Human Fecal Flora Research Articles

MO1024CLOSTRIDIUM SEPTICUM INFECTION COMPLICATING HEMOLYTIC UREMIC SYNDROME: A CASE REPORT AND LITERATURE REVIEW

Abstract Background and Aims C.septicum is an anaerobic bacterium that resides in the gastrointestinal tract of herbivores. Its presence in human fecal flora is still debated, being found in only 2.8% of healthy adults. Transmitted by oral-fecal route, it reaches the systemic circulation, causing bacteremia, myonecrosis, bowel necrosis, intracranial abscesses/encephalitis. Shiga-toxin producing E. Coli related hemolytic uremic syndrome (STEC-HUS) is a thrombotic microangiopathy characterized by hemolytic anemia, thrombocytopenia and kidney damage, related to STEC infection. Severe presentation includes gastrointestinal and neurologic involvement. Microangiopathic lesions in the colonic mucosa can facilitate the colonization of systemic circulation by C.septicum, spreading the superinfection. Since the first report in 1988, very few cases of STEC-HUS complicated by C.septicum superinfection have been described in literature and thus the factors predicting clinical outcome are not clear. Method We describe the case of a 5-years-old girl admitted for anemia, AKI, thrombocytopenia and diarrhea. Previous history was unremarkable. STEC-HUS diagnosis was made. Despite prompt conservative treatment, 12h later her clinical condition worsened, showing ESKD needing dialysis, abdominal pain, progressive hyporesponsiveness. The brain CT scan showed pneumocephalus and encephalitis; blood cultures were drawn and broad-spectrum antibiotic therapy was set (Tab.1). Cardiovascular instability prevented surgical treatment of pneumocephalus to be done. The patient died shortly after because of septic shock. Post-mortem stool and blood cultures confirmed STEC infection complicated by C.Septicum. Previous literature on this specific clinical picture has been reviewed and summarized. Results Eleven additional cases (7 males) have been previously described. Mean age of presentation was 2.9 years. A; abdominal symptoms (commonly distention and pain) were reported in all cases, while ESRD was present in 10 cases. Six patients presented fever. Central nervous system presentation as pneumocephalus was associated with poor prognosis, while surgical treatment availability of brain lesions to survival. In one case the infection caused myonecrosis (Tab. 1). The mortality rate was about 60%. In 7 cases, clinical conditions worsened in less than 24h and this was in all cases related to poor outcome. Conclusion C.septicum superinfection complicating STEC-HUS is a rare but fearsome complication to be aware of. Rapid diagnosis and surgical treatment are essential for the successful management of this particular condition.

Effects of Cyanidin-3-Glucoside Derived from Black Rice (Oryza Sativa L.) and Enzymatically Acylated Cyanidin-3-Glucoside Lauryl Ester on Intestinal Microorganisms In Vitro

In this paper, cyanidin-3-glucoside was isolated and purified from black rice, then enzymatic acylation with lauric acid to obtain cyanidin-3-glucoside lauryl ester. The structure of cyanidin-3-glucoside lauryl ester was characterized by liquid chromatography electrospray ionization tandem mass spectrometry and Fourier transform infrared spectroscopy. Then the potential proliferative effect on probiotics and inhibitory effect on harmful bacteria of cyanidin-3-glucoside and cyanidin-3-glucoside lauryl ester were studied in vitro. The effects of cyanidin-3-glucoside and cyanidin-3-glucoside lauryl ester on the composition of human fecal intestinal flora and its metabolic pathway were also analyzed through 16S ribosomal ribonucleic acid high-throughput sequencing and gas chromatography-mass spectroscopy, respectively. The results indicated that cyanidin-3-glucoside lauryl ester was better than cyanidin-3-glucoside in promoting the growth of B. adolescentis, B. infantis, L. thermophiles, and L. acidophilus as well as inhibiting the growth of S. dysenteriae, Y. enterocolitica, S. enteritidis, and S. typhi. Additionally, the proliferative effect of cyanidin-3-glucoside lauryl ester was significantly improved in a lower media pH due to the intestinal microbial metabolism to produce more organic acids, such as propionic acid, phenyllactic acid, and lauric acid. The study will provide a theoretical basis for the application of cyanidin-3-glucoside lauryl ester in the intestinal health.

