Search Results (41)

Oxidative stress (OS) is a major concern in young poultry and livestock, prompting extensive research on OS models. This study aimed to systematically investigate the dynamic effects and temporal trends of OS induced with lipopolysaccharide (LPS) over time. Twenty-eight piglets were randomly divided into four groups and equally intraperitoneally injected with LPS at doses of 0 μg/kg (control), 50 μg/kg (L-LPS), 100 μg/kg (M-LPS) and 150 μg/kg (H-LPS) body weight, respectively. The results showed that total antioxidant capacity (T-AOC), total superoxide dismutase (T-SOD), and catalase (CAT) were decreased, while malondialdehyde (MDA), nitric oxide (NO), inducible nitric oxide synthase (iNOS), interleukin-6 (IL-6), IL-1β, tumor necrosis factor-α (TNF-α), diamine oxidase (DAO) and D-lactic acid (D-LA) were increased in the M-LPS and H-LPS group on day 1 in comparison with the control group, but no differences were found among treatments on day 7. However, LPS treatments gave rise to varying degrees of pathological injury in the intestines, livers and spleens on day 7. Metabolomics analysis indicated that compared with the control group, glycyl-valine, histamine and lepidine F were decreased in the M-LPS group. Most differentially expressed metabolites were enriched in amino acid-related metabolism pathways on both day 1 and day 7. Microbiome analysis identified that Oscillibacter_sp._CAG:241 was decreased in the M-LPS group compared with the control group on day 1, while Bacteroides_thetaiotaomicron and Lactobacillus_amylovorus were reduced in the M-LPS group on day 7. Collectively, an LPS dose of 100 μg/kg body weight is optimal for inducing acute inflammation in Wuzhishan miniature pigs. These findings highlight the importance of considering both the duration of OS induction and the specific research objectives when establishing OS models. Full article

Bacterial extracellular vesicles (BEVs) produced by members of the intestinal microbiota can not only contribute to digestion but also mediate microbe–host cell communication via the transfer of functional biomolecules to mammalian host cells. An unresolved question is which host factors and conditions influence BEV cargo and how they impact host cell function. To address this question, we analysed and compared the proteomes of BEVs released by the major human gastrointestinal tract (GIT) symbiont Bacteroides thetaiotaomicron (Bt) in vivo in fed versus fasted animals using nano-liquid chromatography with tandem mass spectrometry (LC-MSMS). Among the proteins whose abundance was negatively affected by fasting, nine of ten proteins of the serine protease family, including the regulatory protein dipeptidyl peptidase-4 (DPP-4), were significantly decreased in BEVs produced in the GITs of fasted animals. Strikingly, in extracellular vesicles produced by the intestinal epithelia of the same fasted mice, the proteins with the most increased abundance were serine protease inhibitors (serpins). Together, these findings suggest a dynamic interaction between GI bacteria and the host. Additionally, they indicate a regulatory role for the host in determining the balance between bacterial serine proteases and host serpins exported in bacterial and host extracellular vesicles. Full article

The role of gut microbiota (GM) and intestinal dysbiosis in triggering the onset and/or modulating the severity and progression of lupus nephritis (LN) has been the object of intense research over the last few years. Some alterations at the phyla level, such as the abundance of Proteobacteria and reduction in Firmicutes/Bacteroidetes (F/B) ratio and in α-diversity have been consistently reported in systemic lupus erythematosus (SLE), whereas a more specific role has been ascribed to some species (Bacteroides thetaiotaomicron and Ruminococcus gnavus) in LN. Underlying mechanisms include microbial translocation through a “leaky gut” and subsequent molecular mimicry, immune dysregulation (alteration of IFNγ levels and of balance between Treg and Th17 subsets), and epigenetic interactions. Levels of bacterial metabolites, such as butyrate and other short-chain fatty acids (SCFAs), appear to play a key role in modulating LN. Beyond bacterial components of GM, virome and mycobiome are also increasingly recognized as important players in the modulation of an immune response. On the other hand, microbiota-based therapy appears promising and includes diet, prebiotics, probiotics, symbiotics, and fecal microbiota transplantation (FMT). The modulation of microbiota could correct critical alterations, such as F/B ratio and Treg/Th17 imbalance, and blunt production of autoantibodies and renal damage. Despite current limits, GM is emerging as a powerful environmental factor that could be harnessed to interfere with key mechanisms leading to SLE, preventing flares and organ damage, including LN. The aim of this review is to provide a state-of-the-art analysis of the role of GM in triggering and modulating SLE and LN on the one hand, while exploring possible therapeutic manipulation of GM to control the disease on the other hand. Full article

