Amino acid utilization allows intestinal dominance of Lactobacillus amylovorus

Lactic acid bacteria fermentation: A novel and promising pathway to lower the uric acid production of seaweed food (Porphyra haitanensis)

Porphyra haitanensis is a highly nutritious and widely consumed seaweed food. However, it is a high-purine food, which can increase the risk of disease for individuals with hyperuricemia. To address this issue, three lactic acid bacteria strains, including Lactiplantibacillus plantarum, Lacticaseibacillus paracasei, and Lacticaseibacillus rhamnosus, are utilized to investigate the effects of fermentation on Porphyra haitanensis to reduce the purine content and the activity of xanthine oxidase (XOD) and adenosine deaminase (ADA). All the three lactic acid bacteria strains can significantly reduce in xanthine content and effectively inhibit ADA and XOD activities. The xanthine content can be reduced by 47.80 % after Lactiplantibacillus plantarum fermentation. The inhibition ratio of XOD in Lacticaseibacillus rhamnosus fermentation is as high as to 91.39 %, which is improved by 308.30 %. The inhibition ratio of ADA can be improved by 515.35 % after Lactiplantibacillus plantarum fermentation. Metabolomic analysis is applied to elucidate the key metabolites associated with activity inhibition and molecular docking is performed to reveal the inhibition mechanisms. Folic acid and cis-zeatin were identified as key differential metabolites for the inhibition of XOD and ADA activities, exhibiting strong binding affinities toward both of the two enzymes. This is among the first known reports that the lactic acid bacteria fermentation is utilized to lower the uric acid production of seaweed Porphyra haitanensi. These findings highlight the potential of lactic acid bacteria fermentation as an effective strategy for reducing purine levels in seaweed-derived functional foods, providing novel dietary interventions for hyperuricemia management.

OVA-Induced Food Allergy Leads to Neurobehavioral Changes in Mice and the Potential Role of Gut Microbiota and Metabolites Dysbiosis

The neurobehavioral changes in food allergy mice have not been comprehensively studied, and the mechanism underlying them remains unclear. Our study aims to fully investigate neurobehavioral changes in OVA (ovalbumin)-sensitized food allergy mice and explore the potential mechanism via the gut microbiota-brain axis. We established the food allergy mouse (C57BL/6J male) model with OVA, evaluating the anaphylactic symptoms and the levels of Th2 signature cytokine and allergy-related antibodies in serum. Using behavioral tests, we measured anxiety, depression, social behavior, repetitive behavior, attention, and spatial memory in control and OVA mice. In addition, we analyzed the prefrontal cortex for measuring inflammation-related indicators and gathered serum for untargeted metabolomics analysis and feces for 16S rDNA sequencing. OVA mice exhibited anaphylactic symptoms and significantly elevated serum IgE and Th2 signature cytokine levels. In addition to anxiety-like, depression-like, and repetitive behaviors, OVA mice also displayed less social interest and damaged attention. TNF-α, IL-1β, and IL-6 levels and the activation of microglia in the prefrontal cortex of OVA mice were significantly increased, which might explain the neuronal damage. Using multi-omics technology, amino acid metabolism disruption, particularly carboxylic acids and derivatives, was observed in OVA mice, which was remarkably correlated with the altered abundance of gut microbiota related to food allergy. Behaviors in OVA-induced food allergy mice were extensively impaired. The disruption of amino acid metabolism associated with gut microbiota dysbiosis in OVA mice might play a pivotal role in impairing neural immune homeostasis and neuronal damage, which could be responsible for behavioral abnormalities.

Nanocoating of quinoa protein and hyaluronic acid enhances viability and stability of Limosilactobacillus fermentum RC4 microcapsules

Nanocoating represents an effective strategy for creating a protective barrier on probiotic surfaces, preventing them from damage. Here, we developed HAQ microcapsules comprising Limosilactobacillus fermentum RC4, which were nanocoated with hyaluronic acid and quinoa protein. We characterized the stability and safety, and investigated the intermolecular forces and transcriptome to elucidate the mechanisms underlying the nanocoating. The encapsulation efficiency, survival rates following freeze drying, simulated oro-gastrointestinal conditions, and storage at 4 °C for 56 d were 10.32 %, 12.74 %, 7.56 %, and 14.56 % higher, respectively, than those of LF RC4 alone. The HAQ microcapsules demonstrated adhesion to Caco-2 cells and safely promoted proliferation in RAW 264.7 cells. Electrostatic and hydrophobic interactions emerged as the primary forces within the HAQ microcapsules, facilitating structural rearrangements of wall materials, promoting the ordered aggregation of quinoa protein, and enhancing the stability of microcapsules. Transcriptome analysis revealed that HAQ upregulated argF and carB involved in lysine and glutamic acid biosynthesis, while downregulating mraY and murG associated with carbohydrate biosynthesis. It is postulated that these regulatory effects may enhance bacterial metabolism and proliferation, thereby facilitating the exertion of functional properties such as adhesion. Our findings offer valuable insights into the development of highly active and stable probiotic freeze-dried powders.

