Leuconostoc mesenteroides fermentation produces butyric acid and mediates Ffar2 to regulate blood glucose and insulin in type 1 diabetic mice

Blood metabolites mediate causal inference studies on the effect of gut microbiota on the risk of vascular calcification

BACKGROUND

Emerging evidence indicates a notable connection between gut microbiota and Vascular Calcification (VC). Gut microbiota influences various disease processes through host metabolic pathways; however, the causative link between gut microbiota and VC, along with the potential mediating role of metabolites, is still not well understood.

METHODS

We leveraged data from the largest Genome-Wide Association Studies (GWAS) concerning gut microbiota, blood metabolites, and VC. To explore the causal relationships among these variables, we conducted two-sample bidirectional Mendelian Randomization (MR) analyses. Furthermore, mediation analyses were conducted to determine if metabolites act as an intermediary in the impact of gut microbiota on VC. In addition, we recruited CKD patients for mass spectrometry and CT examination, and performed a correlation analysis between the expression of blood metabolites and VC score. Finally, we experimentally validated the effects of intermediate metabolites on VC.

RESULTS

We identified 19 positive gut microbiota species and 52 positive blood metabolites with causal effects on VC. Additionally, the onset of VC was found to induce changes in the abundance of 24 gut microbiota species and 56 metabolites. Further analyses revealed that up to 13 positive gut microbiota species regulate the expression of 20 positive metabolites. Mediation analysis suggests that the gut microbiota g_KLE1615 promotes VC by downregulating the methionine-to-phosphate ratio. Mass spectrometry results indicate that over half of the metabolites identified through MR analysis show altered expression during CKD progression. Among them, 7 metabolites were significantly associated with the progression of VC. Further in vitro experiments confirmed the inhibitory effect of the intermediate metabolite methionine on VC.

CONCLUSION

Gut microbiota and blood metabolites are causally linked to VC. These findings provide a theoretical basis for microbiome- and metabolome-based therapeutic strategies for targeting VC and enhances our comprehension of the gut-vascular axis.

Live and heat-killed Leuconostoc mesenteroides counteract the gastrointestinal dysfunction in chronic kidney disease mice through intestinal environment modulation

Probiotics are well-known therapeutic agents for managing constipation and have been used to improve chronic kidney disease (CKD) progression. However, heat-killed probiotics on CKD remain inadequately explored. This study aimed to evaluate the probiotic potential of lactic acid bacteria derived from natural sources and to investigate the effects of both live and heat-killed Leuconostoc mesenteroides (Ln.m) on renal and gastrointestinal functions in CKD mice. Ln.m was selected from acid and bile salt intolerance tests, non-hemolytic activity, and antibiotic sensitivity. CKD mice demonstrated significantly elevated blood urea nitrogen (BUN) and creatinine levels compared to control mice (p < 0.001 and p < 0.01). Treatment with live and heat-killed Ln.m significantly reduced BUN and creatinine levels in CKD mice (p < 0.01 and p < 0.05). Additionally, kidney damage observed in CKD mice compared to control mice, including glomerular necrosis, tubular dilatation, inflammation, and fibrosis, was significantly alleviated following live and heat-killed Ln.m treatments. CKD-induced gastrointestinal dysfunction was characterized by an imbalance in Firmicutes/Bacteroidota populations, increased colonic uremic toxin (p < 0.01), reduced fecal short-chain fatty acids (SCFAs) (p < 0.05), and constipation. Treatment with live and heat-killed Ln.m restored gut microbiota, decreased uremic toxin (p < 0.001), increased SCFAs (p < 0.05), and alleviated constipation. In summary, both live and heat-killed Ln.m effectively alleviated gastrointestinal dysfunction and renal damage in CKD mice, primarily through modulation of the intestinal environment. These findings highlight the therapeutic potential of live and heat-killed Ln.m as the gastrointestinal dysfunction treatment in CKD.

Non-targeted metabolomic profile of Leuconostoc mesenteroides-fermented milk reveals differentially expressed metabolites associated with electro-fermentation

BACKGROUND

Leuconostoc mesenteroides (L. mesenteroides) has known as an electrogenic probiotic bacterium. However, metabolites related to electro-fermentation in ferments of L. mesenteroides are not unveiled.

RESULT

Electrogenic L. mesenteroides fermentatively metabolized bovine milk to dense ferments with homogeneous particle-size distribution. A non-targeted metabolomics approach was performed on non-fermented and L. mesenteroides-fermented milk. A total of 917 metabolites were identified and quantified by ultra-high performance liquid chromatography (UHPLC)-tandem mass spectrometry (MS-MS). Thirteen prokaryotic metabolic pathways associated with differentially expressed metabolites (DEMs) were revealed through Koto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis. Anthranilic acid (AA) and 3-hydroxyanthranilin acid (3-HAA), potentially as electron donors, and quinolinic acid, an electron donor precursor, in the tryptophan kynurenine pathway were significantly increased in the fermented milk. Histidine, arginine, and riboflavin involved in bacterial survival or bioelectricity production were elevated after fermentation.

CONCLUSIONS

Results indicate that electrogenic L. mesenteroides can mediate electro-fermentation to transform milk to a new nutritional source which is rich in electron donors reportedly acting as antioxidants.