Effect of xylitol on gut microbiota in an in vitro colonic simulation

Abstract Objective Xylitol has been commonly used as a sweetener and dental caries protective agent. However, how xylitol influences the composition and metabolism of gut microbiota is not known yet. This study aimed to dissect the changes of microbiota and their metabolites under xylitol supplementation in an in vitro colonic simulation. Materials and methods A single-phase continuous fermentation model was used to culture human fecal flora and the 16s rDNA and short chain fatty acid were analyzed. Results and discussion It was found that gut microbiota composition differentiated after xylitol supplementation only for the beginning 3 days. Xylitol significantly enhanced the relative amount of butyrate synthesizing bacteria such as Clostridium and Phascolarctobacterium. Meanwhile, xylitol increased the production of propionic acid and butyrate. An increase of Escherichia population sizes after xylitol supplementation was beyond expectation. By Spearman analysis, a positive relationship between Escherichia and Bifidobacterium was found. Conclusion xylitol can rapidly enhance the total amount of short chain fatty acids, but its influence will disappear after 3 days of fermentation. Results of this investigation can be a guideline for the further investigations on xylitol in relation to gut microbiota and the daily intake determinations.

Ultra-performance liquid chromatography/quadrupole time-of-flight mass spectrometry analysis of In vitro metabolites of lignans from fructus forsythiae by Human Fecal Flora

Background: Phillyrin and (+)-pinoresinol 4-O-β-D-glucoside are the major active furofuran-type lignans in Fructus Forsythiae. The metabolic routes and metabolites of these two lignans are not well understood yet. Objective: In this study, we attempted to identify the human-intestine bacterial metabolites of lignans from Fructus Forsythiae. Materials and Methods: Two natural compounds, phillyrin and (+)-pinoresinol 4-O-β-D-glucoside were incubated with human fecal microflora in an anaerobic incubator for 72 h and the metabolites with highly sensitive ultra-performance liquid chromatography/quadrupole time-of-flight mass spectrometry (UPLC-Q-TOF/MS) were analyzed. Results: As a result, nine metabolites were determined using a Syncronis™ C18column (particle size 1.7 mm) in a gradient elution system. These metabolites were then identified according to the mass fragmental mechanism, MS/MS fragment ions, and previous publications. The results of this study indicated that the major metabolites of furofuran-type lignans are through the processes of hydrolysis, demethylation, reduction, dehydroxylation, and oxidation. Conclusions: Lignans can be metabolized by intestinal microbiota and the intestinal bacteria play a critical role in the metabolism of components administered orally. Abbreviations used: GAM: General anaerobic medium; UPLC/Q-TOF-MS: Ultra-performance liquid chromatography/quadrupole-time-of-flight mass spectrometry; ESI: Negative ion electrospray; RT: Retention time; TCM: Traditional Chinese Medicine.

Effects of different carbohydrates on the simulation of human intestinal bacterial flora with in vitro culture

To investigate the optimal growth condition of human fecal bacterial flora in vitro by comparing the effect of different carbohydrates as cultural media. Three fecal samples (1, 2, 3) were collected and inoculated into a single-stage chemostat system, in which starch medium (VI) and starch polysaccharide medium(XP) were used. Samples were collected for bacterial genomic DNA extraction and polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE) analysis. Bacterial composition and short chain fatty acid (SCFA) were then analyzed. The single stage chemostat system reached steady after operating 8 days, when evaluated by the PCR-DGGE. Bacterial 16s rRNA high-throughput sequencing showed that the intestinal bacteria of these three volunteers was mainly composed of four bacterial phyla, namely, Bacteroidetes, Firmicutes, Proteobacteria and Actinobacteria. When the influence of bacterial abundance was considered, the similarity of bacterial composition between the original fecal samples to the harvested flora after culture was 0.847, 0.825, 0.968 in VI medium and 0.927, 0.926, 0.836 in XP medium, respectively. The similarity was decreased to 0.553, 0.580, 0.623 with VI medium and 0.617, 0.520, 0.574 with XP medium, when the number of bacterial species was considered. The variation of host individual also influenced the simulation. VI medium favored fecal sample 3, while XP medium more benefited sample 1 and 2. Bacteroides and Lachnospiraceae_incertae_sedis grew in both VI and XP medium. However, some species were only detected in VI medium and some were specifically found in the XP medium. The SCFA concentration in fermenters was 15-35 mmol/L, mainly propionate and butyrate. The chemostat system works for stimulating human gut bacterial flora in vitro. The bacterial composition is affected by different carbohydrate in the culture medium yet with close simulation higher than 80%.

