Hydrogen sulfide toxicity in the gut environment: Meta-analysis of sulfate-reducing and lactic acid bacteria in inflammatory processes

Dynamics and metabolic effects of intestinal gases in healthy humans

Many living beings use exogenous and/or endogenous gases to attain evolutionary benefits. We make a comprehensive assessment of one of the major gaseous reservoirs in the human body, i.e., the bowel, providing extensive data that may serve as reference for future studies. We assess the intestinal gases in healthy humans, including their volume, composition, source and local distribution in proximal as well as distal gut. We analyse each one of the most abundant intestinal gases including nitrogen, oxygen, nitric oxide, carbon dioxide, methane, hydrogen, hydrogen sulfide, sulfur dioxide and cyanide. For every gas, we describe diffusive patterns, active trans-barrier transport dynamics, chemical properties, intra-/extra-intestinal metabolic effects mediated by intracellular, extracellular, paracrine and distant actions. Further, we highlight the local and systemic roles of gasotransmitters, i.e., signalling gaseous molecules that can freely diffuse through the intestinal cellular membranes. Yet, we provide testable hypotheses concerning the still unknown effects of some intestinal gases on the myenteric and submucosal neurons.

Comparison of microbial communities and the profile of sulfate-reducing bacteria in patients with ulcerative colitis and their association with bowel diseases: a pilot study

Considerable evidence has accumulated regarding the molecular relationship between gut microbiota (GM) composition and the onset (clinical presentation and prognosis of ulcerative colitis (UC)). In addition, it is well documented that short-chain fatty acid (SCFA)-producing bacteria may play a fundamental role in maintaining an anti-inflammatory intestinal homeostasis, but sulfate- and sulfite reducing bacteria may be responsible for the production of toxic metabolites, such as hydrogen sulfide and acetate. Hence, the present study aimed to assess the GM composition - focusing on sulfate-reducing bacteria (SRB) - in patients with severe, severe-active and moderate UC. Each one of the six enrolled patients provided two stool samples in the following way: one sample was cultivated in a modified SRB-medium before 16S rRNA sequencing and the other was not cultivated. Comparative phylogenetic analysis was conducted on each sample. Percentage of detected gut microbial genera showed considerable variation based on the patients' disease severity and cultivation in the SRB medium. In detail, samples without cultivation from patients with moderate UC showed a high abundance of the genera Bacteroides, Bifidobacterium and Ruminococcus, but after SRB cultivation, the dominant genera were Bacteroides, Klebsiella and Bilophila. On the other hand, before SRB cultivation, the main represented genera in patients with severe UC were Escherichia-Shigella, Proteus, Methanothermobacter and Methanobacterium. However, after incubation in the SRB medium Bacteroides, Proteus, Alistipes and Lachnoclostridium were predominant. Information regarding GM compositional changes in UC patients may aid the development of novel therapeutic strategies (e.g., probiotic preparations containing specific bacterial strains) to counteract the mechanisms of virulence of harmful bacteria and the subsequent inflammatory response that is closely related to the pathogenesis of inflammatory bowel diseases.

Listeria monocytogenes utilizes glutathione and limited inorganic sulfur compounds as sources of essential cysteine

Listeria monocytogenes (Lm) is a Gram-positive facultative intracellular pathogen that leads a biphasic lifecycle, transitioning its metabolism and selectively inducing virulence genes when it encounters mammalian hosts. Virulence gene expression is controlled by the master virulence regulator PrfA, which is allosterically activated by the host- and bacterially derived glutathione (GSH). The amino acid cysteine is the rate-limiting substrate for GSH synthesis in bacteria and is essential for bacterial growth. Unlike many bacteria, Lm is auxotrophic for cysteine and must import exogenous cysteine for growth and virulence. GSH is enriched in the host cytoplasm, and previous work suggests that Lm utilizes exogenous GSH for PrfA activation. Despite these observations, the import mechanism(s) for GSH remains elusive. Analysis of known GSH importers predicted a homologous importer in Lm comprised of the Ctp ABC transporter and the OppDF ATPases of the Opp oligopeptide importer. Here, we demonstrated that the Ctp complex is a high-affinity GSH/GSSG importer that is required for Lm growth at physiologically relevant concentrations. Furthermore, we demonstrated that OppDF is required for GSH/GSSG import in an Opp-independent manner. These data support a model where Ctp and OppDF form a unique complex for GSH/GSSG import that supports growth and pathogenesis. In addition, we show that Lm utilizes the inorganic sulfur sources thiosulfate and H2S for growth in a CysK-dependent manner in the absence of other cysteine sources. These findings suggest a pathoadaptive role for partial cysteine auxotrophy in Lm, where locally high GSH/GSSG or inorganic sulfur concentrations may signal arrival to distinct host niches.