Microbiota transfer early after birth modulates genetic susceptibility to chronic arthritis in mice

Genetics is central to the susceptibility or resistance to autoimmunity, and mounting evidence indicates that the intestinal microbiota also plays an essential role. In murine arthritis models, short-chain fat acid supplementation reduces disease severity by modulating tryptophan-metabolizing bacteria. Common microbiota transfer methods modulate arthritis severity, however, they are not practical for chronic models such as pristane-induced arthritis (PIA). PIA-resistant (HIII) and PIA-susceptible (LIII) mice harbor diverse intestinal microbiomes, which might be implicated in their divergent susceptibility. To investigate this hypothesis, we used cross-fostering to stably transfer the microbiota. In this study, we show that extreme susceptibility to arthritis can be modulated by early microbiota transfer, with long-lasting effects. HIII and LIII pups were cross-fostered and injected with pristane after weaning. PIA severity in cross-fostered LIII mice was significantly reduced in the chronic phase. Metagenomic analyses showed that HIII and LIII microbiomes were partly shifted by cross-fostering. Microbial groups whose abundance was associated with either HIII or LIII mice presented similar composition in cross-fostered mice of the opposite strains, suggesting a role in PIA susceptibility. Identification of bacterial groups that modulate chronic arthritis will contribute novel insights on the pathogenesis of human rheumatoid arthritis and targets for replication and functional studies.

Anatomizing causal relationships between gut microbiota, plasma metabolites, and epilepsy: A mendelian randomization study

BACKGROUND

Epilepsy causes a heavy disease burden, and the gut microbiota (GM) influences the progression of epilepsy, while plasma metabolites directly or indirectly associated with GM may play a mediating role. However, the causal relationships between epilepsy, GM, and potential metabolite mediators are lack of investigation.

METHODS

Mendelian randomization (MR) analysis was applied to estimate the effects of GM and plasma metabolites on epilepsy. Genetic instruments were obtained from large-scale genome-wide meta-analysis of GM (n = 5959), plasma metabolites (n = 136,016), and epilepsy (Cases/controls = 12891/312803) of European ancestry. Epilepsy phenotypes included all epilepsy, generalized epilepsy and focal epilepsy from the Finn Gen R10 database. And two-step MR (TSMR) to discover the potential mediating metabolites.

RESULTS

In total, we found 19 gut microbial taxa to be causally associated with the risk of epilepsy, among which Omnitrophota phylum had the strongest association (OR, 2.3; P = 0.009) with promoting effect. We also identified 21 plasma metabolites associated with epilepsy, the strongest ones of which are eastotal fatty acids (OR, 1.12; P = 0.001) that exhibited a facilitating effect. We observed indirect effects of free cholesterol to total lipids ratio in large LDL in associations between Fournierella massiliensis species and epilepsy, with a mediated proportion of -3.64% (95%CI, -7.22%∼-0.06%; P = 0.046).

CONCLUSION

This study supports a causal link between Fournierella massiliensis species, free cholesterol to total lipids ratio in large LDL and epilepsy, as well as a mediating effect of free cholesterol to total lipids ratio in large LDL in epilepsy.

Anti-Obesity Effects of Leuconostoc mesenteroides 4-Fermented Lemon Peel Filtrate on HFD-Induced Obese Mice via NFκB/ PPAR-γ Pathway

Obesity is a major health problem associated with Type 2 diabetes, non-alcohol fatty liver disease (NAFLD), and atherosclerosis. Functional lactic acid bacteria-fermented products have been reported to have potential anti-obese effect. The present results revealed that Leuconostoc mesenteroides 4 (LMSS4)-fermented lemon peel filtrate slowed down the increase of body weight, and decreased liver and epididymal fat indices; it also decreased serum levels of TC (total cholesterol), TG (triglyceride), LDL-C (low-density lipoprotein cholesterol), ALT (alanine transaminase), AST (aspartate transaminase), and AKP (alkaline phosphatase), TNF-α (tumor necrosis factor-α), IFN-γ (interferon gamma), IL-1β (interleukin-1β), IL-6 (interleukin-6), and IL-10 (interleukin-10), increased the levels of HDL-C (high-density lipoprotein cholesterol), IL-4 (interleukin-4), and IL-10 (interleukin-10). Furthermore, the mRNA expression of NFκB-p65 (nuclear factor-κB p65), PPAR-γ (eroxisome proliferator-activated receptor γ), TNF-α, IL-1β, leptin, SREBP-1c (sterol regulatory element binding protein-1c), FAS (fatty acid synthase), and CEBP/α (CCAAT/enhancer binding protein α) were down-regulated, while the expression of IL-4, IκB-α (inhibitory subunit of NF Kappa B alpha), and IL-10 were upregulated after the mice were treated with LMSS4-fermented lemon filtrate; the filtrate also downregulated the protein expression of NFκB-p65 and PPAR-γ but increased the expression of IκB-α. The HPLC results found that rutin and hesperidin were the predominant constituents in both the unfermented and LMSS4-fermented lemon filtrates among the 15 constituents analyzed. In addition, chlorogenic acid, umbelliferone, byakangelicin, and oxypeucedanin hydrate were increased in the fermented lemon filtrate, in which chlorogenic acid showed the highest increase rate (83.51%). In conclusion, the anti-obesity effect of LMSS 4-fermented lemon peel filtrate was mediated via the regulation of the NFκB/PPAR-γ signaling pathway. These results could provide an experimental basis for developing new functional lemon beverages for obesity intervention.

Metabolic Insights into Urinary Stone Formation: Evidence from Mendelian Randomization, Clinical, and in vivo Studies

Introduction

The global rise in urinary stone prevalence has become a significant health and economic challenge. Linked to metabolic disorders such as obesity and diabetes, urinary stones represent a complex systemic condition that requires a comprehensive understanding of metabolic profiles for effective management.

Methods

The methodological quality of this study was evaluated in accordance with the STROBE-MR checklist. Using genome-wide association study (GWAS) data for 1,091 blood and 1,172 urine metabolites, we conducted a two-sample Mendelian randomization (MR) analysis, validated by meta-analysis, to explore metabolic influences on stone formation. Multivariable and mediation MR analyses were performed to identify independent metabolite influences and their interaction with gut microbiota and metabolism-related genes. Clinical metabolomic analysis and further animal experiments substantiated our findings.

