Luminal and mucosa-associated caecal microbiota of chickens after experimental Campylobacter jejuni infection in the absence of Campylobacter-specific phages of group II and III

Campylobacteriosis is still the most commonly reported zoonosis in the European Union causing gastrointestinal disease in humans. One of the most common sources for these food-borne infections is broiler meat. Interactions between Campylobacter (C.) jejuni and the intestinal microbiota might influence Campylobacter colonization in chickens. The aim of the present study was to gain further knowledge about exclusive interactions of the host microbiota with C. jejuni in Campylobacter-specific phage-free chickens under standardized conditions and special biosafety precautions.Therefore, 12 artificially infected (C. jejuni inoculum with a challenge dose of 7.64 log₁₀ c.f.u.) and 12 control chickens of the breed Ross 308 were kept under special biosafety measures in an animal facility. At day 42 of life, microbiota studies were performed on samples of caecal digesta and mucus. No Campylobacter-specific phages were detected by real-time PCR analysis of caecal digesta of control or artificially infected chickens. Amplification of the 16S rRNA gene was performed within the hypervariable region V4 and subsequently sequenced with Illumina MiSeq platform. R (version 4.0.2) was used to compare the microbiota between C. jejuni-negative and C. jejuni-positive chickens. The factor chickens' infection status contributed significantly to the differences in microbial composition of mucosal samples, explaining 10.6 % of the microbiota variation (P=0.007) and in digesta samples, explaining 9.69 % of the microbiota variation (P=0.015). The strongest difference between C. jejuni-non-infected and C. jejuni-infected birds was observed for the family Peptococcaceae whose presence in C. jejuni-infected birds could not be demonstrated. Further, several genera of the family Ruminococcaceae appeared to be depressed in its abundance due to Campylobacter infection. A negative correlation was found between Christensenellaceae R-7 group and Campylobacter in C. jejuni-colonised chickens, both genera potentially competing for substrate. This makes Christensenellaceae R-7 group highly interesting for further studies that aim to find control options for Campylobacter infections and assess the relevance of this finding for chicken health and Campylobacter colonization.

The microbiota is dispensable for the early stages of peripheral regulatory T cell induction within mesenteric lymph nodes

Intestinal Foxp3+ regulatory T cell (Treg) subsets are crucial players in tolerance to microbiota-derived and food-borne antigens, and compelling evidence suggests that the intestinal microbiota modulates their generation, functional specialization, and maintenance. Selected bacterial species and microbiota-derived metabolites, such as short-chain fatty acids (SCFAs), have been reported to promote Treg homeostasis in the intestinal lamina propria. Furthermore, gut-draining mesenteric lymph nodes (mLNs) are particularly efficient sites for the generation of peripherally induced Tregs (pTregs). Despite this knowledge, the direct role of the microbiota and their metabolites in the early stages of pTreg induction within mLNs is not fully elucidated. Here, using an adoptive transfer-based pTreg induction system, we demonstrate that neither transfer of a dysbiotic microbiota nor dietary SCFA supplementation modulated the pTreg induction capacity of mLNs. Even mice housed under germ-free (GF) conditions displayed equivalent pTreg induction within mLNs. Further molecular characterization of these de novo induced pTregs from mLNs by dissection of their transcriptomes and accessible chromatin regions revealed that the microbiota indeed has a limited impact and does not contribute to the initialization of the Treg-specific epigenetic landscape. Overall, our data suggest that the microbiota is dispensable for the early stages of pTreg induction within mLNs.

Intestinal Microbiota of Fattening Pigs Offered Non-Fermented and Fermented Liquid Feed with and without the Supplementation of Non-Fermented Coarse Cereals

Introducing high numbers of lactic acid bacteria into the gastrointestinal tract of pigs via fermented liquid feed (FLF) could have an impact on intestinal bacterial ecosystems. Twenty piglets were allocated into four groups and fed a botanically identical liquid diet that was offered either non-fermented (twice), fully fermented or partially fermented but supplemented with 40% of non-fermented coarse cereals. Microbiota studies were performed on the small and large intestine digesta and faecal samples. A 16S rRNA gene amplification was performed within the hypervariable region V4 and sequenced with the Illumina MiSeq platform. R (version 3.5.2) was used for the statistical analyses. The digesta of the small intestines of pigs fed FLF were dominated by Lactobacillaceae (relative abundance up to 95%). In the colonic contents, the abundance of Lactobacillaceae was significantly higher only in the pigs fed the FLF supplemented with non-fermented coarse cereals. Additionally, the digesta of the small and large intestines as well as in the faeces of the pigs fed the FLF supplemented with non-fermented coarse cereals were significantly enriched for two operational taxonomic units (OTUs) belonging to the genus Lactobacillus and Bifidobacterium. The FLF supplemented with non-fermented coarse cereals had probiotic and prebiotic-like impacts on the intestinal and faecal bacterial composition of pigs.