The present study evaluates the effects of açai juice containing gluco-oligosaccharides and dextran, fermented by Bifidobacterium breve NRRL B-41408 (synbiotic juice), on the human fecal microbiota. The juice is subjected to simulated digestion and fecal fermentation after production and 42 days of refrigerated storage. High throughput 16S rRNA sequencing and HPLC are used to identify the bacterial cells and metabolites. The results show that the viability of B. breve is stable during the refrigerated storage, indicating that the metabolism is maintained even under low temperatures and pH. Furthermore, gluco-oligosaccharides and dextran prove to be resistant to gastrointestinal conditions and are quickly consumed during fecal fermentation. The synbiotic açai juice enhances the microbial diversity and stimulates the production of short-chain fatty acids (SCFA), including acetate, propionate, and isobutyrate. Elevated propionate levels are directly associated with an increased abundance of Bacteroides thetaiotaomicron, Bacteroides uniformis, Bacteroides xylanisolvens, Bacteroides dorei, Bacteroides stercoris, and Bacteroides massiliensis after 48 h of fermentation. This highlights the potential of synbiotic açai juice as a functional beverage, supported by the significant increase in microbial diversity reflected in the Shannon and Simpson’s diversity indexes (Shannon = 116.6%, 117.2%, 125.15%, and 116.02%; Simpson’s = 151.86%, 177.22%, 152.5%, and 163.73%). Full article

Targeted saturation mutagenesis at the residues located at the substrate-binding pocket for generating focused libraries has emerged as the technique of choice for enzyme engineering, but choosing the optimal residue number of the randomization site and the reduced amino acid alphabet to minimize the labor-determining screening effort remains a challenge. Herein, we propose the six-codon combinatorial mutagenesis (SCCM) strategy by using the BMT degeneracy codons encoding six amino acids with different chemical properties as the building blocks for the randomization of the amnio acid motif. SCCM requires only a small library of 646 clones for 95% coverage at the three-residue motif compared to conventional NNK degeneracy codons encoding all 20 canonical amino acids and requiring the screening of nearly 100,000 clones. SCCM generates a suitable number of mutant libraries, providing a new strategy for reducing the screening workload of saturated combination mutations in enzyme engineering. Using this approach, the α-L-rhamnosidase BtRha78A from Bacteroides thetaiotaomicron had been successfully engineered for improving the hydrolytic activity on natural flavonoid diglycoside hesperidin via targeted directed evolution at the motifs positioning the entrance of the substrate-binding pocket. The results indicate that the conversion rates of the four mutants on hesperidin were increased by more than 30% compared with the wild type using whole-cell biotransformation. Moreover, the catalytic efficiency k_cat/K_M value of the mutant TM1-6-F5 was 1.4-fold higher than that of the wild type. Full article

A substantial body of research indicates that the gut microbiota exerts a profound influence on host health. The purpose of this work was to characterize selected, most promising, well-known next-generation probiotics (NGPs) and review the potential applications of the bacteria in food technology. The isolation of gut bacteria with significant health benefits has led to the emergence of NGPs. In contrast to traditional probiotics, these originate directly from the gut microbiota, thereby ensuring their optimal adaptation to the intestinal ecosystem. NGPs exert their effects on the host organism through a variety of mechanisms, including the synthesis of bioactive compounds, modulation of the gut microbiota, and metabolism of substances provided by the host. Several bacterial species have been identified as potential candidates for NGPs, including Akkermansia muciniphila, Faecalibacterium prausnitzii, Bacteroides thetaiotaomicron, Christensenella minuta, and many others. These bacteria have demonstrated the capacity to exert beneficial effects, including the reduction of obesity, type 2 diabetes, metabolic disorders, and even cancers. The greatest limitation to their commercialization is their lack of oxygen tolerance, which presents challenges not only for research but also for their potential application in food. The most optimal approach for their application in food appears to be microencapsulation. Further research is required to establish the safety of NGP supplementation and to protect them from environmental conditions. Full article