Results

Univariable MR identified 119 blood and 63 urine metabolites associated with urinary stones, with 16 blood and 2 urine metabolites showing robust associations post-correction. Notably, mannose and 3-aminoisobutyrate emerged as independent influencers of stone formation. Mediation MR suggested these metabolites as potential mediators in the gut microbiota's influence on stone formation. Clinical urine sample analysis indicates higher mannose levels in normal renal sides than stone sides. Animal studies confirmed mannose's protective role by reducing renal calcium oxalate crystal deposition.

Conclusion

Our study establishes causal links between specific metabolites and urinary stones, shedding light on the intricate biological mechanisms of stone formation. The discovery of mannose as a protective factor opens avenues for future research and clinical applications, offering promising directions for the prevention and treatment of stones.

Assessment of Immobilized Lacticaseibacillus rhamnosus OLXAL-1 Cells on Oat Flakes for Functional Regulation of the Intestinal Microbiome in a Type-1 Diabetic Animal Model

The aim of this study was to examine the effect of free or immobilized Lacticaseibacillus rhamnosus OLXAL-1 cells on oat flakes on the gut microbiota and metabolic and inflammatory markers in a streptozotocin (STZ)-induced Type-1 Diabetes Mellitus (T1DM) animal model. Forty-eight male Wistar rats were assigned into eight groups (n = 6): healthy or diabetic animals that received either a control diet (CD and DCD), an oat-supplemented diet (OD and DOD), a diet supplemented with free L. rhamnosus OLXAL-1 cells (CFC and DFC), or a diet supplemented with immobilized L. rhamnosus OLXAL-1 cells on oat flakes (CIC and DIC). Neither L. rhamnosus OLXAL-1 nor oat supplementation led to any significant positive effects on body weight, insulin levels, plasma glucose concentrations, or lipid profile parameters. L. rhamnosus OLXAL-1 administration resulted in a rise in the relative abundances of Lactobacillus and Bifidobacterium, as well as increased levels of lactic, acetic, and butyric acids in the feces of the diabetic animals. Additionally, supplementation with oat flakes significantly reduced the microbial populations of E. coli, Enterobacteriaceae, coliforms, staphylococci, and enterococci and lowered IL-1β levels in the blood plasma of diabetic animals. These findings suggested that probiotic food-based strategies could have a potential therapeutic role in managing dysbiosis and inflammation associated with T1DM.

Momoridica charantia and fermented Momoridica charantia with Leuconostoc mesenteroides MKSR change intestinal microbial diversity indices and compositions in high-fat and high-cholesterol diet-fed C57BL/6 male mice

Introduction

This study explores the impact of 4% Momordica charantia (MC) and 4% fermented Momordica charantia (FMC) on gut microbiota and obesity-related health outcomes in male C57BL/6 mice, a model relevant to veterinary sciences for understanding metabolic and gut health disorders in animals.

Methods

Mice were assigned to four dietary regimens, including control, high-fat and high-cholesterol diet (POS), POS with 4% MC, and POS with 4% FMC (fermented with Leuconostoc mesenteroides MKSR) over 12 weeks. Fecal samples were collected for 16S rRNA sequencing to evaluate microbial diversity and composition, key factors influencing animal health.

Results

Both MC and FMC groups exhibited significant alterations in gut microbial communities, with FMC inducing a distinct shift in beta diversity indices. Changes in microbial taxa such as Bacteroidetes, Verrucomicrobia, and Firmicutes were observed, along with enhancement in the 'L-glutamate and L-glutamine biosynthesis' pathway. These shifts were associated with reduced body weight gain and liver weights.

Discussion

The findings suggest that MC and FMC have potential benefits for managing diet-induced metabolic disorders and protecting against obesity by modulating gut microbiota and improving gut metabolism.

The insights into sour flavor and organic acids in alcoholic beverages

Alcoholic beverages have developed unique flavors over millennia, with sourness playing a vital role in their sensory perception and quality. Organic acids, as crucial flavor compounds, significantly impact flavor. This paper reviews the sensory attribute of sour flavor and key organic acids in alcoholic beverages. Regarding sour flavor, research methods include both static and dynamic sensory approaches and summarize the interaction of sour flavor with aroma, taste, and mouthfeel. In addition, this review focuses on identifying key organic acids, including sample extraction, chromatography, olfactometry/taste, and mass spectrometry. The key organic acids in alcoholic beverages, such as wine, Baijiu, beer, and Huangjiu, and their primary regulatory methods are discussed. Finally, future avenues for the exploration of sour flavor and organic acids by coupling machine learning, database, sensory interactions and electroencephalography are suggested. This systematic review aims to enhance understanding and serve as a reference for further in-depth studies on alcoholic beverages.

Neurotransmitter metabolites in milk ferments of Leuconostoc mesenteroides regulate temperature-sensitive heartbeats in an ex ovo model

Accumulated evidence has supported the probiotic activity of Leuconostoc mesenteroides (L. mesenteroides) which can yield beneficial metabolites via fermentation. Here, bovine milk rich in phenylalanine（PHE) was used as a source for fermentation of L. mesenteroides. The complexes of PHE with bacterial phenylalanine hydroxylase (PheH) at two temperatures were revealed via molecular dynamics simulation. Two carbon hydrogen bonds and a Pi-Alkyl T-shaped interaction were newly formed at an active site of the PheH-PHE complex. The PheH interacted with two different hydrogen atoms in an amine of PHE via conventional hydrogen bonds at 37 °C, a temperature that accelerated the milk fermentation of L. mesenteroides. Twenty-eight metabolites including various neurotransmitters in fermented milk were identified and quantified by liquid chromatography coupled to quadrupole ion trap (Q-Trap) tandem mass spectrometry. Ex ovo injection of milk ferments into the yolk sac of chicken embryos enhanced a rising temperature-induced increase in heartbeats towards the normal resting level. The neurotransmitter-rich milk ferments hold potential for using to adjust energy metabolism, referred from heart rates, during fluctuating temperature conditions.