Killing of VRE Enterococcus faecalis by commensal strains: Evidence for evolution and accumulation of mobile elements in the absence of competition

ABSTRACTEnterococci are members of the gastrointestinal tract of humans and most animals that, over the past 3 decades, have emerged as leading causes of multidrug resistant hospital acquired infection (HAI). In addition to their general hardiness, many traits have entered enterococcal lineages through horizontal gene transfer, which has led to the evolution of pathogenic hospital-associated lineages uniquely adapted for survival and proliferation in the antibiotic perturbed ecology of the gastrointestinal tract. We recently observed that the accretion of mobile genetic elements in the prototype vancomycin resistant E. faecalis, clinical isolate V583, renders it unable to co-exist with native enterococci in healthy human fecal flora. In this addendum, we discuss how these findings inform our understanding of how multidrug resistant enterococci evolve, and the implications for the development of treatments that limit colonization and spread of highly antibiotic refractory microbes of this type.

Fluoroquinolones and qnr genes in sediment, water, soil, and human fecal flora in an environment polluted by manufacturing discharges.

There is increasing concern that environmental antibiotic pollution promotes transfer of resistance genes to the human microbiota. Here, fluoroquinolone-polluted river sediment, well water, irrigated farmland, and human fecal flora of local villagers within a pharmaceutical industrial region in India were analyzed for quinolone resistance (qnr) genes by quantitative PCR. Similar samples from Indian villages farther away from industrial areas, as well as fecal samples from Swedish study participants and river sediment from Sweden, were included for comparison. Fluoroquinolones were detected by MS/MS in well water and soil from all villages located within three km from industrially polluted waterways. Quinolone resistance genes were detected in 42% of well water, 7% of soil samples and in 100% and 18% of Indian and Swedish river sediments, respectively. High antibiotic concentrations in Indian sediment coincided with high abundances of qnr, whereas lower fluoroquinolone levels in well water and soil did not. We could not find support for an enrichment of qnr in fecal samples from people living in the fluoroquinolone-contaminated villages. However, as qnr was detected in 91% of all Indian fecal samples (24% of the Swedish) it suggests that the spread of qnr between people is currently a dominating transmission route.

Fecal carriage of extended-spectrum β-lactamases and AmpC-producing Escherichia coli in a Libyan community.