THE INFLUENCE OF LIFE-EXTENDING MUTATION AND DIETARY INTERVENTION ON GUT MICROBIOTA

The gastrointestinal microbiota represents a large and complex ecological system of different microorganisms. Recently, there is an increasing interest in the impact of microbiota on development of different age-related diseases. We tested the changes of gut microbiota during development in long-living Ames dwarf (df/df) mice and we compared the effects of this life-extending mutation with the impact of calorie restriction (CR). Importantly, the analysis of microbiome showed significant differences in the ratio of Bacteroidetes and Firmicutes when comparing df/df and normal (N) mice (p<0.001). The LefSe analysis showed distinct microbiome distribution between CR and ad libitum (AL) feeding regimen in N animals (p<0.004), yet there was lack of similar changes in response to CR in df/df mice. In summary, our study showed significant genotype impact on gut microbiota and we showed that life-extending CR regimen provide divergent effects on gut microbiota in N when comparing with df/df mice.

Caecal Microbiota of Experimentally Campylobacter jejuni-Infected Chickens at Different Ages

Campylobacter jejuni is the most common bacterial cause of foodborne zoonosis in the European Union. Infections are often linked to the consumption and handling of poultry meat. The aim of the present study was to investigate the caecal microbiota of birds infected with C. jejuni at different ages. Therefore, a total of 180 birds of the laying hybrid Lohmann Brown-Classic were housed in 12 subgroups of 15 animals each in three performed repetitions. Three birds per subgroup were experimentally infected with C. jejuni at an age of about 21 days and about 78 days (4.46 ± 0.35 log10 CFU/bird). Twenty-one days after experimental infection, microbiome studies were performed on 72 caecal samples of dissected birds (three primary infected and three further birds/subgroup). Amplification within the hypervariable region V 4 of the 16S rRNA gene was performed and sequenced with the Illumina MiSeq platform. Statistical analyses were performed using SAS® Enterprise Guide® (version 7.1) and R (version 3.5.2). Both factors, the experimental replication (p < 0.001) and the chickens' age at infection (p < 0.001) contributed significantly to the differences in microbial composition of the caecal samples. The factor experimental replication explained 24% of the sample's variability, whereas the factor age at infection explained 14% thereof. Twelve of 32 families showed a significantly different count profile between the two age groups, whereby strongest differences were seen for seven families, among them the family Campylobacteraceae (adjusted p = 0.003). The strongest difference between age groups was seen for a bacterial species that is assigned to the genus Turicibacter which in turn belongs to the family Erysipelotrichaceae (adjusted p < 0.0001). Correlation analyses revealed a common relationship in both chicken ages at infection between the absolute abundance of Campylobacteraceae and Alcaligenaceae, which consists of the genus Parasutterella. In general, concentrations of particular volatile fatty acids (VFA) demonstrated a negative correlation to absolute abundance of Campylobacteraceae, whereby the strongest link was seen for n-butyrate (-0.51141; p < 0.0001). Despite performing consecutive repetitions, the factor experimental replication contributed more to the differences of microbial composition in comparison to the factor age at infection.

Performance, Fermentation Characteristics and Composition of the Microbiome in the Digest of Piglets Kept on a Feed With Humic Acid-Rich Peat

The transition from breast milk to solid feed is a dramatic change in the nutrition of piglets, frequently necessitating antibiotic treatment. In efforts to reduce the use of antibiotics, dietetic concepts based on natural feed additives are becoming more and more important. In the present study, experiments were carried out with 15 rearing piglets (days 28–56) divided into three groups that were offered different diets (Ctr [0% peat]; H1.5 [1.5% peat]; and H3.0 [3.0% peat] based on a commercial weaner recipe; all ~178 g CP, 13.7 MJ ME, 13.3 g Lys, as-fed). The contents of cecal and colon digesta were removed at necropsy. The gas formation (4 h) in colon digesta was measured using in vitro batch fermenters. For microbiome studies, 16S rRNA amplification was performed within the hypervariable region V 4 and sequenced with Illumina MiSeq platform. DNA read mapping and statistical analysis were performed using QIIME (version 1.8.0), MicrobiomeAnalyst, RStudio, and SAS Enterprise Guide. The mean body weight of the animals at the end of the trial did not show statistical differences (in kg: Ctr: 26.1 ± 4.85, H1.5: 28.5 ± 3.41, H3.0: 26.2 ± 4.92). The daily weight gains were high for this age (in g/day; Ctr: 607 ± 157; H1.5: 692 ± 101; H3.0: 615 ± 113) and the feed to gain ratio low (in kg/kg; Ctr: 1.538; H1.5: 1.462; H3.0: 1.462). Concentrations of short-chain fatty acids in the cecal content were significantly lower when peat was used (mmol/kg wet weight; Ctr: 173 ± 30.0; H1.5:134 ± 15.0; H3.0:133 ± 17.3). Numerical differences were found in the gas formation (in mL gas per 10 mL batch in 4 h; Ctr: 7.9 ± 2.2; H1.5: 7.4 ± 2.4; H3.0: 6.6 ± 1.1). The microbiome analyses in the cecal content showed significantly higher values for alpha diversity Chao 1 index for samples from the control group. Significant differences were found for bacterial relative abundance for Tenericutes at phylum level and Mollicutes at class level (p < 0.05) in cecal microbiota. Therefore, there was initial evidence that peat influences intestinal microflora causing a shift in the overall concentration of fermentation products in both, the cecal and the colon content.