Impact of Reactive Sulfur Species on Entamoeba histolytica: Modulating Viability, Motility, and Biofilm Degradation Capacity

Reactive sulfur species (RSS) like hydrogen sulfide (H2S) and cysteine persulfide (Cys-SSH) emerged as key signaling molecules with diverse physiological roles in the body, depending on their concentration and the cellular environment. While it is known that H2S and Cys-SSH are produced by both colonocytes and by the gut microbiota through sulfur metabolism, it remains unknown how these RSS affect amebiasis caused by Entamoeba histolytica, a parasitic protozoan that can be present in the human gastrointestinal tract. This study investigates H2S and Cys-SSH's impact on E. histolytica physiology and explores potential therapeutic implications. Exposing trophozoites to the H2S donor, sodium sulfide (Na2S), or to Cys-SSH led to rapid cytotoxicity. A proteomic analysis of Cys-SSH-challenged trophozoites resulted in the identification of >500 S-sulfurated proteins, which are involved in diverse cellular processes. Functional assessments revealed inhibited protein synthesis, altered cytoskeletal dynamics, and reduced motility in trophozoites treated with Cys-SSH. Notably, cysteine proteases (CPs) were significantly inhibited by S-sulfuration, affecting their bacterial biofilm degradation capacity. Immunofluorescence microscopy confirmed alterations in actin dynamics, corroborating the proteomic findings. Thus, our study reveals how RSS perturbs critical cellular functions in E. histolytica, potentially influencing its pathogenicity and interactions within the gut microbiota. Understanding these molecular mechanisms offers novel insights into amebiasis pathogenesis and unveils potential therapeutic avenues targeting RSS-mediated modifications in parasitic infections.

Beyond butyrate: microbial fiber metabolism supporting colonic epithelial homeostasis

Human gut bacteria produce metabolites that support energy and carbon metabolism of colonic epithelial cells. While butyrate is commonly considered the primary fuel, it alone cannot meet all the carbon requirements for cellular synthetic functions. Glucose, delivered via circulation or microbial metabolism, serves as a universal carbon source for synthetic processes like DNA, RNA, protein, and lipid production. Detailed knowledge of epithelial carbon and energy metabolism is particularly relevant for epithelial regeneration in digestive and metabolic diseases, such as inflammatory bowel disease and type 2 diabetes. Here, we review the production and role of different colonic microbial metabolites in energy and carbon metabolism of colonocytes, also critically evaluating the common perception that butyrate is the preferred fuel.

The sulfur microbial diet and risk of nonalcoholic fatty liver disease: a prospective gene-diet study from the UK Biobank

BACKGROUND

The gut microbiota is closely related to liver diseases. The dietary pattern associated with sulfur-metabolizing bacteria in stool has been found to influence intestinal health.

OBJECTIVE

We aimed to investigate whether consuming the sulfur microbial diet is associated with nonalcoholic fatty liver disease (NAFLD).

METHODS

We included 143,918 participants of European descent from the UK Biobank. Information on serving sizes used per diet component was recorded by an online 24-h dietary assessment tool (Oxford WebQ). The total sulfur microbial diet score was constructed by summing the product of β-coefficients and corresponding serving sizes. NAFLD was ascertained using hospital inpatient and death records. Cox proportional hazard models were used to estimate the adjusted hazard ratio (HR) and 95% confidence interval (CI). Mediation analyses were used to investigate underlying mediators including body mass index, waist circumference, glucose, triglyceride, urate, and C-reactive protein. A polygenic risk score for NAFLD was constructed and stratified to assess whether the association is modified by genetic predisposition.

RESULTS

After a median follow-up of 11.7 y (interquartile range: 11.3-12.5 y), we documented 1540 incident cases of NAFLD. After adjustment for covariates, we observed an overall J-shaped relationship between the sulfur microbial diet and risk of NAFLD. Those in the highest quartile of sulfur microbial diet score had a 46% increased risk of NAFLD [HRQ4vsQ1 (95% CI): 1.46 (1.26, 1.69)]. We also found that this association is partly mediated by metabolic disorders and systemic inflammation. In addition, the positive association was stronger among individuals at higher genetic risk for NAFLD (Pinteraction = 0.044).

CONCLUSIONS

The sulfur microbial diet had adverse associations with incident NAFLD, particularly in those at a higher genetic risk. Our study may provide evidence on the role of sulfur-metabolizing bacteria in the diet-NAFLD association.

Gut bacteriome in inflammatory bowel disease: An update on recent advances

Inflammatory bowel diseases (IBD) are chronic inflammatory gut disorders, majorly classified as ulcerative colitis and Crohn's disease. The complex, multifactorial etiopathogenesis of IBD involves genetic predisposition, environmental cues, aberrant mucosal immune response and a disturbed gut microbiota. Epidemiological trends, studies in gnotobiotic mice models and genome-wide association studies, identifying genes involved in microbial handling, together mount evidence in support of the gut microbiota playing a pivotal role in IBD pathogenesis. Both Crohn's disease and ulcerative colitis are characterized by severe dysbiosis of the gut microbiome, marked by an expansion of detrimental taxa and concomitant depletion of beneficial members. IBD is characterized by reduction in abundances of bacterial genera involved in production of short-chain fatty acids, bio-transformations of bile acids and synthesis of indole-based tryptophan compounds such as Faecalibacterium, Ruminococcus, Coprococcus, Dorea, Parabacteroides, Eubacterium, Oscillibacter and Prevotella and elevation in members of phyla Proteobacteria and Actinobacteria. This imbalance not only results in exaggerated immune signaling towards the microbial antigens, but also results in an altered metabolomic milieu that triggers additional inflammatory cascades. The present review provides insights into the bacterial dysbiosis observed across different intestinal sites and their metabolomic imprints participating in IBD.