Sanfilippo syndrome, or mucopolysaccharidosis type III (MPS III), is a rare lysosomal disease caused by congenital enzymatic deficiencies in heparan sulfate (HS) degradation, leading to organ dysfunction. The most severe hallmark of MPS III comprises neurological alterations, although gastrointestinal symptoms (GISs) have also been shown to be relevant in many patients. Here, we explored the contribution of the gut microbiota to MPS III GISs. We analyzed the composition and functionality of the gut microbiota in two MPS III siblings with the same mutation (c.544C > T, c.1080delC, in the SGSH gene) and the same diet, but with differences in their GISs, including recurrent diarrhea in one of them. Using 16S sequencing, we observed that the MPS III patients exhibited decreased alpha diversity and a lower abundance of Lachnospiraceae and Bifidobacteriaceae accompanied by a higher abundance of the Ruminococcaceae and Rikenellaceae families than the healthy control subjects. Comparing siblings, we found an increased abundance of Bacteroidaceae and a lower abundance of Ruminococcaceae and Akkermansiaceae in the GIS-free patient. This patient also had a higher relative abundance of Sus genes (SusA, SusB, SusE, and SusG) involved in glycosaminoglycan metabolism. We found higher HS levels in the stool of the two MPS III patients than in healthy volunteers, particularly in the patient with GISs. Functionally, whole fecal metabolites from the patient with GISs induced oxidative stress in vitro in healthy monocytes. Finally, the Bacteroides thetaiotaomicron strain isolated from MPS III stool samples exhibited HS degradation ability. Overall, our results reveal different microbiota compositions and functionalities in MPS III siblings, who exhibited differential gastrointestinal symptomatology. Our study may serve as a gateway to explore the impact of the gut microbiota and its potential to enhance the quality of life in Sanfilippo syndrome patients. Full article

α-L-Rhamnosidases with desirable activity and thermostability profiles could be used for the biocatalytic production of the flavonoid glucoside isoquercetin from natural rutin for functional food. Herein, to improve the catalytic activity of GH78 α-L-rhamnosidase BtRha78A from Bacteroides thetaiotaomicron VPI-5482, a list of residues located at the conserved general acid motif were selected for targeted mutagenesis by the sequence alignment of BtRha78A with homologous α-L-rhamnosidases. Ala-scanning mutagenesis and site-directed mutagenesis based on sequence alignment were performed, and the relative activity on rutin was evaluated. Furthermore, the reaction time curves and enzyme kinetics of better mutants were determined. The results indicate that the conversion rates of mutants V338A, V338I, S340A, and G341A were increased by 21.3%, 20.1%, 13.2%, and 1.6%, respectively, compared with the wild type when using whole-cell biotransformation. Moreover, the catalytic efficiency k_cat/K_M value of mutant V338A was 1.3-fold higher than that of the wild type. The best mutant, V338A, was employed for the enzymatic preparation of isoquercetin via the biotransformation of rutin at a concentration of 2 mM, and 1.80 g of isoquercetin was obtained. The identification of the best mutant V338A lays the foundation for the efficient preparation of isoquercetin via the biotransformation of rutin, which in turn provides theoretical guidance for its large-scale production. Full article

In the present study, four Bacteroides species that could degrade Fuzhuan brick tea polysaccharide-3 (FBTPS-3) were isolated from human feces and identified to be Bacteroides ovatus, B. uniformis, B. fragilis and B. thetaiotaomicron. The four Bacteroides species showed growth on FBTPS-3 as the carbon source, and B. ovatus showed the best capability for utilizing FBTPS-3 among the four species since B. ovatus could utilize more FBTPS-3 during 24 h fermentation. Moreover, the four Bacteroides species could metabolize FBTPS-3 and promote the production of acetic, propionic and isovaleric acids. Transcriptome analysis of B. ovatus revealed that 602 genes were up-regulated by FBTPS-3, including two carbohydrate-active enzyme clusters and four polysaccharide utilization loci (PULs). The PUL 1 contained GH28 family that could hydrolyze rhamnogalacturonan and other pectic substrates, which was in line with our previous work that rhamnose and galacturonic acid were the main component monosaccharides of FBTPS-3. Collectively, the results suggested that FBTPS-3 could be utilized by Bacteroides spp., and it might be developed as a promising prebiotic targeting Bacteroidetes in intestinal environment. Full article