BackgroundExtended-spectrum β-lactamases (ESBLs), including the AmpC type, are important mechanisms of resistance among Enterobacteriaeceae. CTX-M type extended-spectrum β- lactamases, of which there are now over 90 variants, are distributed globally, yet appear to vary in regional distribution. AmpC β-lactamases hydrolyze third generation cephalosporins, but are resistant to inhibition by clavulanate or other β-lactamase inhibitors in vitro. Fecal carriage and rates of colonization by bacteria harboring these resistance mechanisms have been reported in patients with community-acquired infections and in healthy members of their households. Expression of these ESBLs compromises the efficacy of current antibacterial therapies, potentially increasing the seriousness of hospital- and community-acquired Escherichia coli (E. coli) infections.To investigate the occurrence of ESBL-producing E. coli in human fecal flora isolated from two pediatric populations residing in the Libyan cities Zleiten and Abou El Khoms. Isolates were further studied to characterize genes encoding β-lactam resistance, and establish genetic relationships.MethodsAntibiotic resistance profiles of phenotypically characterized E. coli isolates recovered from the stools of 243 Libyan children during two surveillance periods in 2001 and 2007 were determined by the disk diffusion method. ESBL-screening was performed using the cephalosporin/clavulanate double synergy disc method, and the AmpC-phenotype was confirmed by the aminophenyl-boronic acid test. ESBL genes were molecularly characterized. Phylogenetic group and multilocus sequence typing (MLST) were determined for ESBL-producing isolates and PFGE was performed to compare banding profiles of some dominant strains.ResultsESBLs were identified in 13.4% (18/134) of E. coli isolates, and nine isolates (6.7%) demonstrated AmpC activity; all 18 isolates contained a CTX-M gene. Three CTX-M gene families (CTX-M-1, n = 9; CTX-M-15, n = 8 and CTX-M-3, n = 1) were distributed in diverse E. coli backgrounds (phylogenetic group D, 39%; B2, 28%; B1, 22% and A, 11%). MLST analysis revealed 14 sequence type (ST) with six new sequence types. The gene encoding the CMY-2 enzyme was detected in five AmpC-positive E. coli.ConclusionsThese results identified heterogeneous clones of CTX-M-producing E. coli in the fecal isolates, indicating that the intestinal tract acts as a reservoir for ESBL-producing organisms, and a trafficker of antibiotic resistance genes.

Evaluation of an Oral Subchronic Exposure of Deoxynivalenol on the Composition of Human Gut Microbiota in a Model of Human Microbiota-Associated Rats

BackgroundDeoxynivalenol (DON), a mycotoxin produced by Fusarium species, is one of the most prevalent mycotoxins present in cereal crops worldwide. Due to its toxic properties, high stability and prevalence, the presence of DON in the food chain represents a health risk for both humans and animals. The gastrointestinal microbiota represents potentially the first target for these food contaminants. Thus, the effects of mycotoxins on the human gut microbiota is clearly an issue that needs to be addressed in further detail. Using a human microbiota-associated rat model, the aim of the present study was to evaluate the impact of a chronic exposure of DON on the composition of human gut microbiota.Methodology/Principal FindingsFour groups of 5 germ free male rats each, housed in 4 sterile isolators, were inoculated with a different fresh human fecal flora. Rats were then fed daily by gavage with a solution of DON at 100 µg/kg bw for 4 weeks. Fecal samples were collected at day 0 before the beginning of the treatment; days 7, 16, 21, and 27 during the treatment; and 10 days after the end of the treatment at day 37. DON effect was assessed by real-time PCR quantification of dominant and subdominant bacterial groups in feces. Despite a different intestinal microbiota in each isolator, similar trends were generally observed. During oral DON exposure, a significant increase of 0.5 log10 was observed for the Bacteroides/Prevotella group during the first 3 weeks of administration. Concentration levels for Escherichia coli decreased at day 27. This significant decrease (0.9 log10 CFU/g) remained stable until the end of the experiment.Conclusions/SignificanceWe have demonstrated an impact of oral DON exposure on the human gut microbiota composition. These findings can serve as a template for risk assessment studies of food contaminants on the human gut microbiota.

Impact of cyadox on human colonic microflora in chemostat models

The aim of this study was to evaluate the microbiological safety of cyadox, a new member of quinoxaline-1,4-dioxides (QdNOs), on human intestinal flora. Four chemostats containing human fecal flora were exposed to 0, 16, 32, and 128μg/mL of cyadox, respectively. Bacterial populations, resistance rates of two predominant bacteria and short-chain fatty acids (SCFA) were monitored daily prior to and during drug MOA Laboratory of Risk Assessment for Quality and Safety of Livestock and Poultry Products exposure. Colonization resistance (CR) of each community was determined by three successive daily challenges of Salmonella typhimurium. Efflux pump gene (oqxAB) in the Escherichia coli and Enterococcus strains were analyzed by PCR amplification and DNA sequencing. No change in SCFA was observed after exposure to different concentrations of cyadox. Lower concentration of cyadox (16μg/mL) had no adverse effect on human microflora. However, higher concentrations of cyadox (32 and 128μg/mL) could change bacterial population and increase the proportion of resistant E. coli and Enterococcus. More than 26% (12/46) of cyadox resistant E. coli strains contained oqxAB gene, while all the resistant Enterococcus were negative to oqxAB gene. Relationship between the occurrence of oqxAB gene and cyadox exposure is inconclusive. Our data indicated that 16μg/mL might be the no observed effect concentration (NOEC) of cyadox. Derived microbiological acceptable daily intake (mADI) would be 1552.03μg/kgd. The data obtained in present study indicated that cyadox was a safe member of QdNOs family of antimicrobial agents.