Hydrogen sulfide responsive nanoplatforms: Novel gas responsive drug delivery carriers for biomedical applications

Hydrogen sulfide (H2S) is a toxic, essential gas used in various biological and physical processes and has been the subject of many targeted studies on its role as a new gas transmitter. These studies have mainly focused on the production and pharmacological side effects caused by H2S. Therefore, effective strategies to remove H2S has become a key research topic. Furthermore, the development of novel nanoplatforms has provided new tools for the targeted removal of H2S. This paper was performed to review the association between H2S and disease, related H2S inhibitory drugs, as well as H2S responsive nanoplatforms (HRNs). This review first analyzed the role of H2S in multiple tissues and conditions. Second, common drugs used to eliminate H2S, as well as their potential for combination with anticancer agents, were summarized. Not only the existing studies on HRNs, but also the inhibition H2S combined with different therapeutic methods were both sorted out in this review. Furthermore, this review provided in-depth analysis of the potential of HRNs about treatment or detection in detail. Finally, potential challenges of HRNs were proposed. This study demonstrates the excellent potential of HRNs for biomedical applications.

Randomized controlled trial comparing the impacts of Saccharomyces boulardii and Lactobacillus rhamnosus OF44 on intestinal flora in cerebral palsy rats: insights into inflammation biomarkers and depression-like behaviors

Background

Cerebral palsy (CP) is a unique neurological disorder which adversely affects motion. Cytokines and gut microbial composition contribute to CP and other diseases, such as reproductive tract inflammation and bone loss. Importantly, Saccharomyces boulardii (S. boulardii) reduces the degree of inflammation and improves overall health status. As our previous study showed that Lactobacillus rhamnosus (L. rhamnosus) OF44, a selected strain of gut bacteria originally used to treat reproductive tract inflammation and bone loss, has effects similar to that of S. boulardii, we decided to use L. rhamnosus OF44 on CP rats. Validation of the effects of L. rhamnosus OF44 on CP adds to its confirmed effects in treating osteoporosis and reproductive tract microbiota disorders, increasing its potential as a probiotic. The purpose of this was to ascertain whether L. rhamnosus OF44 can alleviate the symptoms of CP.

Methods

CP rat models were created through left carotid artery ligation. Following this, 100-day old CP rats were exposed to L. rhamnosus OF44, S. boulardii, or normal saline gastric gavage daily for 28 days. Grouping of the rats is determined randomly. Before and after the gavage, behavioral experiments were conducted and the inflammation levels assessed via measurements of interleukin (IL)-1β, IL-6, IL-8, and tumor necrosis factor alpha (TNF-α) inflammatory markers. The efficacy of the outcome is measured by performing statistical analysis like the t-test on the data to see its significance. Additionally, variations inside gut microbiome were evaluated via 16S ribosomal RNA sequencing.

Results

Before intervention, CP rats failed to exhibit depression-like behavior (P=0.6). L. rhamnosus OF44 treatment significantly reduced the level of IL-6 (P=4.8e-05), S. boulardii treatment significantly reduced the level of TNF-α (P=0.04). In addition, both treatments altered the composition and complexity of the gut microbiome.

Conclusions

Our results indicated that L. rhamnosus OF44 has potential in alleviating inflammation and altering the gut microbial composition in CP, and that it has the potential to clinically treat CP. There are some limitations of this study. For example, dietary differences and their effects on gastrointestinal dysfunction are not considered in this study, and only two behavioral experiments were used.

Desulfovibrio vulgaris interacts with novel gut epithelial immune receptor LRRC19 and exacerbates colitis

BACKGROUND

The overgrowth of Desulfovibrio, an inflammation promoting flagellated bacteria, has been found in ulcerative colitis (UC) patients. However, the molecular mechanism in promoting colitis remains unestablished.

METHODS

The relative abundance Desulfovibrio vulgaris (D. vulgaris) in stool samples of UC patients was detected. Mice were treated with dextran sulfate sodium to induce colitis with or without administration of D. vulgaris or D. vulgaris flagellin (DVF), and the severity of colitis and the leucine-rich repeat containing 19 (LRRC19) signaling were assessed. The interaction between DVF and LRRC19 was identified by surface plasmon resonance and intestinal organoid culture. Lrrc19-/- and Tlr5-/- mice were used to investigate the indispensable role of LRRC19. Finally, the blockade of DVF-LRRC19 interaction was selected through virtual screening and the efficacy in colitis was assessed.

RESULTS

D. vulgaris was enriched in fecal samples of UC patients and was correlated with the disease severity. D. vulgaris or DVF treatment significantly exacerbated colitis in germ-free mice and conventional mice. Mechanistically, DVF could interact with LRRC19 (rather than TLR5) in colitis mice and organoids, and then induce the production of pro-inflammatory cytokines. Lrrc19 knockdown blunted the severity of colitis. Furthermore, typhaneoside, a blockade of binding interfaces, blocked DVF-LRRC19 interaction and dramatically ameliorated DVF-induced colitis.