Indole-3-acetic acid (IAA), a protein-bound uremic toxin resulting from gut microbiota-driven tryptophan metabolism, increases in hemodialysis (HD) patients. IAA may induce endothelial dysfunction, inflammation, and oxidative stress, elevating cardiovascular and cognitive risk in HD patients. However, research on the microbiome–IAA association is limited. This study aimed to explore the gut microbiome’s relationship with plasma IAA levels in 72 chronic HD patients aged over 18 (August 2016–January 2017). IAA levels were measured using tandem mass spectrometry, and gut microbiome analysis utilized 16s rRNA next-generation sequencing. Linear discriminative analysis effect size and random forest analysis distinguished microbial species linked to IAA levels. Patients with higher IAA levels had reduced microbial diversity. Six microbial species significantly associated with IAA levels were identified; Bacteroides clarus, Bacteroides coprocola, Bacteroides massiliensi, and Alisteps shahii were enriched in low-IAA individuals, while Bacteroides thetaiotaomicron and Fusobacterium varium were enriched in high-IAA individuals. This study sheds light on specific gut microbiota species influencing IAA levels, enhancing our understanding of the intricate interactions between the gut microbiota and IAA metabolism. Full article

The farnesoid X receptor (FXR)/βKlotho/fibroblast growth factors (FGFs) pathway is crucial for maintaining the intestinal barrier and preventing colorectal cancer (CRC). We used an FXR agonist, GW4064, and FXR-knockout (FXR-KO) mice to investigate the role of FXR/Klothos/FGFs pathways in lipopolysaccharide (LPS)-induced intestinal barrier dysfunction and colon carcinogenesis. The results showed that upregulation of FXR in enterocytes effectively ameliorated intestinal tight-junction markers (claudin1 and zonula occludens-1), inflammation, and bile acid levels, thereby protecting mice from intestinal barrier dysfunction and colon carcinogenesis. GW4064 treatment increased FXR, αKlotho, βKlotho, FGF19, FGF21, and FGF23 in wild-type mice exposed to LPS, while FXR-KO mice had decreased levels. FXR-KO mice exhibited elevated colon cancer markers (β-catenin, LGR5, CD44, CD34, and cyclin D1) under LPS, underscoring the pivotal role of FXR in inhibiting the development of colon tumorigenesis. The varying gut microbiota responses in FXR-KO mice versus wild-type mice post LPS exposure emphasize the pivotal role of FXR in preserving intestinal microbial health, involving Bacteroides thetaiotaomicron, Bacteroides acidifaciens, and Helicobacter hepaticus. Our study validates the effectiveness of GW4064 in alleviating LPS-induced disruptions to the intestinal barrier and colon carcinogenesis, emphasizing the importance of the FXR/αKlotho/βKlotho/FGFs pathway and the interplay between bile acids and gut microbiota. Full article

The impact of prebiotics on human health is associated with their capacity to modulate microbiota, improving beneficial microbiota–host interactions. Herein, the prebiotic potential of microbial-fructo-oligosaccharides (microbial-FOSs) produced by a co-culture of Aspergillus ibericus plus Saccharomyces cerevisiae was evaluated on seven- and nine-strain bacterial consortia (7SC and 9SC, respectively), designed to represent the human gut microbiota. The 7SC was composed of Bacteroides dorei, Bacteroides vulgatus, Bifidobacterium adolescentis, Bifidobacterium longum, Escherichia coli, Lactobacillus acidophilus, and Lactobacillus rhamnosus. The 9SC also comprised the aforementioned bacteria, with the addition of Bacteroides thetaiotaomicron and Roseburia faecis. The effect of microbial-FOSs on the metabolic activity of intestinal Caco-2/HT29-MTX-E12 co-culture was also assessed. The results showed that microbial-FOS selectively promoted the growth of probiotic bacteria and completely suppressed the growth of E. coli. The microbial-FOSs promoted the highest production rates of lactate and total short-chain fatty acids (SCFA) as compared to the commercial prebiotic Frutalose^® OFP. Butyrate was only produced in the 9SC consortium, which included the R. faecis—a butyrate-producing bacteria. The inclusion of this bacteria plus another Bacteroides in the 9SC promoted a greater metabolic activity in the Caco-2/HT29-MTX-E12 co-culture. The microbial-FOSs showed potential as promising prebiotics as they selectively promote the growth of probiotic bacteria, producing high concentrations of SCFA, and stimulating the metabolic activity of gut cells. Full article