UPLC-Q-TOF/MS for Analysis of the Metabolites of Flavone Glycosides from Scutellaria baicalensis Georgi by Human Fecal Flora in Vitro

The active ingredients of Scutellaria baicalensis Georgi, a valuable traditional Chinese medicine, are polyhydroxyflavones, namely baicalin, scutellarin and wogonoside. However, information about the metabolic routes, metabolites and even more the effect of chemical structure on the stability of the three has been limited. In this article, the three natural compounds were incubated with human fecal flora, respectively, and highly sensitive and specific ultra-performance liquid chromatography/quadrupole time-of-flight mass spectrometry implementing the MetaboLynx™ software method was used for the drug metabolism study. The chromatographic separation was performed on a 1.7-μm particle size Syncronis C18 column using a gradient elution system. The components in the extract were identified and confirmed according to the mass spectrometric fragmentation mechanisms, MS/MS fragment ions and relevant literature by means of electrospray ionization mass spectrometry in negative ion mode. With this method, a total of ten metabolites were identified based on MS and MS/MS data. The results indicated that hydrogenation, methylation and deglycosylation were the major metabolic pathways of the three flavone glycosides in vitro, and the metabolic stability was closely related to the chemical structure. This study will be helpful for fully understanding the impact of intestinal bacteria on these active components. Furthermore, this work demonstrated the potential of the ultra-performance liquid chromatography/quadrupole time-of-flight mass spectrometry approach with MetaboLynx for quite rapid, simple, reliable and automated identification of metabolites of natural products.

Air, Water, and Surface Bacterial Contamination in a University‐Hospital Autopsy Room*

Today, little is known about the bacteriological environment of the autopsy room and its potential interest for medico-legal practices. Seven hundred fifty microbiological samples were taken from surface (n = 660), air (n = 48), and water (n = 42) to evaluate it in a French University Forensic Department. Median bacterial counts were compared before and during autopsy for air samples, and before and after autopsy for surface samples, using Wilcoxon matched pairs signed ranks test. Bacterial identification relied on traditional phenotypic methods. Bacterial counts in the air were low before autopsy, increased significantly during procedure, and seemed more linked to the number of people in the room than to an important production of aerosol-containing bacteria. Despite cleaning, human fecal flora was omnipresent on surfaces, which revealed insufficient disinfection. Bacteriological sampling is an easy way to monitor cleaning practices in postmortem rooms, but chiefly a way to improve the reliability of medico-legal proofs of infectious deaths.

Investigation of Micro-Particles Produced from Wheat Bran and Sugarcane Bagasse Fermentation by Human Faecal Flora and the Binding Capacities of Fermentation Residues

Wheat bran has been consistently reported to protect against colon cancer. To investigate the mechanism of the unique characteristics of wheat bran, the morphology and zeta potential of micro-particles released from wheat bran and sugarcane bagasse fermentation by human faecal flora were studied by atomic force microscopy and laser light scattering technique, respectively. Microparticles released from wheat bran fermentation differed significantly from those produced from sugarcane bagasse fermentation in shape, size (237 VS 454 nm), and zeta potential (-20.01 VS -3.96 mv). Scanning electron microscopic observations showed that the structure of fermented residue of wheat bran was more loose and porous than that of sugarcane bagasse, and had a larger surface area. In vitro studies revealed higher binding capacities of fermented wheat bran for bile acid, cholesterol, and peanut oil compared with fermented sugarcane bagasse.