CONCLUSIONS

D. vulgaris could promote colitis through DVF-LRRC19 interaction. Targeting DVF-LRRC19 interaction might be a new therapeutic strategy for UC therapy. Video Abstract.

Noxious ramifications of cosmetic pollutants on gastrointestinal microbiome: A pathway to neurological disorders

On exposure to cosmetic pollutants, gastrointestinal dysbiosis, which is characterised by a disturbance in the gut microbiota, has come into focus as a possible contributor to the occurrence of neurotoxic consequences. It is normal practice to use personal care products that include parabens, phthalates, sulphates, triclosans/triclocarbans and micro/nano plastics. These substances have been found in a variety of bodily fluids and tissues, demonstrating their systemic dispersion. Being exposed to these cosmetic pollutants has been linked in recent research to neurotoxicity, including cognitive decline and neurodevelopmental problems. A vital part of sustaining gut health and general well-being is the gut flora. Increased intestinal permeability, persistent inflammation, and impaired metabolism may result from disruption of the gut microbial environment, which may in turn contribute to neurotoxicity. The link between gastrointestinal dysbiosis and the neurotoxic effects brought on by cosmetic pollutants may be explained by a number of processes, primarily the gut-brain axis. For the purpose of creating preventative and therapeutic measures, it is crucial to comprehend the intricate interactions involving cosmetic pollutants, gastrointestinal dysbiosis, and neurotoxicity. This review provides an in-depth understanding of the various hazardous cosmetic pollutants and its potential role in the occurrence of neurological disorders via gastrointestinal dysbiosis, providing insights into various described and hypothetical mechanisms regarding the complex toxic effects of these industrial pollutants.

Supplementation with a high-glucose drink stimulates anti-tumor immune responses to glioblastoma via gut microbiota modulation

A high-sugar diet induces lifestyle-associated metabolic diseases, such as obesity and diabetes, which may underlie the pro-tumor effects of a high-sugar diet. We supply GL261 syngeneic glioblastoma (GBM) mice with a short-term high-glucose drink (HGD) and find an increased survival rate with no evidence of metabolic disease. Modulation of the gut microbiota through HGD supplementation is critical for enhancing the anti-tumor immune response. Single-cell RNA sequencing shows that gut microbiota modulation by HGD supplementation increases the T cell-mediated anti-tumor immune response in GBM mice. We find that the cytotoxic CD4+ T cell population in GBM is increased due to synergy with anti-programmed cell death protein 1 (anti-PD-1) immune checkpoint inhibitors, but this effect depends upon HGD supplementation. Thus, we determine that HGD supplementation enhances anti-tumor immune responses in GBM mice through gut microbiota modulation and suggest that the role of HGD supplementation in GBM should be re-examined.

Disease-specific loss of microbial cross-feeding interactions in the human gut

Many gut microorganisms critical to human health rely on nutrients produced by each other for survival; however, these cross-feeding interactions are still challenging to quantify and remain poorly characterized. Here, we introduce a Metabolite Exchange Score (MES) to quantify those interactions. Using metabolic models of prokaryotic metagenome-assembled genomes from over 1600 individuals, MES allows us to identify and rank metabolic interactions that are significantly affected by a loss of cross-feeding partners in 10 out of 11 diseases. When applied to a Crohn's disease case-control study, our approach identifies a lack of species with the ability to consume hydrogen sulfide as the main distinguishing microbiome feature of disease. We propose that our conceptual framework will help prioritize in-depth analyses, experiments and clinical targets, and that targeting the restoration of microbial cross-feeding interactions is a promising mechanism-informed strategy to reconstruct a healthy gut ecosystem.

Listeria monocytogenes utilizes glutathione and limited inorganic sulfur compounds as a source of essential L-cysteine

Listeria monocytogenes ( Lm ) is a Gram-positive facultative intracellular pathogen that leads a biphasic lifecycle, transitioning its metabolism and selectively inducing virulence genes when it encounters mammalian hosts. Virulence gene expression is controlled by the master virulence regulator PrfA, which is allosterically activated by host- and bacterially-derived glutathione (GSH). The amino acid L-cysteine is the rate-limiting substrate for GSH synthesis in bacteria and is essential for bacterial growth. Unlike many bacteria, Lm is auxotrophic for L-cysteine and must import exogenous cysteine for growth and virulence. GSH is enriched in the host cytoplasm, and previous work suggests that Lm utilizes exogenous GSH for PrfA activation. Despite these observations, the import mechanism(s) for GSH remains elusive. Analysis of known GSH importers predicted a homologous importer in Lm comprised of the Ctp ABC transporter and the OppDF ATPases of the Opp oligopeptide importer. Here, we demonstrated that the Ctp complex is a high-affinity GSH/GSSG importer that is required for Lm growth at physiologically relevant concentrations. Further, we demonstrated that OppDF are required for GSH/GSSG import in an Opp-independent manner. These data support a model where Ctp and OppDF form a unique complex for GSH/GSSG import that supports growth and pathogenesis. Additionally, we show that Lm utilizes the inorganic sulfur sources thiosulfate and H 2 S for growth in a CysK-dependent manner in the absence of other L-cysteine sources. These findings suggest a pathoadaptive role for partial cysteine auxotrophy in Lm , where locally high GSH/GSSG or inorganic sulfur concentrations may signal arrival to distinct host niches.