Casein Hydrolysate Enhances Upper Gastrointestinal Chemosensing and Gastric Acid Secretion in Pigs

Gastric chemosensing and gastric acid secretion affect nutrient utilization. Dietary peptides influence intestinal amino acid utilization, yet their regulation of gastric chemosensing and gastric acid secretion remains unknown. Herein, a pig model was employed to study the gastric response to dietary peptide-enriched casein hydrolysate versus intact casein. A total of 16 crossbred pigs (Duroc × Landrace × Yorkshire; 19.09 ± 0.61 kg; 63 ± 2 days of age) were randomly assigned to either an intact casein supplementation diet (n = 8) or a hydrolyzed casein supplementation diet (n = 8) for 28 days. Results showed that casein hydrolysate increased hydrochloric acid concentrations, parietal cell numbers, and H+-K+-ATPase activities in the stomach. Gastric chemosensing was upregulated, as indicated by the increased expression of peptide and amino acid chemosensors (G Protein-Coupled Receptor 92 and Calcium-Sensing Receptor) in the dorsum of the tongue, gastric corpus, and antrum. Signaling pathways involved in gastric acid secretion were also enhanced by casein hydrolysate, including extracellular stimuli (histamine, gastrin, and acetylcholine), their receptors, and intracellular signaling molecules. The upregulated gastric acid secretion was accompanied by lower amino acid concentrations in the gastric digesta and increased pepsin activity. These results demonstrate that casein hydrolysate enhances gastric chemosensing and gastric acid secretion, providing a promising nutritional strategy for regulating amino acid digestion.

The discrepancy in amino acids within high-temperature Daqu: A novel metabolic marker for the quality evaluation of Daqu

Mechanical pressing in Daqu production has introduced quality-affecting variations. Up to now, clear elucidation has not yet been applied to the mechanisms behind this phenomenon, and the determinants of Daqu quality are not yet completely excavated. For this reason, the physicochemical factors, enzyme activity, metabolites, and microbial communities were compared between the mechanical Daqu (MDQ) and traditional Daqu (TDQ) in this paper. The results showed significant differences in amino acids between MDQ and TDQ, with arginine being the key differentiator. High temperature, high moisture, and low acidity were crucial to Daqu's amino acid richness. Additionally, mechanical pressing affected core community stability. Bacillus was the primary biological factor for the discrepancy in amino acids. Further investigation indicated that arginine contributed to the reduction of lactic acid and higher alcohols in Jiupei, confirming that amino acids were potential novel markers affecting the quality of Daqu.

Metatranscriptomics for Understanding the Microbiome in Food and Nutrition Science

Microbiome science has greatly expanded our understanding of the diverse composition and function of gut microorganisms over the past decades. With its rich microbial composition, the microbiome hosts numerous functionalities essential for metabolizing food ingredients and nutrients, resulting in the production of active metabolites that affect food fermentation or gut health. Most of these processes are mediated by microbial enzymes such as carbohydrate-active enzymes and amino acid metabolism enzymes. Metatranscriptomics enables the capture of active transcripts within the microbiome, providing invaluable functional insights into metabolic activities. Given the inter-kingdom complexity of the microbiome, metatranscriptomics could further elucidate the activities of fungi, archaea, and bacteriophages in the microbial ecosystem. Despite its potential, the application of metatranscriptomics in food and nutrition sciences remains limited but is growing. This review highlights the latest advances in food science (e.g., flavour formation and food enzymology) and nutrition science (e.g., dietary fibres, proteins, minerals, and probiotics), emphasizing the integration of metatranscriptomics with other technologies to address key research questions. Ultimately, metatranscriptomics represents a powerful tool for uncovering the microbiome activity, particularly in relation to active metabolic processes.

Deaminase inhibitor and casein hydrolysates drive microbial shifts favoring Campylobacter jejuni in an in vitro poultry cecal model

AIM

The dietary proteins in poultry feeds, including the polypeptide chain size, influence gut microbial composition and function. This study assessed the microbial preference for peptide size using the same protein source in three polypeptide forms.

METHODS AND RESULTS

We investigated the effects of diphenyliodonium chloride (DIC) on poultry cecal microbiota inoculated with Campylobacter jejuni and supplemented with various casein hydrolysates (intact casein, enzyme hydrolysate, acid hydrolysate, and a mix of all three) using an in vitro cecal model. The incubation occurred over 18 h at 42°C under microaerophilic conditions. We hypothesized a decrease in C. jejuni abundance by limiting nitrogenous metabolites while promoting the growth of protein fermentative bacteria. Additionally, we speculated that the response to DIC would vary with different polypeptides. Genomic DNA was extracted, amplified, and sequenced on an Illumina MiSeq platform. Analysis within QIIME2-2021.11 showed that DIC treatments did not significantly affect C. jejuni abundance but drastically decreased Enterobacteriaceae abundance (ANCOM, P < 0.05). DIC-treated groups exhibited a more stable community structure, especially in the peptide-amended group. Microbial interactions likely aided C. jejuni survival in DIC groups with casein hydrolysates. Methanocorpusculum, Phascolarctobacterium, and Campylobacter formed a core microbial community in both DIC-treated and non-treated groups. DIC altered co-occurrence patterns among core members and differentiated taxa in abundance in acid and peptide-DIC treated groups, changing negative relationships to positive ones (Spearman's Correlation, P < 0.05). Variations in polypeptide composition affected metabolite abundance, notably impacting the urea cycle in Campylobacter and Clostridiaceae. DIC shifted communal energy metabolism in microbiota on casein sources.