Effects of enrofloxacin on the human intestinal microbiota in vitro

An anaerobic, continuous-flow culture method has been developed to assess the effects of different levels of enrofloxacin (ENR) on the human intestinal microbiota. Chemostats containing human faecal flora were exposed to 1.25, 12.5 and 125 μg/mL ENR. Before and during drug exposure, samples aspirated from culture vessels were analysed using viable cell counting and denaturing gradient gel electrophoresis (DGGE). In addition, the colonisation resistance (CR) of the microbiota to Candida albicans SC5314 was evaluated. When exposed to 1.25 μg/mL ENR, total counts of aerobic bacteria, anaerobic bacteria, Lactobacillus, enterococci, Escherichia coli and Bacteroides fragilis were similar to the control group, except for Bifidobacterium; when exposed to 12.5 μg/mL and 125 μg/mL ENR, numbers of categorised microorganisms changed significantly, except for B. fragilis. DGGE indicated that although 1.25 μg/mL ENR had little effect on the total number of microbiota, several bands representing dominant bacteria disappeared. The bands disappeared more quickly when exposed to 12.5 μg/mL and 125 μg/mL ENR. In addition to their influence on microbial diversity, different levels of ENR reduced the CR of the intestinal microbiota to C. albicans SC5314.

Molecular Weight of β‐Glucan Affects Physical Characteristics, In Vitro Bile Acid Binding, and Fermentation of Muffins

ABSTRACTMuffins containing different amounts and molecular weights (MW) of β‐glucan were evaluated for the effect of β‐glucan on the physical characteristics of the muffins and on in vitro bile acid binding and fermentation with human fecal flora. Wheat flour muffins were prepared with the addition of β‐glucan extracts with high‐, medium‐, or low‐MW. For oat flour muffins, the native oat flour contained high‐MW β‐glucan; the oat flours were treated to create medium‐ and low‐MW β‐glucan within the prepared muffin treatments. For each 60‐g muffin, the amounts of β‐glucan were 0.52, 0.57, and 0.59 g for high‐, medium‐, and low‐MW β‐glucan wheat flour muffins, and 2.38, 2.18, and 2.23 g for high‐, medium‐, and low‐MW β‐glucan oat flour muffins, respectively. The lower the MW of the β‐glucan in muffins, the lower the height and volume of the muffins. The oat flour muffins were less firm and springy than the wheat flour muffins as measured on a texture analyzer; however, MW had no effect on muffin texture. The oat flour muffins bound more bile acid than did the wheat flour muffins. The muffins with high‐MW β‐glucan bound more bile acid than did those with low‐ and medium‐MW β‐glucan. Muffin treatment affected the formation of gas and total short‐chain fatty acids (SCFA) compared with the blank without substrate during in vitro fermentation. There were no differences in pH changes and total gas production among muffin treatments. The high‐MW β‐glucan wheat flour muffins produced greater amounts of SCFA than did the wheat flour muffin without β‐glucan and the oat flour muffins; however, there were no differences in SCFA production among muffins with different MW. In general, the β‐glucan MW affected the physical qualities of muffins and some potential biological functions in humans.

Human Gut Enterotypes

The advent of high-throughput genomic sequencing has extended our understanding of not only the human genome, but also the genomes of normal commensal human microbial flora. A multinational team of investigators has now undertaken a comprehensive analysis of human fecal flora, based on broad genomic sequencing of samples from individuals in Europe (22), Japan …

Distribution of Human Commensal Escherichia coli Phylogenetic Groups

Most Escherichia coli infections other than gastrointestinal infections are believed to originate from human fecal flora, and the term “extraintestinal pathogenic Escherichia coli ” (ExPEC) was introduced to describe these E. coli strains ([13][1]). However, there is an enormous diversity of

In Vitro Bile-Acid Binding and Fermentation of High, Medium, and Low Molecular Weight β-Glucan