Biofilms and beyond: a comprehensive review of the impact of Sulphate Reducing Bacteria on steel corrosion

Sulphate-reducing bacteria (SRB) are known to cause severe corrosion of steel structures in various industries, resulting in significant economic and environmental consequences. This review paper critically examines the impact of SRB-induced corrosion on steel, including the formation of SRB biofilms, the effect on different types of steel, and the various models developed to investigate this phenomenon. The role of environmental factors in SRB-induced corrosion, molecular techniques for studying SRBs, and strategies for mitigating corrosion are discussed. Additionally, the sustainability implications of SRB-induced corrosion and the potential use of alternative materials were explored. By examining the current state of knowledge on this topic, this review aims to provide a comprehensive understanding of the impact of SRB-induced corrosion on steel and identify opportunities for further research and development.

Hydrogel-encapsulation to enhance bacterial diagnosis of colon inflammation

Bacteria can be genetically programmed to sense and report the presence of disease biomarkers in the gastrointestinal (GI) tract. However, diagnostic bacteria are typically delivered via oral administration of liquid cultures, resulting in poor survival and high dispersal in vivo. These limitations confound recovery and analysis of engineered bacteria from GI or stool samples. Here, we demonstrate that encapsulating bacteria inside of alginate core-shell particles enables robust survival, containment, and diagnostic function in vivo. We demonstrate these benefits by encapsulating a strain engineered to report the presence of the biomarker thiosulfate via fluorescent protein expression in order to diagnose dextran sodium sulfate-induced colitis in rats. Hydrogel-encapsulated bacteria engineered to sense and respond to physiological stimuli should enable minimally invasive monitoring of a wide range of diseases and have applications as next-generation smart therapeutics.

Chondroitin sulfate supplementation improves clinical outcomes in a murine model of necrotizing enterocolitis

Necrotizing enterocolitis (NEC) continues to be a devastating disease in preterm neonates and has a paucity of medical management options. Chondroitin sulfate (CS) is a naturally occurring glycosaminoglycan (GAG) in human breast milk (HM) and has been shown to reduce inflammation. We hypothesized that supplementation with CS in an experimental NEC model would alter microbial diversity, favorably alter the cytokine profile, and (like other sulfur compounds) improve outcomes in experimental NEC via the eNOS pathway. NEC was induced in 5-day-old pups. Six groups were studied (n = 9-15/group): (1) WT breastfed and (2) Formula fed controls, (3) WT NEC, (4) WT NEC + CS, (5) eNOS KO (knockout) NEC, and (6) eNOS KO NEC + CS. Pups were monitored for clinical sickness score and weights. On postnatal day 9, the pups were killed. Stool was collected from rectum and microbiome analysis was done with 16 s rRNA sequencing. Intestinal segments were examined histologically using a well-established injury scoring system and segments were homogenized and analyzed for cytokine profile. Data were analyzed using GraphPad Prism with p < 0.05 considered significant. CS supplementation in formula improved experimental NEC outcomes when compared to NEC alone. CS supplementation resulted in similar improvement in NEC in both the WT and eNOS KO mice. CS supplementation did not result in microbial changes when compared to NEC alone. Our data suggest that although CS supplementation improved outcomes in NEC, this protection is not conferred via the eNOS pathway or alteration of microbial diversity. CS therapy in NEC does improve the intestinal cytokine profile and further experiments will explore the mechanistic role of CS in altering immune pathways in this disease.

Integrated analysis of the transcriptome and its interaction with the metabolome in metabolic associated fatty liver disease: Gut microbiome signatures, correlation networks, and effect of PNPLA3 genotype

Interactions between communities of the gut microbiome and with the host could affect the onset and progression of metabolic associated fatty liver disease (MAFLD), and can be useful as new diagnostic and prognostic biomarkers. In this study, we performed a multi-omics approach to unravel gut microbiome signatures from 32 biopsy-proven patients (10 simple steatosis -SS- and 22 steatohepatitis -SH-) and 19 healthy volunteers (HV). Human and microbial transcripts were differentially identified between groups (MAFLD vs. HV/SH vs. SS), and analyzed for weighted correlation networks together with previously detected metabolites from the same set of samples. We observed that expression of Desulfobacteraceae bacterium, methanogenic archaea, Mushu phage, opportunistic pathogenic fungi Fusarium proliferatum and Candida sorbophila, protozoa Blastocystis spp. and Fonticula alba were upregulated in MAFLD and SH. Desulfobacteraceae bacterium and Mushu phage were hub species in the onset of MAFLD, whereas the activity of Fonticula alba, Faecalibacterium prausnitzii, and Mushu phage act as key regulators of the progression to SH. A combination of clinical, metabolomic, and transcriptomic parameters showed the highest predictive capacity for MAFLD and SH (AUC = 0.96). In conclusion, faecal microbiome markers from several community members contribute to the switch in signatures characteristic of MAFLD and its progression towards SH.