CONCLUSION

Campylobacter's adaptability to the deaminase inhibitor indicates reliance on the microbial community and their metabolic products, showcasing its metabolic versatility.

Enhancing nutrient efficiency through optimizing protein levels in lambs: Involvement of gastrointestinal microbiota

Improving the nutrient utilization efficiency of ruminants is of utmost significance for both economic and environmental benefits. Optimizing dietary protein levels represents a key nutritional strategy to enhance ruminant growth performance and reduce nitrogen emissions. In a 63-day experiment, 24 healthy Hulunbuir lambs (initial weight 17.1 ± 2.0 kg, 2.5 months old) were subjected to three treatments: a low-protein diet (LP; crude protein of 78.4 g/kg dry matter [DM]), a medium-protein diet (MP; crude protein of 112.0 g/kg DM), and a high-protein diet (HP; crude protein of 145.6 g/kg DM), with 8 lambs in each treatment (4 males and 4 females). Lambs in the MP treatment presented greater daily weight gain and feed conversion ratio than those in the HP treatment (P < 0.05, quadratically). Compared with the LP treatment, the MP treatment resulted in greater crude protein digestibility (P < 0.001, quadratically) and acid detergent fiber digestibility (P = 0.022, quadratically). In the serum, the urea nitrogen level increased quadratically with increasing dietary protein levels (P < 0.001), while the LP treatment exerted the highest concentrations of glutamate, glycine, alanine, and histidine (P < 0.05, quadratically). The ammonia nitrogen concentrations in the rumen and colon increased quadratically with increase in dietary protein levels (P < 0.05). The HP treatment increased the molar concentrations of isobutyrate and isovalerate in the rumen and colon (P < 0.05, quadratically). In contrast, the LP treatment decreased the molar proportion of acetate (P = 0.007, quadratically) and increased the molar proportion of butyrate (P < 0.001, quadratically) in the colon. The microbial diversity and structure were significantly altered by dietary protein level intervention across all gastrointestinal regions. The rumen of the MP treatment was enriched with fiber-degrading bacteria Fibrobacter_succeinogenes and starch-degrading bacteria Selenomonas_ruminantium. The colon in the LP treatment harbored microbial biomarkers including Escherichia spp. and Lactobacillus amylovorus, and the colon in the MP treatment was characterized by the enrichment of Solibacillus_cecembensis. These findings suggest that the MP diet with a crude protein content of 112.0 g/kg DM improved the growth performance and nutrient efficiency of lambs, which was achieved via the involvement of the gastrointestinal microbiota.

Ensiling characteristics, in vitro digestibility and bacterial community structure of mulberry leaf silage with or without the addition of cellulase, protease, and starch

Objective

This study aimed to investigate the effects of cellulase, protease, and starch on the fermentation quality, in vitro digestibility, and microbial community of mulberry leaf silage after 30d of ensiling.

Methods

Mulberry leaves (376 g/kg dry matter (DM)) were ensiled with four experimental treatments: i) CON, no additives; ii) CEL, added cellulase (120 U/g fresh matter [FM]); iii) CPR, added cellulase (120 U/g FM) and protease (50 U/g FM); and iv) CPS, added cellulase (120 U/g FM), protease (50 U/g FM), and starch (2% FM).

Results

All treatments with additives improved fermentation quality, showing higher DM (353 ~ 378 vs. 341 g/kg DM), lactic acid (LA) content (51.6 ~ 64.6 vs. 40.2 g/kg DM), lactic acid bacteria (LAB) counts (7.63 ~ 7.73 vs. 7.49 log10 CFU /g of FM), along with lower pH values (4.29 ~ 4.60 vs. 5.09), and DM losses (124 ~ 130 vs. 134 g/kg DM) compared to the CON group. All the additive treated groups showed higher in vitro digestibility of DM (698 ~ 720 vs. 618 g/kg DM), in vitro digestibility of NDF (395 ~ 412 vs. 336 g/kg DM), and ADF (277 ~ 298 vs. 232 g/kg DM) than CON. Among all the groups, the CPS group exhibited the highest DM content (378 g/kg DM), LA content (64.6 g/kg DM) and LAB counts (7.73 log10 CFU /g of FM), with the lowest pH value (4.29) and DM losses (124 g/kg DM). Additionally, the additive treatments increased abundance of bacteria like Firmicutes and Enteroccocus, while reducing Proteobacteria abundance, and resulted in lower diversity and richness of the microbial community. Specifically, CPR and CPS silages showed increased Pediococcus and decreased Enterobacter compared to CON and CEL, and CPS silage had a relatively high abundance of favorable Bacteroidota. Furthermore, the CPS silage exhibited upregulated genetic functions, energy and lipid metabolism, as well as metabolism of cofactors and vitamins compared to the other groups.

