tetrasulfide). Faecal short-chain fatty acids did not contribute to discrimination between both groups, although this does not preclude an increased SCFA production in the proximal colon. Conclusion Dietary intervention with AXOS has a considerable impact on the colonic metabolism mainly by decreasing proteolytic activity.

T2027 Lactobacillus casei Dn-114 Oo1 Strain in the Prevention of Postoperative Recurrence of Crohn's Disease: A Randomised, Double-Blind Placebo-Controlled Trial

Background The addition of prebiotics to the diet may improve host health by modulation of the colonicmetabolism. The effect of a new candidate prebiotic, arabinoxylan oligosaccharides (AXOS), on the colonic metabolism was evaluated by characterization of the metabolite profile in faeces. Methods AXOS was administered for 3 weeks at 10 g/day to 20 healthy volunteers (30% male; age 23(20-45); BMI 21(18-26)). Faecal samples were collected before and after the intervention with AXOS. To determine a broad range of fermentation metabolites, metabolic fingerprinting was applied using a purge-and-trap system coupled on-line to a gas chromatograph time-of-flight mass spectrometer (GC-TOF-MS). Cluster analysis, based on relative indices of all identified volatile organic compounds (VOCs) versus 2ethylbutyric acid as internal standard, was used to compare the metabolite profiles. Results A total of 179 different VOCs were identified in the faecal samples, 24 VOCs were present in more than 70% of the samples. The compounds acetaldehyde, butanoic acid, dimethyl disulfide, dimethyl trisulphide and limonene were present in all samples. Cluster analysis of the VOC fingerprints allowed to discriminate baseline samples from the samples after the intervention with AXOS, suggesting that the impact of the intervention exceeded the interindividual variability (Figure). This discrimination was mainly due to protein fermentation metabolites such as p-cresol, branched-chain fatty acids (4-methyl pentanoic acid, 2-methyl propanoic acid and 3methyl butanoic acid) and sulphur containing compounds (hydrogen sulphide, carbon disulfide, dimethyl tetrasulfide). Faecal short-chain fatty acids did not contribute to discrimination between both groups, although this does not preclude an increased SCFA production in the proximal colon. Conclusion Dietary intervention with AXOS has a considerable impact on the colonic metabolism mainly by decreasing proteolytic activity.

Field-portable, high-speed GC/TOFMS

This work is focused on developing a fast gas chromatograph, time-of-flight mass spectrometer (GC/TOFMS) for man-portable field use. The goal is to achieve a total system solution for meeting performance, size, weight, power, cost, and ruggedness requirements for a laboratory in the field. The core technology will also be adaptable to specific applications including real-time point detection for hazardous chemical releases (e.g., chemical weapons), for biological agent signature identification, and for mobile monitoring platforms (e.g., air, ship, truck). Previously we presented results of a feasibility demonstration for a 30-lb field-portable TOFMS system. In this work we present recent progress in integrating a low-power, high-speed GC and show the capability for accurately recording fast GC transients for targeted compound detection using a quadrupole ion trap, time-of-flight instrument (QitTof).