Effects of short-chain fatty acids on blood glucose and lipid levels in mouse models of diabetes mellitus: A systematic review and network meta-analysis

Short-chain fatty acids (SCFAs), the main metabolites of gut microbiota, have been associated with lower blood glucose and lipid levels in diabetic mice. However, a comprehensive summary and comparison of the effects of different SCFA interventions on blood glucose and lipid levels in diabetic mice is currently unavailable. This study aims to compare and rank the effects of different types of SCFAs on blood glucose and lipid levels by collecting relevant animal research. A systematic search through PubMed, Embase, Cochrane Library, and Web of Science database was conducted to identify relevant studies from inception to March 17, 2023. Both pairwise meta-analysis and Bayesian network meta-analysis were used for statistical analyses. In total, 18 relevant studies involving 5 interventions were included after screening 3793 citations and 53 full-text articles. Notably, butyrate therapy (mean difference [MD] = -4.52, 95% confidence interval [-6.29, -2.75]), acetate therapy (MD = -3.12, 95% confidence interval [-5.79, -0.46]), and propionate therapy (MD = -2.96, 95% confidence interval [-5.66, -0.26]) significantly reduced the fasting blood glucose levels compared to the control group; butyrate therapy was probably the most effective intervention, with a surface under the cumulative ranking curve (SUCRA) value of 85.5%. Additionally, acetate plus propionate therapy was probably the most effective intervention for reducing total cholesterol (SUCRA = 85.8%) or triglyceride levels (SUCRA = 88.1%). These findings underscore the potential therapeutic implications of SCFAs for addressing metabolic disorders, particularly in type 2 diabetes mellitus.

Gut feelings in the islets: The role of the gut microbiome and the FFA2 and FFA3 receptors for short chain fatty acids on β-cell function and metabolic regulation

Short-chain fatty acids (SCFAs) are biosynthesized via fermentation of polysaccharides by gastrointestinal microbiota and have been shown to have wide-reaching effects on almost all tissues, including the pancreatic islets. Historically, the effects of SCFAs have been attributed to their intracellular metabolism and function as energy sources, but the discovery of free fatty acid G protein-coupled receptors (GPCRs) in the 2000s suggested that many functional outcomes of SCFAs are receptor-mediated. The SCFA receptors FFA2/GPR43 and FFA3/GPR41 are expressed on β-cells, where they regulate glucose-dependent insulin secretion, making them attractive targets for treatment of diabetes and other metabolic disorders. Here, we provide an update on the current evidence regarding regulation of FFA2/FFA3 receptors by specific probiotic bacterial species within the gut microbiome that synthesize SCFAs. We also review the body of research regarding the FFA2- and FFA3 receptor-specific function of SCFAs on β-cells and discuss the somewhat controversial and opposing findings within these studies.

Recent advances in the use of bacterial probiotics in animal production

Animal husbandry is increasingly under pressure to meet world food demand. Thus, strategies are sought to ensure this productivity increment. The objective of this review was to gather advances in the use of bacterial probiotics in animal production. Lactobacilli correspond to the most used bacterial group, with several beneficial effects already reported and described, as well as the Enterococcus and Pediococcus genera - being the latter expressively used in aquaculture. Research on the Bifidobacterium genus is mostly focused on human health, which demonstrates great effects on blood biochemical parameters. Such results sustain the possibility of expanding its use in veterinary medicine. Other groups commonly assessed for human medicine but with prospective expansion to animal health are the genera Leuconostoc and Streptococcus, which have been demonstrating interesting effects on the prevention of viral diseases, and in dentistry, respectively. Although bacteria from the genera Bacillus and Lactococcus also have great potential for use in animal production, a complete characterization of the candidate strain must be previously made, due to the existence of pathogenic and/or spoilage variants. It is noteworthy that a growing number of studies have investigated the genus Propionibacterium, but still in very early stages. However, the hitherto excellent results endorse its application. In this way, in addition to the fact that bacterial probiotics represent a promising approach to promote productivity increase in animal production, the application of other strains than the traditionally employed genera may allow the exploitation of novel mechanisms and enlighten unexplored possibilities.

Study on Potential Differentially Expressed Genes in Idiopathic Pulmonary Fibrosis by Bioinformatics and Next-Generation Sequencing Data Analysis

Idiopathic pulmonary fibrosis (IPF) is a chronic progressive lung disease with reduced quality of life and earlier mortality, but its pathogenesis and key genes are still unclear. In this investigation, bioinformatics was used to deeply analyze the pathogenesis of IPF and related key genes, so as to investigate the potential molecular pathogenesis of IPF and provide guidance for clinical treatment. Next-generation sequencing dataset GSE213001 was obtained from Gene Expression Omnibus (GEO), and the differentially expressed genes (DEGs) were identified between IPF and normal control group. The DEGs between IPF and normal control group were screened with the DESeq2 package of R language. The Gene Ontology (GO) and REACTOME pathway enrichment analyses of the DEGs were performed. Using the g:Profiler, the function and pathway enrichment analyses of DEGs were performed. Then, a protein-protein interaction (PPI) network was constructed via the Integrated Interactions Database (IID) database. Cytoscape with Network Analyzer was used to identify the hub genes. miRNet and NetworkAnalyst databaseswereused to construct the targeted microRNAs (miRNAs), transcription factors (TFs), and small drug molecules. Finally, receiver operating characteristic (ROC) curve analysis was used to validate the hub genes. A total of 958 DEGs were screened out in this study, including 479 up regulated genes and 479 down regulated genes. Most of the DEGs were significantly enriched in response to stimulus, GPCR ligand binding, microtubule-based process, and defective GALNT3 causes HFTC. In combination with the results of the PPI network, miRNA-hub gene regulatory network and TF-hub gene regulatory network, hub genes including LRRK2, BMI1, EBP, MNDA, KBTBD7, KRT15, OTX1, TEKT4, SPAG8, and EFHC2 were selected. Cyclothiazide and rotigotinethe are predicted small drug molecules for IPF treatment. Our findings will contribute to identification of potential biomarkers and novel strategies for the treatment of IPF, and provide a novel strategy for clinical therapy.