Conclusion

The combined application of cellulase, protease, and starch effectively improved the fermentation quality, in vitro digestibility, and microbial community of mulberry leaf silage over the 30-day ensiling period.

Hermetia illucens Larvae Meal Enhances Immune Response by Improving Serum Immunoglobulin, Intestinal Barrier and Gut Microbiota of Sichuan White Geese After Avian Influenza Vaccination

Hermetia illucens Larvae Meal (HILM) has been observed to enhance growth performance and immune function, yet the effects and mechanisms in geese remain less understood. Experiment I included 64 Sichuan White Geese to investigate the optimal additive amount of HILM in diet, and experiment II included 32 Sichuan White Geese to access serum immunoglobulin, spleen immune-related genes, intestinal morphology and gut microbiota at the optimal additive amount of HILM. The results showed that the addition of 1% HILM significantly increased the ADG of Sichuan White Geese (p < 0.05), serum H5-R14 and H7-R4 strain titer at 33 d (p < 0.01) and H5-R13 strain titer (p < 0.05) at 40 d, which is the optimal dose of this trial. Experiment II revealed that the 1% HILM significantly increased serum IgG, IgG1, IgG2a, IgG3 and complement C3 (p < 0.05) and the mRNA expressions of IL-6 (p < 0.05) and CD4 (p < 0.01) in the spleen. The intestinal morphology was improved, and the secretion of SIgA and mRNA expression of Occludin in the jejunum were significantly increased (p < 0.05). Additionally, the abundance of Campilobacterota, Barnesiellaceae and Barnesiella was significantly decreased (p < 0.05), while the abundance of Lactobacillaceae was significantly increased (p < 0.05). This research provides new insights into the use of HILM in geese production.

Gut bacteria facilitate leaf beetles in adapting to dietary specialization by enhancing larval fitness

Dietary specialization between insect stages can reduce intraspecific food competition. The involvement of gut bacteria and the mechanisms underlying this phenomenon received limited attention. Plagiodera versicolora is a pest harming Salicaceae trees. Here, we confirmed dietary specialization in P. versicolora, wherein adults prefer new leaves, while larvae predominantly consume mature leaves when both types are available. We demonstrated the larval preference for mature leaves confers ecological advantages by promoting growth, development and immunity and this advantage is contingent upon the presence of gut bacteria. Gut microbiota in larvae revealed a significant enrichment of Pantoea when feeding new leaves, with P. anthophila exhibiting the most pronounced inhibitory effect on larval development. Further exploration identified specific metabolites, such as Tyrosyl-valine, with higher content in new leaves, which serve as substrates for the entomopathogenic gut bacterium to facilitate its proliferation. This study provides a fresh perspective on the ecological role of gut bacteria.

Improving the growth and intestinal colonization of Escherichia coli Nissle 1917 by strengthening its oligopeptides importation ability

Escherichia coli Nissle 1917 (EcN), the probiotic featured with well-established safety in different host, is emerging as a favored chassis for the construction of engineered probiotics for disease treatment. However, limited by the low intestinal colonization ability of EcN, repeated administration is required to maximize the health benefits of the EcN-derived engineered probiotics. Here, using fecal metabolites as "metabolites pool", we developed a metabolomic strategy to characterize the comprehensive metabolic profile of EcN. Compared with Prevotella copri DSM 18205 (P. copri), one of the dominant microbes in gut flora, EcN exhibited minor growth advantage under the fecal metabolites-containing condition for its lower metabolic capability towards fecal metabolites. Further study indicated that EcN lacked the ability to import the oligopeptides containing more than two amino acids. The shortage of oligopeptides-derived amino acids might limit the growth of EcN by restricting its purine metabolism. Assisted with the bioinformatic and qRT-PCR analyses, we identified a tripeptides-specific importer Pc-OPT in P. copri, which was mainly distributed in genera Prevotella and Bacteroides. Overexpression of Pc-OPT improved the tripeptides importation of EcN and promoted its growth and intestinal colonization. Notably, 16S rRNA gene amplicon sequencing results indicated that strengthening the oligopeptides importation ability of EcN might promote its intestinal colonization by adjusting the gut microbial composition. Our study reveals that the growth and intestinal colonization of EcN is limited by its insufficient oligopeptides importation and paves road for promoting the efficacy of the EcN-derived synthetic probiotics by improving their intestinal colonization ability.

Intestinal Lactobacillus murinus-derived small RNAs target porcine polyamine metabolism

Gut microbiota plays a vital role in host metabolism; however, the influence of gut microbes on polyamine metabolism is unknown. Here, we found germ-free models possess elevated polyamine levels in the colon. Mechanistically, intestinal Lactobacillus murinus-derived small RNAs in extracellular vesicles down-regulate host polyamine metabolism by targeting the expression of enzymes in polyamine metabolism. In addition, Lactobacillus murinus delays recovery of dextran sodium sulfate-induced colitis by reducing polyamine levels in mice. Notably, a decline in the abundance of small RNAs was observed in the colon of mice with colorectal cancer (CRC) and human CRC specimens, accompanied by elevated polyamine levels. Collectively, our study identifies a specific underlying mechanism used by intestinal microbiota to modulate host polyamine metabolism, which provides potential intervention for the treatment of polyamine-associated diseases.