Sulfur-Element containing metabolic pathways in human health and crosstalk with the microbiome

In humans, methionine derived from dietary proteins is necessary for cellular homeostasis and regeneration of sulfur containing pathways, which produce inorganic sulfur species (ISS) along with essential organic sulfur compounds (OSC). In recent years, inorganic sulfur species have gained attention as key players in the crosstalk of human health and the gut microbiome. Endogenously, ISS includes hydrogen sulfide (H2S), sulfite (SO32-), thiosulfate (S2O32-), and sulfate (SO42-), which are produced by enzymes in the transsulfuration and sulfur oxidation pathways. Additionally, sulfate-reducing bacteria (SRB) in the gut lumen are notable H2S producers which can contribute to the ISS pools of the human host. In this review, we will focus on the systemic effects of sulfur in biological pathways, describe the contrasting mechanisms of sulfurylation versus phosphorylation on the hydroxyl of serine/threonine and tyrosine residues of proteins in post-translational modifications, and the role of the gut microbiome in human sulfur metabolism.

NADH and NADPH peroxidases as antioxidant defense mechanisms in intestinal sulfate-reducing bacteria

Animal and human feces typically include intestinal sulfate-reducing bacteria (SRB). Hydrogen sulfide and acetate are the end products of their dissimilatory sulfate reduction and may create a synergistic effect. Here, we report NADH and NADPH peroxidase activities from intestinal SRB Desulfomicrobium orale and Desulfovibrio piger. We sought to compare enzymatic activities under the influence of various temperature and pH regimes, as well as to carry out kinetic analyses of enzymatic reaction rates, maximum amounts of the reaction product, reaction times, maximum rates of the enzyme reactions, and Michaelis constants in cell-free extracts of intestinal SRB, D. piger Vib-7, and D. orale Rod-9, collected from exponential and stationary growth phases. The optimal temperature (35 °C) and pH (7.0) for both enzyme's activity were determined. The difference in trends of Michaelis constants (Km) during exponential and stationary phases are noticeable between D. piger Vib-7 and D. orale Rod-9; D. orale Rod-9 showed much higher Km (the exception is NADH peroxidase of D. piger Vib-7: 1.42 ± 0.11 mM) during the both monitored phases. Studies of the NADH and NADPH peroxidases-as putative antioxidant defense systems of intestinal SRB and detailed data on the kinetic properties of this enzyme, as expressed by the decomposition of hydrogen peroxide-could be important for clarifying evolutionary mechanisms of antioxidant defense systems, their etiological role in the process of dissimilatory sulfate reduction, and their possible role in the development of bowel diseases.

Role of Hydrogen Sulfide in Inflammatory Bowel Disease

Hydrogen sulfide (H2S), originally known as toxic gas, has now attracted attention as one of the gasotransmitters involved in many reactions in the human body. H2S has been assumed to play a role in the pathogenesis of many chronic diseases, of which the exact pathogenesis remains unknown. One of them is inflammatory bowel disease (IBD), a chronic intestinal disease subclassified as Crohn's disease (CD) and ulcerative colitis (UC). Any change in the amount of H2S seems to be linked to inflammation in this illness. These changes can be brought about by alterations in the microbiota, in the endogenous metabolism of H2S and in the diet. As both too little and too much H2S drive inflammation, a balanced level is needed for intestinal health. The aim of this review is to summarize the available literature published until June 2023 in order to provide an overview of the current knowledge of the connection between H2S and IBD.

Gut and oral microbiome modulate molecular and clinical markers of schizophrenia-related symptoms: A transdiagnostic, multilevel pilot study

Although increasing evidence links microbial dysbiosis with the risk for psychiatric symptoms through the microbiome-gut-brain axis (MGBA), the specific mechanisms remain poorly characterized. In a diagnostically heterogeneous group of treated psychiatric cases and nonpsychiatric controls, we characterized the gut and oral microbiome, plasma cytokines, and hippocampal inflammatory processes via proton magnetic resonance spectroscopic imaging (1H-MRSI). Using a transdiagnostic approach, these data were examined in association with schizophrenia-related symptoms measured by the Positive and Negative Syndrome Scale (PANSS). Psychiatric cases had significantly greater heterogeneity of gut alpha diversity and an enrichment of pathogenic taxa, like Veillonella and Prevotella, in the oral microbiome, which was an accurate classifier of phenotype. Cases exhibited significantly greater positive, negative, and general PANSS scores that uniquely correlated with bacterial taxa. Strong, positive correlations of bacterial taxa were also found with cytokines and hippocampal gliosis, dysmyelination, and excitatory neurotransmission. This pilot study supports the hypothesis that the MGBA influences psychiatric symptomatology in a transdiagnostic manner. The relative importance of the oral microbiome in peripheral and hippocampal inflammatory pathways was highlighted, suggesting opportunities for probiotics and oral health to diagnose and treat psychiatric conditions.

Desulfovibrio in the Gut: The Enemy within?