Regular consumption of lacto-fermented vegetables has greater effects on the gut metabolome compared with the microbiome

The industrialisation of Western food systems has reduced the regular consumption of lacto-fermented vegetables (LFV). Consuming LFV may exert health benefits through the alteration of the gut microbiome, but the mechanisms involved remain unclear. To start understanding the possible benefits of LFV, we compared faecal microbial diversity and composition, as well as dietary habits between individuals who regularly consume LFV (n = 23) and those who do not (n = 24). We utilised microbial DNA amplicon sequencing (16S rRNA and ITS2) and untargeted metabolomics (LC-MS) to analyse stool samples. Study participants also provided three consecutive days of dietary data. Results show minor effects on microbiome composition; with the enrichment of a few microorganisms potentially associated with vegetable ferments, such as Leuconostoc mesenteroides and Rhodotorula mucilaginosa (P < 0.05), in LFV consumers. However, LFV consumption had greater effects on the faecal metabolome, with higher abundances of butyrate, acetate, and valerate (P < 0.05) and significantly greater metabolome diversity (P < 0.001). Overall, the observations of minor changes in the faecal microbiome and greater effects on the faecal metabolome from LFV consumption warrant further investigations on the health significance of LFV as regular components of the daily diet in humans.

Ready-To-Eat Rocket Salads as Potential Reservoir of Bacteria for the Human Microbiome

Reportedly, Western-type diets may induce the loss of key microbial taxa within the gastrointestinal microbiota, promoting the onset of noncommunicable diseases. It was hypothesized that the consumption of raw vegetables could contribute to the maintenance of the intestinal microbial community structure. In this context, we explored bacteria associated with commercial rocket salads produced through different farming practices: traditional (conventional, organic, and integrated) and vertical farming. Viable counts of mesophilic bacteria and lactic acid bacteria (LAB) were performed on plate count agar (PCA) and de Man-Rogosa-Sharpe (MRS) agar at pH 5.7, whereas metataxonomics through 16S rRNA gene sequencing was used to profile total bacteria associated with rocket salads. We found that rocket salads from vertical farming had much fewer viable bacteria and had a bacterial community structure markedly different from that of rocket salads from traditional farming. Furthermore, although α- and β-diversity analyses did not differentiate rocket samples according to farming techniques, several bacterial taxa distinguished organic and integrated from conventional farming salads, suggesting that farming practices could affect the taxonomic composition of rocket bacterial communities. LAB were isolated from only traditional farming samples and belonged to different species, which were variably distributed among samples and could be partly associated with farming practices. Finally, the INFOGEST protocol for in vitro simulation of gastrointestinal digestion revealed that several taxonomically different rocket-associated bacteria (particularly LAB) could survive gastrointestinal transit. This study suggests that commercial ready-to-eat rocket salads harbor live bacteria that possess the ability to survive gastrointestinal transit, potentially contributing to the taxonomic structure of the human gut microbiota. IMPORTANCE Western-type diets are composed of foods with a reduced amount of naturally occurring microorganisms. It was hypothesized that a microbe-depleted diet can favor the alteration of the human intestinal microbial ecosystem, therefore contributing to the onset of chronic metabolic and immune diseases currently recognized as the most significant causes of death in the developed world. Here, we studied the microorganisms that are associated with commercial ready-to-eat rocket salads produced through different farming practices. We showed that rocket salad (a widely consumed vegetal food frequently eaten raw) may be a source of lactic acid bacteria and other microbes that can survive gastrointestinal transit, potentially increasing the biodiversity of the intestinal microbiota. This deduction may be valid for virtually all vegetal foods that are consumed raw.

The protective effects of sulforaphane on high-fat diet-induced metabolic associated fatty liver disease in mice via mediating the FXR/LXRα pathway

Metabolic-associated fatty liver disease (MAFLD) is becoming the key factor in causing chronic liver disease all over the world. Sulforaphane (SFN) has been proven to be effective in alleviating many metabolic diseases, such as obesity and type 2 diabetes. In this study, C57BL/6 mice were fed a high-fat diet for 12 weeks to induce MAFLD and given SFN (10 mg per kg bw) daily. Our results showed that SFN not only improved the excessive accumulation of fat in the liver cells but also ameliorated liver and serum inflammatory and antioxidant levels. In addition, SFN can regulate bile-acid metabolism and fatty-acid synthesis by affecting their farnesoid X receptor (FXR)/liver X receptor alpha (LXRα) signaling pathway, ultimately alleviating MAFLD. Our study provides a theoretical basis for the mechanism by which SFN alleviates hepatic steatosis.

Preclinical Studies of Natural Products Targeting the Gut Microbiota: Beneficial Effects on Diabetes

Diabetes mellitus (DM) is a serious metabolic disease characterized by persistent hyperglycemia, with a continuously increasing morbidity and mortality. Although traditional treatments including insulin and oral hypoglycemic drugs maintain blood glucose levels within the normal range to a certain extent, there is an urgent need to develop new drugs that can effectively improve glucose metabolism and diabetes-related complications. Notably, accumulated evidence implicates that the gut microbiota is unbalanced in DM individuals and is involved in the physiological and pathological processes of this metabolic disease. In this review, we introduce the molecular mechanisms by which the gut microbiota contributes to the development of DM. Furthermore, we summarize the preclinical studies of bioactive natural products that exert antidiabetic effects by modulating the gut microbiota, aiming to expand the novel therapeutic strategies for DM prevention and management.