Pathway and Production Differences in Branched-Chain Hydroxy Acids as Bioactive Metabolites in Limosilactobacillus fermentum, Ligilactobacillus salivarius, and Latilactobacillus sakei

Branched-chain hydroxy acids (BCHAs) as bioactive metabolites of Lactobacillaceae include 2-hydroxy isovaleric acid (HIVA), 2-hydroxy isocaproic acid (HICA), and 2-hydroxy-3-methyl isovaleric acid (HMVA). Combining targeted and untargeted metabolomics, this study elucidates differences in extracellular BCHA production in Limosilactobacillus fermentum, Ligilactobacillus salivarius, and Latilactobacillus sakei alongside comparing comprehensive metabolic changes. Through targeted metabolomics, BCHA production among 38 strains exhibited strain specificity, except for L. sakei, which showed significantly lower BCHA production. Explaining the lower production in L. sakei, which lacks the branched-chain amino acid (BCAA)-utilizing pathway, comparison of BCHA production by precursor reaction revealed that the pathway utilizing BCAAs is more dominant than the pathway utilizing pyruvate. Expanding upon the targeted approach, untargeted metabolomics revealed the effects of the reaction compound on other metabolic pathways besides BCHAs. Metabolism alterations induced by BCAA reactions varied among species. Significant differences were observed in glycine, serine, and threonine metabolism, pyruvate metabolism, butanoate metabolism, and galactose metabolism (p < 0.05). These results emphasize the importance of the synergy between fermentation strains and substrates in influencing nutritional components of fermented foods. By uncovering novel aspects of BCAA metabolism pathways, this study could inform the selection of fermentation strains and support the targeted production of BCHAs.

Breed-Driven Microbiome Heterogeneity Regulates Intestinal Stem Cell Proliferation via Lactobacillus-Lactate-GPR81 Signaling

Genetically lean and obese individuals have distinct intestinal microbiota and function. However, the underlying mechanisms of the microbiome heterogeneity and its regulation on epithelial function such as intestinal stem cell (ISC) fate remain unclear. Employing pigs of genetically distinct breeds (obese Meishan and lean Yorkshire), this study reveals transcriptome-wide variations in microbial ecology of the jejunum, characterized by enrichment of active Lactobacillus species, notably the predominant Lactobacillus amylovorus (L. amylovorus), and lactate metabolism network in obese breeds. The L. amylovorus-dominant heterogeneity is paralleled with epithelial functionality difference as reflected by highly expressed GPR81, more proliferative ISCs and activated Wnt/β-catenin signaling. Experiments using in-house developed porcine jejunal organoids prove that live L. amylovorus and its metabolite lactate promote intestinal organoid growth. Mechanistically, L. amylovorus and lactate activate Wnt/β-catenin signaling in a GPR81-dependent manner to promote ISC-mediated epithelial proliferation. However, heat-killed L. amylovorus fail to cause these changes. These findings uncover a previously underrepresented role of L. amylovorus in regulating jejunal stem cells via Lactobacillus-lactate-GPR81 axis, a key mechanism bridging breed-driven intestinal microbiome heterogeneity with ISC fate. Thus, results from this study provide new insights into the role of gut microbiome and stem cell interactions in maintaining intestinal homeostasis.

Mucin alleviates colonic barrier dysfunction by promoting spermine accumulation through enhanced arginine metabolism in Limosilactobacillus mucosae

Dietary fiber deprivation is linked to probiotic extinction, mucus barrier dysbiosis, and the overgrowth of mucin-degrading bacteria. However, whether and how mucin could rescue fiber deprivation-induced intestinal barrier defects remains largely unexplored. Here, we sought to investigate the potential role and mechanism by which exogenous mucin maintains the gut barrier function. The results showed that dietary mucin alleviated fiber deprivation-induced disruption of colonic barrier integrity and reduced spermine production in vivo. Importantly, we highlighted that microbial-derived spermine production, but not host-produced spermine, increased significantly after mucin supplementation, with a positive association with upgraded colonic Lactobacillus abundance. After employing an in vitro model, the microbial-derived spermine was consistently dominated by both mucin and Lactobacillus spp. Furthermore, Limosilactobacillus mucosae was identified as an essential spermine-producing Lactobacillus spp., and this isolated strain was responsible for spermine accumulation, especially after adhering to mucin in vitro. Specifically, the mucin-supplemented bacterial supernatant of Limosilactobacillus mucosae was verified to promote intestinal barrier functions through the increased spermine production with a dependence on enhanced arginine metabolism. Overall, these findings collectively provide evidence that mucin-modulated microbial arginine metabolism bridged the interplay between microbes and gut barrier function, illustrating possible implications for host gut health.