Desulfovibrio (DSV) are sulfate-reducing bacteria (SRB) that are ubiquitously present in the environment and as resident commensal bacteria within the human gastrointestinal tract. Though they are minor residents of the healthy gut, DSV are opportunistic pathobionts that may overgrow in the setting of various intestinal and extra-intestinal diseases. An increasing number of studies have demonstrated a positive correlation between DSV overgrowth (bloom) and various human diseases. While the relationship between DSV bloom and disease pathology has not been clearly established, mounting evidence suggests a causal role for these bacteria in disease development. As DSV are the most predominant genera of SRB in the gut, this review summarizes current knowledge regarding the relationship between DSV and a variety of diseases. In this study, we also discuss the mechanisms by which these bacteria may contribute to disease pathology.

Effects of microbial-derived biotics (meta/pharma/post-biotics) on the modulation of gut microbiome and metabolome; general aspects and emerging trends

Potential effects of metabiotics (probiotics effector molecules or signaling factors), pharmabiotics (pro-functional metabolites produced by gut microbiota (GMB)) and postbiotics (multifunctional metabolites and structural compounds of food-grade microorganisms) on GMB have been rarely reviewed. These multifunctional components have several promising capabilities for prevention, alleviation and treatment of some diseases or disorders. Correlations between these essential biotics and GMB are also very interesting and important in human health and nutrition. Furthermore, these natural bioactives are involved in modulation of the immune function, control of metabolic dysbiosis and regulation of the signaling pathways. This review discusses the potential of meta/pharma/post-biotics as new classes of pharmaceutical agents and their effective mechanisms associated with GMB-host cell to cell communications with therapeutic benefits which are important in balance and the integrity of the host microbiome. In addition, cutting-edge findings about bioinformatics /metabolomics analyses related to GMB and these essential biotics are reviewed.

Myeloid vitamin D receptor regulates Paneth cells and microbial homeostasis

Cross talk between immune cells and the intestinal crypt is critical in maintaining intestinal homeostasis. Recent studies highlight the direct impact of vitamin D receptor (VDR) signaling on intestinal and microbial homeostasis. However, the tissue-specific role of immune VDR signaling is not fully understood. Here, we generated a myeloid-specific VDR knockout (VDRΔLyz ) mouse model and used a macrophage/enteroids coculture system to examine tissue-specific VDR signaling in intestinal homeostasis. VDRΔLyz mice exhibited small intestine elongation and impaired Paneth cell in maturation and localization. Coculture of enteroids with VDR-/- macrophages increased the delocalization of Paneth cells. VDRΔLyz mice exhibited significant changes in the microbiota taxonomic and functional files, and susceptibility to Salmonella infection. Interestingly, loss of myeloid VDR impaired Wnt secretion in macrophages, thus inhibiting crypt β-catenin signaling and disrupting Paneth cell differentiation in the epithelium. Taken together, our data have demonstrated that myeloid cells regulate crypt differentiation and the microbiota in a VDR-dependent mechanism. Dysregulation of myeloid VDR led to high risks of colitis-associated diseases. Our study provided insight into the mechanism of immune/Paneth cell cross talk in regulating intestinal homeostasis.

Hydrolysis of pea protein differentially modulates its effect on iron bioaccessibility, sulfur availability, composition and activity of gut microbial communities in vitro

Both plant proteins and iron supplements can demonstrate high susceptibility to escape small intestinal digestion and absorption, hence are often present throughout colonic fermentation. Whilst colonic iron delivery may adversely affect the gut microbiota and epithelial integrity, nascent evidence suggests that pea proteins may possess beneficial prebiotic and antioxidant effects during gut fermentation. This study investigated the interaction between exogenously added iron and pea protein isolate (PPI) or pea protein hydrolysate (PPH) during in vitro gastrointestinal digestion and colonic fermentation. Results revealed that enzymatic hydrolysis mitigated the crude protein's inhibitory effects on iron solubility during small intestinal digestion. Colonic fermentation of iron-containing treatments led to an increase in iron bioaccessibility and was characterized by a loss of within-species diversity, a marked increase in members of Proteobacteria, and eradication of some species of Lactobacillaceae. Although these patterns were also observed with pea proteins, the extent of the effects differed. Only PPI displayed significantly higher levels of total short-chain fatty acids in the presence of iron, accompanied by greater abundance of Propionibacteriaceae relative to other treatments. Additionally, we provide evidence that the iron-induced changes in the gut microbiome may be associated with its effect on endogenous sulfur solubility. These findings highlight the potential trade-off between protein-induced enhancements in fortified iron bioaccessibility and effects on the gut microbiome, and the role of iron in facilitating colonic sulfur delivery.