Synthesis and structural, conformational, biochemical, and pharmacological study of new compounds derived from tropane-3-spiro-4'(5')-imidazoline as potential 5-HT3 receptor antagonists

A series of tropane-3-spiro-4'(5')-imidazolines was synthesized and studied by 1H and 13C NMR spectroscopy, and the crystal structure of 2'-(1H-indol-3-yl)tropane-3-spiro-4'(5')-imidazoline hydrochloride 5(6)f was determined by X-ray diffraction. In CD3OD solution, compounds 5(6)a-f display the same preferred conformation. The pyrrolidine and piperidine rings adopt an envelope conformation flattened at N8 and a distorted chair conformation puckered at N8 and flattened at C3, respectively, with the N-substituent in the equatorial position with respect to the piperidine ring. This conformation is similar to that observed for compound 5(6)f in the solid state. From binding studies on the compounds synthesized, compound 5(6)d demonstrated the ability to efficiently displace the binding of [3H]GR65630 to bovine brain area postrema membranes to an extent comparable to MDL 72222. In the von Bezold-Jarisch reflex, compound 5(6)d was equipotent with metoclopramide. It is, therefore, likely that the imidazoline ring may provide a useful bioisosteric replacement for the carbonyl group in 5-HT3 antagonists.

Structural study of benzidamine salicylate in the solid state and in solution

The vibrational (IR and Raman) and 1H and 13C NMR spectra of the analgesic and anti-inflammatory benzidamine salicylate (Benzasal) have been examined, and the results are described. The crystal structure of this compound has been determined by X-ray diffraction. To assist in interpretation of the spectroscopic data, some measurements of benzidamine, benzidamine hydrochloride, and salicylic acid have also been made. The most important intermolecular interactions of benzidamine salicylate in the solid state are N(+)H...O(-)...-C hydrogen bonds involving both salicylate oxygen atoms (d = 2.658 A and 3.228 A). At least the stronger hydrogen bond remains in CDCl3 solution. Moreover, the strong intramolecular hydrogen bond O-H...O(-)...-C within the salicylate anion has also been observed in the solid state and in solution.

Synthesis and structural, conformational, and pharmacological study of some of esters derived from 3-phenethyl-3-azabicyclo[3.2.1]octan-8-beta-ol and the corresponding N-endo-methyl quaternary derivatives

A series of 8-beta-acyloxy-3-phenethyl-3-azabicyclo[3.2.1]octane and its N-endo methiodides were synthesized and studied by 1H and 13C NMR spectroscopy, and the crystal structure of 8-beta-p-chlorobenzoyloxy-3-phenethyl-3-azabicyclo[3.2.1]octane methiodide (2c) was determined by X-ray diffraction. In CDCl3 solution, 1b-1e display the same preferred conformation. The cyclopentane and piperidine rings adopt an envelope conformation flattened at C-8 and a distorted chair conformation puckered at C-8 and flattened at N-3, respectively, with the N-substituent in the equatorial position with respect to the piperidine ring. In all cases, methylation takes place from the endo position. The ability of the title compounds to antagonize the acetylcholine-induced contraction of guinea pig ileum is also reported. An initial structure-activity relationship is proposed.

Synthesis and structural study of N-substituted nortropane spirohydantoins

A series of N8-alkyloxycarbonylalkyl-nortropane-3-spiro-5'-hydantoins has been synthesized and studied by spectral and crystallographic methods. The crystal and molecular structure of one [8(gamma-ethoxycarbonyl)nortropane-3-spiro-5'-hydantoin, VI] was determined by X-ray diffraction. The preferred conformations of these compounds and subsequent changes on protonation were determined from 1H-NMR and 13C-NMR data.