IMPORTANCE

Microbial metabolites like short-chain fatty acids produced by dietary fiber fermentation have been demonstrated to have beneficial effects on intestinal health. However, it is essential to acknowledge that certain amino acids entering the colon can be metabolized by microorganisms to produce polyamines. The polyamines can promote the renewal of intestinal epithelial cell and maintain host-microbe homeostasis. Our study highlighted the specific enrichment by mucin on promoting the arginine metabolism in Limosilactobacillus mucosae to produce spermine, suggesting that microbial-derived polyamines support a significant enhancement on the goblet cell proliferation and barrier function.

Dose-Responsive Effects of Iron Supplementation on the Gut Microbiota in Middle-Aged Women

Oral iron supplementation is the first-line treatment for addressing iron deficiency, a concern particularly relevant to women who are susceptible to sub-optimal iron levels. Nevertheless, the impact of iron supplementation on the gut microbiota of middle-aged women remains unclear. To investigate the association between iron supplementation and the gut microbiota, healthy females aged 40-65 years (n = 56, BMI = 23 ± 2.6 kg/m2) were retrospectively analyzed from the Alberta's Tomorrow Project. Fecal samples along with various lifestyle, diet, and health questionnaires were obtained. The gut microbiota was assessed by 16S rRNA sequencing. Individuals were matched by age and BMI and classified as either taking no iron supplement, a low-dose iron supplement (6-10 mg iron/day), or high-dose iron (>100 mg/day). Compositional and functional analyses of microbiome data in relation to iron supplementation were investigated using various bioinformatics tools. Results revealed that iron supplementation had a dose-dependent effect on microbial communities. Elevated iron intake (>100 mg) was associated with an augmentation of Proteobacteria and a reduction in various taxa, including Akkermansia, Butyricicoccus, Verrucomicrobia, Ruminococcus, Alistipes, and Faecalibacterium. Metagenomic prediction further suggested the upregulation of iron acquisition and siderophore biosynthesis following high iron intake. In conclusion, adequate iron levels are essential for the overall health and wellbeing of women through their various life stages. Our findings offer insights into the complex relationships between iron supplementation and the gut microbiota in middle-aged women and underscore the significance of iron dosage in maintaining optimal gut health.

A hydrolyzed casein diet promotes Ngn3 controlling enteroendocrine cell differentiation to increase gastrointestinal motility in mice

Gut hormones are produced by enteroendocrine cells (EECs) found along the intestinal epithelium, and these cells play a crucial role in regulating intestinal function, nutrient absorption and food intake. A hydrolyzed casein diet has been reported to promote the secretion of gut hormones through the regulation of EEC development, but the underlying mechanism remains unclear. Therefore, this study was conducted to investigate whether the hydrolyzed casein diet can regulate EEC differentiation by employing mouse and organoid models. Mice were fed diets containing either casein (casein group) or hydrolyzed casein (hydrolyzed casein group) as the sole protein source. The hydrolyzed casein diet upregulated the expression of transcription factors, induced EEC differentiation, increased fasting serum ghrelin concentrations and promoted gastrointestinal (GI) motility in the duodenum compared to the casein diet. Interestingly, these differences could be abolished when there is addition of antibiotics to the drinking water, suggesting a significant role of gut microbiota in the hydrolyzed casein-mediated EEC function. Further investigation showed that the hydrolyzed casein diet led to reduced microbial diversity, especially the abundance of Akkermansia muciniphila (A. muciniphila) on the duodenal mucosa. In contrast, gavage with A. muciniphila impaired EEC differentiation through attenuated neurog3 transcription factor (Ngn3) expression, mediated through the promotion of Notch signaling. Moreover, pasteurized A. muciniphila showed similar effects to enter organoids in vitro. Overall, we found that a hydrolyzed casein diet reduced the abundance of A. muciniphila and promoted Ngn3 controlling EEC differentiation and this pathway is associated with increased GI motility in mice. The findings provide new insights into the role of hydrolyzed casein in gut transit and guidelines for using hydrolyzed casein in safe formula milk.

The Fecal Redox Potential in Healthy and Diarrheal Pigs and Their Correlation with Microbiota

The redox potential plays a critical role in sustaining the stability of gut microbiota. This study measured the fecal redox potential in healthy and diarrheal pigs using direct and dilution methods and investigated their correlation with microbiota. The results showed that the fluctuations in the redox potential of healthy pig feces were consistent using two different methods and the two methods are equivalent based on an equivalence test. The redox potential was positively correlated with the number of fungi and negatively related to the total bacteria. The relative or absolute abundances of many bacteria at the phyla and genus levels were associated with redox potential. In diarrheal pigs, the potentiometric trends of the two methods demonstrated an opposing pattern and the correlation with total bacteria was reversed. Precipitously elevated redox potential was detected post-diarrhea using dilution methods. The absolute abundance of Escherichia-Shigella and Fuurnierella was positively correlated with redox potential, while both relative and absolute abundances of Limosilactobacillus were positively correlated. These results suggest that both methods are suitable for detecting gut redox potential in healthy pigs, while the dilution method is more suitable for diarrheal pigs. The findings on the correlation of Limosilactobacillus, Prevotella, and Escherichia-Shigella with redox potential offer novel insights for targeted modulation of intestinal health.