Traditional Fermented Foods from Ecuador: A Review with a Focus on Microbial Diversity

The development of early civilizations was greatly associated with populations’ ability to exploit natural resources. The development of methods for food preservation was one of the pillars for the economy of early societies. In Ecuador, food fermentation significantly contributed to social advances and fermented foods were considered exclusive to the elite or for religious ceremonies. With the advancement of the scientific research on bioprocesses, together with the implementation of novel sequencing tools for the accurate identification of microorganisms, potential health benefits and the formation of flavor and aroma compounds in fermented foods are progressively being described. This review focuses on describing traditional fermented foods from Ecuador, including cacao and coffee as well as less popular fermented foods. It is important to provide new knowledge associated with nutritional and health benefits of the traditional fermented foods.

Evidence and possible mechanisms of probiotics in the management of type 1 diabetes mellitus

Abstract

Type 1 diabetes mellitus (T1DM) is one of the most common chronic immune-mediated diseases. The prevalence is worldwide especially among children and young adults. The destruction of the pancreatic β-cells due to some abnormalities in the immune system characterizes T1DM. Considering the high burden of the disease and its impact on human health, researchers have made great efforts during the last decades; investigating the disease pathogenesis and discovering new strategies for its management. Fortunately, probiotics have been found as potential remedies for T1DM. This review aims to explore the potentialities of probiotics in managing T1DM and its complications. Based on the outcomes of human and animal studies carried out from 2016 to 2021, the review hopes to assess the effectiveness of probiotics in the prevention and treatment of T1DM and its complications. We first tried to explain the disease's pathogenesis, and highlighted the possible mechanisms involved in these potentialities of probiotics. We concluded that, probiotics can be used as possible therapeutic tools for the management of T1DM. Possible mechanisms of action of probiotics include; the modulation of the gut microbiota, the regulation of inflammation-related cytokines, the production of short chain fatty acids (SCFAs), and the regulation of GLP-1. However, we recommend further studies especially human trials should be carried out to investigate these potentialities of probiotics.

Highlights

• T1DM is highly prevalent worldwide, causing high morbidity and mortality especially among children and young adults• Gut microbiota plays a significant role in the pathogenesis of T1DM via an interconnection with the immune system• Probiotics can be used as possible therapeutic tools for the management of T1DM• Possible mechanisms of action of probiotics include the modulation of the gut microbiota, the regulation of inflammation-related cytokines, the production of SCFAs, and the regulation of GLP-1.

Analysis of Intestinal Short-Chain Fatty Acid Metabolism Profile After Probiotics and GLP-1 Treatment for Type 2 Diabetes Mellitus

Type 2 diabetes accounts for about 90% of diabetes patients, and the incidence of diabetes is on the rise as people's lifestyles change. Compared with GLP-1 treatment, probiotic treatment can directly regulate homeostasis of the host gut microbe, and thus homeostasis of its metabolites. Currently, the regulatory role of probiotics on intestinal metabolites after treatment of type 2 diabetes mellitus remains unclear. The purpose of this study was to investigate the therapeutic effect of probiotics on type 2 diabetes mellitus and its regulatory effect on short-chain fatty acids, which are metabolites of intestinal microorganisms. I collected feces from 15 patients with diabetes before treatment and 15 patients with type 2 diabetes after treatment with GLP-1 and probiotics. The abundance of short-chain fatty acids in feces was determined by GC-MS. Results Both GLP-1 and probiotics could improve the levels of blood glucose, urine glucose and BMI in patients with type 2 diabetes. After glP-1 treatment, two short-chain fatty acids (butyric acid and valerate acid) in intestine were significantly changed. Propionic acid and isovalerate were significantly changed after probiotic treatment. At the same time, KEGG signal pathway enrichment results showed that probiotics intervention mainly achieved the purpose of treating type 2 diabetes through regulating protein and carbohydrate metabolism. Taken together, our study shows changes in intestinal short-chain fatty acids after probiotics or GLP-1 treatment of type 2 diabetes, which will provide us with new insights into the mechanism of probiotics treatment of type 2 diabetes, as well as potential intervention targets for diabetes treatment.

The HDAC Inhibitor Butyrate Impairs β Cell Function and Activates the Disallowed Gene Hexokinase I

Histone deacetylase (HDAC) inhibitors such as butyrate have been reported to reduce diabetes risk and protect insulin-secreting pancreatic β cells in animal models. However, studies on insulin-secreting cells in vitro have found that butyrate treatment resulted in impaired or inappropriate insulin secretion. Our study explores the effects of butyrate on insulin secretion by BRIN BD-11 rat pancreatic β cells and examined effects on the expression of genes implicated in β cell function. Robust HDAC inhibition with 5 mM butyrate or trichostatin A for 24 h in β cells decreased basal insulin secretion and content, as well as insulin secretion in response to acute stimulation. Treatment with butyrate also increased expression of the disallowed gene hexokinase I, possibly explaining the impairment to insulin secretion, and of TXNIP, which may increase oxidative stress and β cell apoptosis. In contrast to robust HDAC inhibition (>70% after 24 h), low-dose and acute high-dose treatment with butyrate enhanced nutrient-stimulated insulin secretion. In conclusion, although protective effects of HDAC inhibition have been observed in vivo, potent HDAC inhibition impairs β cell function in vitro. The chronic low dose and acute high dose butyrate treatments may be more reflective of in vivo effects.