The impact of beta-glucan molecular weight (MW) on in vitro bile-acid binding and in vitro fermentation with human fecal flora was evaluated. beta-Glucan extracted from oat line 'N979-5-4' was treated with lichenase (1,3-1,4-beta-D-glucanase) to yield high (6.87x10(5) g/mol), medium (3.71x10(5) g/mol), and low (1.56x10(5) g/mol) MW fractions. The low MW beta-glucan bound more bile acid than did the high MW beta-glucan (p<0.05). If the positive control, cholestyramine, was considered to bind bile acid at 100%, the relative bile-acid binding of the original oat flour and the extracted beta-glucan with high, medium, and low MW was 15, 27, 24, and 21%, respectively. Significant effects of high, medium, and low MW beta-glucans on total SCFA were observed compared to the blank without substrate (p<0.05). There were no differences in pH changes and total gas production among high, medium, and low MW beta-glucans, and lactulose. The low MW beta-glucan produced greater amounts of SCFA than the high MW after 24 h of fermentation. Among the major SCFA, more propionate was produced from all MW fractions of extracted beta-glucans than from lactulose. In vitro fermentation of extracted beta-glucan fractions with different MW lowered pH and produced SCFA, providing potential biological function.

In Vitro Fermentation of Oat Flours from Typical and High β-Glucan Oat Lines

Two publicly available oat (Avena sativa) lines, "Jim" and "Paul" (5.17 and 5.31% beta-glucan, respectively), and one experimental oat line "N979" (7.70% beta-glucan), were used to study the effect of beta-glucan levels in oat flours during simulated in vitro digestion and fermentation with human fecal flora obtained from different individuals. The oat flours were digested by using human digestion enzymes and fermented by batch fermentation under anaerobic conditions for 24 h. The fermentation progress was monitored by measuring pH, total gas, and short-chain fatty acid (SCFA) production. Significant effects of beta-glucan on the formation of gas and total SCFA were observed compared to the blank without substrate (P < 0.05); however, there were no differences in pH changes, total gas, and total SCFA production among oat lines (P > 0.05). Acetate, propionate, and butyrate were the main SCFA produced from digested oat flours during fermentation. More propionate and less acetate were produced from digested oat flours compared to lactulose. Different human fecal floras obtained from three healthy individuals had similar patterns in the change of pH and the production of gas during fermentation. Total SCFA after 24 h of fermentation were not different, but the formation rates of total SCFA differed between individuals. In vitro fermentation of digested oat flours with beta-glucan could provide favorable environmental conditions for the colon and these findings, thus, will help in developing oat-based food products with desirable health benefits.

Effects of Human Fecal Flora on Intestinal Morphology and Mucosal Immunity in Human Flora‐associated Piglet

Human flora-associated (HFA) piglet model was established to examine the effects of gut microbes from a different donor species on the intestinal morphology and mucosal immunity. Newborn germ-free piglets, obtained by caesarean section, were orally inoculated with a human and a porcine faecal suspension, and artificially fed to establish a HFA group (n = 7) and pig flora-associated (PFA) group (n = 7), respectively. All pigs were killed 6 weeks later. Tissue samples from duodenum, jejunum, ileum and colon were collected and studied by histochemistry and immunohistochemistry methods for intestinal morphological analyses and detection of immunocompetent cells. In summary, both groups of pigs performed well but HFA pigs had a somewhat better daily weight gain, and their jejunal villus height and crypt depth were significantly higher. In comparison with PFA pigs, the number of intraepithelial lymphocytes in jejunum was lower but the number of goblet cells containing neutral mucins was significantly increased in HFA pigs. No difference was observed in the number of mast cells. The areas of IgA producing cells and CD4(+) T cells in the jejunum and IgG producing cells in the small intestine were significantly higher in HFA pigs. However, the areas of MHC class II expressing cells were significantly increased in the duodenum and colon. Additionally, the amount of Bifidobacteria spp. was significantly higher in HFA pigs. This study confirms that the composition of gut microbes differentially affects the host intestinal mucosal immunity and suggests that commensal bacteria have great effects on intestinal health and development.