Dietary intake of the sulfated polysaccharide from edible alga E. clathrata (ECP) has recently been illustrated to attenuate ulcerative colitis (UC) by targeting gut dysbiosis in mice. However, ECP is not easily absorbed in the gut and, as a potential candidate for next-generation prebiotics development, how it is fermented by human gut microbiota has not been characterized. Here, using in vitro anaerobic fermentation and 16S high-throughput sequencing, we illustrate for the first time the detailed fermentation characteristics of ECP by the gut microbiota of nine UC patients. Our results indicated that, compared to that of glucose, fermentation of ECP by human gut microbiota produced a higher amount of anti-inflammatory acetate and a lower amount of pro-inflammatory lactate. Additionally, ECP fermentation helped to shape a more balanced microbiota composition with increased species richness and diversity. Moreover, ECP significantly stimulated the growth of anti-colitis bacteria in the human gut, including Bacteroides thetaiotaomicron, Bacteroides ovatus, Blautia spp., Bacteroides uniformis, and Parabacteroides spp. Altogether, our study provides the first evidence for the prebiotic effect of ECP on human gut microbiota and sheds new light on the development of ECP as a novel prebiotic candidate for the prevention and potential treatment of UC. Full article

The high throughput in genome sequencing and metabolic model (MM) reconstruction has democratised bioinformatics approaches such as flux balance analysis. Fluxes’ prediction accuracy greatly relates to the deepness of the MM curation for a specific organism starting from the cell composition. One component is the cell wall, which is a functional barrier (cell shape, exchanges) with the environment. The bacterial cell wall (BCW), including its thickness, structure, and composition, has been extensively studied in Escherichia coli but poorly described for other organisms. The peptidoglycan (PG) layer composing the BCW is usually thinner in Gram− bacteria than in Gram+ bacteria. In both bacteria groups, PG is a polymeric mesh-like structure of amino acids and sugars, including N-acetylglucosamine, N-acetylmuramic acid, and amino acids. In this study, we propose a high-throughput method to characterise and quantify PG in Gram-positive and Gram-negative bacteria using acidic hydrolysis and hydrophilic interaction liquid chromatography coupled with mass spectrometry (HILIC-MS). The method showed a relatively short time frame (11 min analytical run), low inter- and intraday variability (3.2% and 4%, respectively), and high sensitivity and selectivity (limits of quantification in the sub mg/L range). The method was successfully applied on two Gram-negative bacteria (Escherichia coli K12 MG1655, Bacteroides thetaiotaomicron DSM 2079) and one Gram-positive bacterium (Streptococcus salivarius ssp. thermophilus DSM20259). The PG concentration ranged from 1.6% w/w to 14% w/w of the dry cell weight. The results were in good correlation with previously published results. With further development, the PG concentration provided by this newly developed method could reinforce the curation of MM. Full article

Gallstone disease (GD) is one of the most common gastrointestinal diseases worldwide. Nowadays, intestinal microbiota are thought to play important roles in the formation of gallstones. In our study, human fecal samples were extracted for metagenomic next-generation sequencing (mNGS) on the Illumina HiSeq platform, followed by bioinformatics analyses. Our results showed that there was a particular intestinal micro-ecosystem in GD patients. In contrast to healthy people, the sequences of Bacteroidetes, Bacteroides and Thetaiotaomicron were obviously more abundant in GD patients at phylum, genus and species levels, respectively. On the other hand, the glycan metabolism and drug resistance, especially for the β-lactams, were the most profound functions of gut microbes in GD patients compared to those in normal subjects. Furthermore, a correlation analysis drew out that there existed a significant relationship between the serum levels of biochemical indicators and abundances of intestinal microbes in GD patients. Our results illuminate both the composition and functions of intestinal microbiota in GD patients. All in all, our study can broaden the insight into the potential mechanism of how gut microbes affect the progression of gallstones to some extent, which may provide potential targets for the prevention, diagnosis or treatment of GD. Full article