Effect of the administration of probiotics on the fecal microbiota of adult individuals

Probiotics have been used to ameliorate ailments by modulating gut microbiota. However, to date, the effects of probiotic supplementation on the composition of fecal microbiota in healthy adults remain obscure. In this study, nine healthy volunteers were recruited to take probiotics (a mixture of Lactobacillus casei Zhang, L. plantarum P-8, and Bifidobacterium lactis V9, 2:2:3, 1 × 1010 CFU/day) for 28 days. The fecal samples were collected at 0 and 28 days, and V4 of the 16S rRNA gene sequenced by Illumina MiSeq was used to analyze the fecal microbiota. The enterotype has been used to characterize the composition of gut microbiota. Nine adults were divided into Type P (fecal microbiota dominated by Prevotella, 4 adults) and Type B (fecal microbiota dominated by Bacteroides, 5 adults) based on an enterotype analysis. The responses of variation had been found in two enterotypes. The α-diversity was not changed significantly after the administration of probiotics in both Type P and B. However, the community structure in Type B was substantially influenced. After the administration of probiotics, Weissella and Leuconostoc were significantly higher in Type P, while Collinsella significantly increased in Type B. The different pathways involving pathogen infections were downregulated at 28 days. The Type VI secretion system and the EHEC/EPEC pathogenicity signature were downregulated in Type B and Type P, respectively.

Gut probiotic Lactobacillus rhamnosus attenuates PDE4B-mediated interleukin-6 induced by SARS-CoV-2 membrane glycoprotein

Membrane glycoprotein is the most abundant protein of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), but its role in coronavirus disease 2019 (COVID-19) has not been fully characterized. Mice intranasally inoculated with membrane glycoprotein substantially increased the interleukin (IL)-6, a hallmark of the cytokine storm, in bronchoalveolar lavage fluid (BALF), compared to mice inoculated with green fluorescent protein (GFP). The high level of IL-6 induced by membrane glycoprotein was significantly diminished in phosphodiesterase 4 (PDE4B) knockout mice, demonstrating the essential role of PDE4B in IL-6 signaling. Mycelium fermentation of Lactobacillus rhamnosus (L. rhamnosus) EH8 strain yielded butyric acid, which can down-regulate the PDE4B expression and IL-6 secretion in macrophages. Feeding mice with mycelia increased the relative abundance of commensal L. rhamnosus. Two-week supplementation of mice with L. rhamnosus plus mycelia considerably decreased membrane glycoprotein-induced PDE4B expression and IL-6 secretion. The probiotic activity of L. rhamnosus plus mycelia against membrane glycoprotein was abolished in mice treated with GLPG-0974, an antagonist of free fatty acid receptor 2 (Ffar2). Activation of Ffar2 in the gut-lung axis for down-regulation of the PDE4B-IL-6 signalling may provide targets for development of modalities including probiotics for treatment of the cytokine storm in COVID-19.

Role of Postbiotics in Diabetes Mellitus: Current Knowledge and Future Perspectives

In the last decade, the gastrointestinal microbiota has been recognised as being essential for health. Indeed, several publications have documented the suitability of probiotics, prebiotics, and symbiotics in the management of different diseases such as diabetes mellitus (DM). Advances in laboratory techniques have allowed the identification and characterisation of new biologically active molecules, referred to as “postbiotics”. Postbiotics are defined as functional bioactive compounds obtained from food-grade microorganisms that confer health benefits when administered in adequate amounts. They include cell structures, secreted molecules or metabolic by-products, and inanimate microorganisms. This heterogeneous group of molecules presents a broad range of mechanisms and may exhibit some advantages over traditional “biotics” such as probiotics and prebiotics. Owing to the growing incidence of DM worldwide and the implications of the microbiota in the disease progression, postbiotics appear to be good candidates as novel therapeutic targets. In the present review, we summarise the current knowledge about postbiotic compounds and their potential application in diabetes management. Additionally, we envision future perspectives on this topic. In summary, the results indicate that postbiotics hold promise as a potential novel therapeutic strategy for DM.

Different Reactions in Each Enterotype Depending on the Intake of Probiotic Yogurt Powder

Probiotics can be used as a nutritional strategy to improve gut homeostasis. We aimed to evaluate the intestinal microbiota profile of 18 subjects after ingestion of probiotic yogurt powder (PYP) based on enterotype. The subjects were classified into three enterotypes according to their microbial community: Bacteroides (n = 9, type B), Prevotella (n = 3, type P), and Ruminococcus (n = 6, type R). We performed controlled termination in a transient series that included a control period of three weeks before probiotic intake, PYP intake for three weeks, and a three-week washout period. Fecal microbiota composition was analyzed by sequencing the V3-V4 super variable region of 16S rRNA. Based on the Bristol stool shape scale, abnormal stool shape improved with PYP intake, and bowel movements were activated. The abundance of Faecalibacterium, Eggerthella, and Leuconostoc, which ferment and metabolize glucose, showed a strong correlation with type B Bacteroides, and glucose metabolism improvement was observed in all type B subjects. Alkaline phosphatase was significantly improved only in type B. In addition, the abundance of type B Bacteroides showed a negative correlation with that of Lactobacillus. The abundance of Streptococcus, Agathobacter, and Christensenella, which are involved in lipid metabolism, showed a strong correlation with that of type P Prevotella, and triglyceride metabolism improvement was observed in all type P subjects. The gut microbiota showed only short-term changes after PYP intake and showed resilience by returning to its original state when PYP intake was interrupted. In summary, the different responses to PYP intake may result from the different enterotypes and associated strains; therefore, the probiotic composition should be adjusted based on the individual enterotype.