General media over enrichment media supports growth of Campylobacter jejuni and maintains poultry cecal microbiota enabling translatable in vitro microbial interaction experiments

AIM

This study aimed to assess the suitability of two media types, Bolton enrichment broth (BEB) and anaerobic dilution solution (ADS), in replicating the poultry cecal environment to investigate metabolic interactions and Campylobacter presence within poultry ceca.

METHODS

Using an anaerobic in vitro poultry cecal model, cecal contents (free of culturable Campylobacter) were diluted in BEB and ADS, inoculated with 105 CFU of Campylobacter jejuni, and incubated for 48 h at 42°C under microaerophilic conditions. Samples were collected at 0, 24, and 48 h. Genomic DNA was extracted, amplified, and sequenced on Illumina MiSeq platform. Data underwent analysis within QIIME2-2021.11, including alpha and beta diversity assessments, ANOVA, ADONIS, ANCOM, and Bradford assay for protein concentration.

RESULTS

ADS supported a more diverse microbial population than BEB, influencing C. jejuni presence. ANCOM highlighted dominant genera in BEB (Lactobacillus and Campylobacter) and affirmed C. jejuni growth in ADS. Core microbiota analysis revealed unique associations with each media type, while the Bradford assay indicated ADS consistently yielded more uniform microbial growth.

CONCLUSIONS

ADS was identified as a preferred diluent for faithfully replicating cecal microbial changes in the presence of Campylobacter.

Host-microbiota interaction in intestinal stem cell homeostasis

Intestinal stem cells (ISCs) play a pivotal role in gut physiology by governing intestinal epithelium renewal through the precise regulation of proliferation and differentiation. The gut microbiota interacts closely with the epithelium through myriad of actions, including immune and metabolic interactions, which translate into tight connections between microbial activity and ISC function. Given the diverse functions of the gut microbiota in affecting the metabolism of macronutrients and micronutrients, dietary nutrients exert pronounced effects on host-microbiota interactions and, consequently, the ISC fate. Therefore, understanding the intricate host-microbiota interaction in regulating ISC homeostasis is imperative for improving gut health. Here, we review recent advances in understanding host-microbiota immune and metabolic interactions that shape ISC function, such as the role of pattern-recognition receptors and microbial metabolites, including lactate and indole metabolites. Additionally, the diverse regulatory effects of the microbiota on dietary nutrients, including proteins, carbohydrates, vitamins, and minerals (e.g. iron and zinc), are thoroughly explored in relation to their impact on ISCs. Thus, we highlight the multifaceted mechanisms governing host-microbiota interactions in ISC homeostasis. Insights gained from this review provide strategies for the development of dietary or microbiota-based interventions to foster gut health.

Strategies for applying probiotics in the antibiotic management of Clostridioides difficile infection

The vital role of probiotics in the food field has been widely recognized, and at the same time, probiotics are gradually exhibiting surprising effects in the field of nutraceuticals, especially in regulating gut inflammation and the nutritional environment. As a dietary supplement in clinical nutrition, the coadministration of probiotics with antibiotics model has been applied to prevent intestinal infections caused by Clostridioides difficile. However, the mechanism behind this "bacteria-drug combination" model remains unclear. In particular, the selection of specific probiotic strains, the order of probiotics or antibiotics, and the time interval of coadministration are key issues that need to be further explored and clarified. Here, we focus on the issues mentioned above and give reasonable opinions, mainly including: (1) probiotics are safer and more effective when they intervene after antibiotics have been used; (2) the choice of the time interval between coadministration should be based on the metabolism of antibiotics in the host, differences in probiotic strains, the baseline ecological environment of the host's intestine, and the host immune level; in addition, the selection of the coadministration regime should also take into account factors such as the antibiotic sensitivity of probiotics and dosage of probiotics; and (3) by encapsulating probiotics, combining probiotics with prebiotics, and developing next-generation probiotics (NGPs) and postbiotic formulations, we can provide a more reasonable reference for this type of "bacteria-drug combination" model, and also provide targeted guidance for the application of probiotic dietary supplements in the antibiotic management of C. difficile infection.

Exploring the effects of Qijiao Shengbai capsule on leukopenic mice from the perspective of intestinbased on metabolomics and 16S rRNA sequencing

Qijiao Shengbai capsule (QJSB) is formulated according to the traditional Chinese medicine formula, its function is to nourish Qi and blood, improve the body's immunity. Leukopenia has been treated with it in clinical settings. However, the mechanism of leukopenia from the perspective of intestinal tract has not been reported. This study combined metabolomics and 16S rRNA sequencing technologies to investigate the mechanism of QJSB on leukopenia from the intestine. As a result of cyclophosphamide induction in mice, the results demonstrated that QJSB may greatly increase the quantity of peripheral leukocytes (including neutrophils). Meanwhile, QJSB had a restorative effect on the colon of leukopenic mice; it also increased the level of IL-2, IL-6 and G-CSF in the intestine, further enhancing the immunity and hematopoietic function of mice. Metabolic studies showed that QJSB altered 27 metabolites, most notably amino acid metabolism. In addition, QJSB had a positive regulatory effect on the intestinal microbiota, and could alter community composition by improving the diversity and abundance of the intestinal microbial, which mainly involved 6 related bacterial groups, and primarily regulates three associated SCFAs (acetic acid, butyrate acid and valeric acid). Therefore, this study suggests that QJSB can improve hematopoietic function, enhance the immune system, relieve leucopenia and improve the gut in leucopenic mice by modulating metabolic response pathways, fecal metabolites and intestinal microbiota.