Leuconostoc mesenteroides mediates an electrogenic pathway to attenuate the accumulation of abdominal fat mass induced by high fat diet

Although several electrogenic bacteria have been identified, the physiological effect of electricity generated by bacteria on host health remains elusive. We found that probiotic Leuconostoc mesenteroides (L. mesenteroides) can metabolize linoleic acid to yield electricity via an intracellular cyclophilin A-dependent pathway. Inhibition of cyclophilin A significantly abolished bacterial electricity and lowered the adhesion of L. mesenteroides to the human gut epithelial cell line. Butyrate from L. mesenteroides in the presence of linoleic acid were detectable and mediated free fatty acid receptor 2 (Ffar2) to reduce the lipid contents in differentiating 3T3-L1 adipocytes. Oral administration of L. mesenteroides plus linoleic acid remarkably reduced high-fat-diet (HFD)-induced formation of 4-hydroxy-2-nonenal (4-HNE), a reactive oxygen species (ROS) biomarker, and decreased abdominal fat mass in mice. The reduction of 4-HNE and abdominal fat mass was reversed when cyclophilin A inhibitor-pretreated bacteria were administered to mice. Our studies present a novel mechanism of reducing abdominal fat mass by electrogenic L. mesenteroides which may yield electrons to enhance colonization and sustain high amounts of butyrate to limit ROS during adipocyte differentiation.

Isolation and Identification of Potentially Pathogenic Microorganisms Associated with Dental Caries in Human Teeth Biofilms

Dental caries is attributed to the predominance of cariogenic microorganisms. Cariogenic microorganisms are pathological factors leading to acidification of the oral microenvironment, which is related to the initiation and progression of caries. The accepted cariogenic microorganism is Streptococcus mutans (S. mutans). However, studies have found that caries could occur in the absence of S. mutans. This study aimed to assess the presence of potentially cariogenic microorganisms in human teeth biofilm. The microorganisms were isolated from human mouth and freshly extracted human maxillary incisors extracted for reasons of caries. The isolates were sorted based on their acidogenic and aciduric properties, and the S. mutans was used as the reference strain. Four potentially cariogenic strains were selected. The selected strains were identified as Streptococcus salivarius (S. salivarius), Streptococcus anginosus (S. anginosus), Leuconostoc mesenteroides (L. mesenteroides), and Lactobacillus sakei (L. sakei) through morphological analysis followed by 16S rRNA gene sequence analysis. The cariogenicity of isolates was analyzed. We show, for the first time, an association between L. sakei (present in fermented food) and dental caries. The data provide useful information on the role of lactic acid bacteria from fermented foods and oral commensal streptococci in dental caries.

Production of electricity and reduction of high-fat diet-induced IL-6 by glucose fermentation of Leuconostoc mesenteroides

Electrogenic bacteria can mediate electron transfer to conserve energy and promote growth. To examine bacterial electrogenicity, an L. mesenteroides EH-1 strain was cultured in rich media in the presence and absence of 2% glucose. After 12 h incubation, glucose triggered fermentation of L. mesenteroides EH-1 to produce >10 mmol/l acetate and elicit electricity measured by voltage changes. The electricity production was mediated by glucose fermentation since pre-treatment of L. mesenteroides EH-1 with furfural, a fermentation inhibitor, completely diminished the voltage increases. The deficiency of furfural pre-treated L. mesenteroides EH-1 in electricity production can be restored by the external addition of acetate into the bacterial culture, suggesting the function of acetate as an electron donor. Oral administration of HFD-fed mice with L. mesenteroides EH-1 in the presence or absence of glucose significantly attenuated the high level of pro-inflammatory IL-6 cytokine in blood. Bacterial electricity can be elicited by fermentation. Supplementation of fermenting and electrogenic L. mesenteroides EH-1 may provide a novel approach for the reduction of pro-inflammatory IL-6 cytokine that increased in chronic inflammation, autoimmune diseases, cancers, and infections.

Mouse Abdominal Fat Depots Reduced by Butyric Acid-Producing Leuconostoc mesenteroides

The activation of peroxisome proliferator-activated rece ptor gamma (PPAR-γ) is known to induce the differentiation of adipocytes. This study aimed to investigate the probiotic effect of Leuconostoc mesenteroides (L. mesenteroides) on high-fat diet (HFD)-induced PPAR-γ activation and abdominal fat depots. Incubation of differentiated 3T3-L1 adipocytes with media of L. mesenteroides EH-1, a butyric acid-producing strain, significantly reduced the amounts of lipid droplets. The oral administration of L. mesenteroides EH-1 produced large amounts (>1 mM) of butyric acid in cecum and attenuated the HFD-induced upregulation of PPAR-γ and accumulation of abdominal fats in mice. The combination of 2% glucose with L. mesenteroides EH-1 increased the production of butyric acid and potentiated the probiotic activity of L. mesenteroides EH-1 against the formation of lipid droplets in 3T3-L1 adipocytes as well as abdominal fats in HFD-fed mice. The inhibition of free fatty acid receptor 2 (Ffar2) by its antagonist, GLPG-0974, markedly diminished the probiotic effects of L. mesenteroides EH-1 plus glucose on the suppression of HFD-induced PPAR-γ and abdominal fats. Besides demonstrating the probiotic value of L. mesenteroides EH-1, our results highlight the possible therapy targeting the butyric acid-activated Ffar2 pathway to reduce abdominal fats.

Metabolic and inflammatory functions of short-chain fatty acid receptors

FFA2 and FFA3 are receptors for short-chain fatty acids which are produced in prodigious amounts by fermentation of poorly digested carbohydrates by gut bacteria. Understanding the roles of these receptors in regulating enteroendocrine, metabolic and immune functions has developed with the production and use of novel pharmacological tools and animal models. A complex (patho)physiological scenario is now emerging in which strategic expression of FFA2 and FFA3 in key cell types and selective modulation of their signalling might regulate body weight management, energy homoeostasis and inflammatory disorders.