Regulation of serotonin production by specific microbes from piglet gut

BACKGROUND

Serotonin is an important signaling molecule that regulates secretory and sensory functions in the gut. Gut microbiota has been demonstrated to affect serotonin synthesis in rodent models. However, how gut microbes regulate intestinal serotonin production in piglets remains vague. To investigate the relationship between microbiota and serotonin specifically in the colon, microbial composition and serotonin concentration were analyzed in ileum-cannulated piglets subjected to antibiotic infusion from the ileum when comparing with saline infusion. Microbes that correlated positively with serotonin production were isolated from piglet colon and were further used to investigate the regulation mechanisms on serotonin production in IPEC-J2 and a putative enterochromaffin cell line RIN-14B cells.

RESULTS

Antibiotic infusion increased quantities of Lactobacillus amylovorus (LA) that positively correlated with increased serotonin concentrations in the colon, while no effects observed for Limosilactobacillus reuteri (LR). To understand how microbes regulate serotonin, representative strains of LA, LR, and Streptococcus alactolyticus (SA, enriched in feces from prior observation) were selected for cell culture studies. Compared to the control group, LA, LR and SA supernatants significantly up-regulated tryptophan hydroxylase 1 (TPH1) expression and promoted serotonin production in IPEC-J2 cells, while in RIN-14B cells only LA exerted similar action. To investigate potential mechanisms mediated by microbe-derived molecules, microbial metabolites including lactate, acetate, glutamine, and γ-aminobutyric acid were selected for cell treatment based on computational and metabolite profiling in bacterial supernatant. Among these metabolites, acetate upregulated the expression of free fatty acid receptor 3 and TPH1 while downregulated indoleamine 2,3-dioxygenase 1. Similar effects were also recapitulated when treating the cells with AR420626, an agonist targeting free fatty acid receptor 3.

CONCLUSIONS

Overall, these results suggest that Lactobacillus amylovorus showed a positive correlation with serotonin production in the pig gut and exhibited a remarkable ability to regulate serotonin production in cell cultures. These findings provide evidence that microbial metabolites mediate the dialogue between microbes and host, which reveals a potential approach using microbial manipulation to regulate intestinal serotonin biosynthesis.

Effect of whole foods on the microbial production of tryptophan-derived aryl hydrocarbon receptor agonists in growing pigs

Effects of whole foods on the microbial production of tryptophan-derived aryl hydrocarbon receptor (AhR) ligands in the intestine were investigated in a pig model. Ileal digesta and faeces of pigs after feeding of eighteen different foods were analyzed. Indole, indole-3-propionic acid, indole-3-acetic acid, indole-3-lactic acid, kynurenine, tryptamine, and indole-3-aldehyde were identified in ileal digesta, which were also identified in faeces but at higher concentrations except indole-3-lactic acid, together with skatole, oxindole, serotonin, and indoleacrylic acid. The panel of tryptophan catabolites in ileal digesta and faeces varied across different foods. Eggs induced the highest overall concentration of catabolites in ileal digesta dominated by indole. Amaranth induced the highest overall concentration of catabolites in faeces dominated by skatole. Using a reporter cell line, we observed many faecal samples but not ileal samples retained AhR activity. Collectively, these findings contribute to food selection targeting AhR ligands production from dietary tryptophan in the intestine.

Maturation of the gut metabolome during the first year of life in humans

The gut microbiota is involved in the production of numerous metabolites that maintain host wellbeing. The assembly of the gut microbiome is highly dynamic, and influenced by many postnatal factors, moreover, little is known about the development of the gut metabolome. We showed that geography has an important influence on the microbiome dynamics in the first year of life based on two independent cohorts from China and Sweden. Major compositional differences since birth were the high relative abundance of Bacteroides in the Swedish cohort and Streptococcus in the Chinese cohort. We analyzed the development of the fecal metabolome in the first year of life in the Chinese cohort. Lipid metabolism, especially acylcarnitines and bile acids, was the most abundant metabolic pathway in the newborn gut. Delivery mode and feeding induced particular differences in the gut metabolome since birth. In contrast to C-section newborns, medium- and long-chain acylcarnitines were abundant at newborn age only in vaginally delivered infants, associated by the presence of bacteria such as Bacteroides vulgatus and Parabacteroides merdae. Our data provide a basis for understanding the maturation of the fecal metabolome and the metabolic role of gut microbiota in infancy.