Orally Administrable H2 S-Scavenging Metal-Organic Framework Prepared by Co-Flow Microfluidics for Comprehensive Restoration of Intestinal Milieu

Intestinal milieu disorders are strongly related to the occurrence of inflammatory bowel diseases (IBDs), which results from mucosa destruction, epithelium disruption, and tight junction (TJ) proteins loss. Excess of H₂ S in the intestinal milieu produced by the sulfate-reducing bacteria metabolism contributes to development of IBDs via epithelial barrier breakdown. Conventional interventions, such as surgery and anti-inflammatory medications, are considered not completely effective because of frequent recurrence and other complications. Herein, a novel oral delivery system, a hydroxypropyl methylcellulose acetate succinate (HPMCAS)-based polymer-coated Zr-based metal-organic framework (UiO-66) with a Cu_x -rhodamine B (CR) probe (hereinafter referred to as HUR), is produced via a co-flow microfluidic approach with the ability to reduce H₂ S levels, thus restoring the intestinal lumen milieu. HPMCAS serves as an enteric coating that exposes UiO-66@CR at the pH of the intestine but not the acidic pH of the stomach. The synthesized HUR exhibits notable therapeutic efficacy, including mucosa recovery, epithelium integrity restoration, and TJ proteins upregulation via H₂ S scavenging to protect against intestinal barrier damage and microbiome dysbiosis. Thus, HUR is verified to be a promising theranostic platform able to decrease the H₂ S content for intestinal milieu disorder treatment. The presented study therefore opens the door for further exploitation for IBDs therapy.

Sulfur content in foods and beverages and its role in human and animal metabolism: A scoping review of recent studies

Sulfur is a vital element that all living things require, being a component of proteins and other bio-organic substances. The various kinds and varieties of microbes in nature allow for the transformation of this element. It also should be emphasized that volatile sulfur compounds are typically present in food in trace amounts. Life cannot exist without sulfur, yet it also poses a potential health risk. The colon's sulfur metabolism, which is managed by eukaryotic cells, is much better understood than the S metabolism in gastrointestinal bacteria. Numerous additional microbial processes are anticipated to have an impact on the content and availability of sulfated compounds, as well as intestinal S metabolism. Hydrogen sulfide is the sulfur derivative that has attracted the most attention in relation to colonic health, but it is still unclear whether it is beneficial or harmful. Several lines of evidence suggest that sulfate-reducing bacteria or exogenous hydrogen sulfide may be the root cause of intestinal ailments, including inflammatory bowel diseases and colon cancer. Taurine serves a variety of biological and physiological purposes, including roles in inflammation and protection, additionally, low levels of taurine can be found in bodily fluids, and taurine is the primary sulfur component present in muscle tissue (serum and urine). The aim of this scoping review was to compile data from the most pertinent scientific works about S compounds' existence in food and their metabolic processes. The importance of S compounds in various food products and how these compounds can impact metabolic processes are both stressed in this paper.

Microbiome in Behcet's syndrome

This review will discuss the current understanding of the role of microbiomes in Behcet's Syndrome, their influence on immune response and disease and potential future studies.

Effects of coexposure to noise and mixture of toluene, ethylbenzene, xylene, and styrene (TEXS) on hearing loss in petrochemical workers of southern China

Many harmful factors existing simultaneously with noise are reported to induce hearing impairment, such as organic solvents. However, the existing hearing safety limits and current risk assessment for hearing loss rely on single noise exposure. It is urgent to clarify the combined effect of noise and other harmful factors on hearing loss. Petrochemical workers are always exposed to noise and organic solvents, mainly benzene, toluene, ethylbenzene, xylene, and styrene (BTEXS), while the combined effect of their coexposure on hearing remains unclear. Herein we conducted a cross-sectional survey, measuring pure-tone audiometry of 1496 petrochemical workers in southern China. Participants exposed to BTEXS were 569, 524, 156, 452, and 177 respectively. Individual cumulative noise exposure (CNE) levels and BTEXS exposure were assessed. The average CNE was 93.27 ± 4.92 dB(A)·years, and the concentrations of BTEXS were far below the occupational exposure limits of China. Logistic regression analyses showed that CNE was consistently positively associated with hearing loss (HL) and high-frequency hearing loss (HFHL) but not related to speech-frequency hearing loss (SFHL). Compared with participants in the lowest quartile of CNE, those in the highest quartile showed an OR of 5.229 (95% CI: 3.179, 8.598) for HFHL. Two-pollutant model analysis indicated that TEXS exposure was positively associated with HL (OR 1.679, 95%CI 1.086, 2.597), SFHL (OR 2.440, 95%CI 1.255, 4.744), and HFHL (OR 1.475, 95%CI 1.077, 2.020). However, no interactions were observed between CNE and TEXS coexposure on hearing loss. In our study, covariates including smoking and drinking status, body mass index (BMI), ear protection and personal protective equipment, and use of earphone/headphone were adjusted. In conclusion, coexposure to noise and low-level TEXS could induce more severe damage on hearing function than exposure to each alone, especially SFHL. Therefore, petrochemical workers simultaneously exposed to noise and TEXS, even at low-level, should be included in hearing protection programs.

Active Sulfate-Reducing Bacterial Community in the Camel Gut

The diversity and activity of sulfate-reducing bacteria (SRB) in the camel gut remains largely unexplored. An abundant SRB community has been previously revealed in the feces of Bactrian camels (Camelus bactrianus). This study aims to combine the 16S rRNA gene profiling, sulfate reduction rate (SRR) measurement with a radioactive tracer, and targeted cultivation to shed light on SRB activity in the camel gut. Fresh feces of 55 domestic Bactrian camels grazing freely on semi-arid mountain pastures in the Kosh-Agach district of the Russian Altai area were analyzed. Feces were sampled in early winter at an ambient temperature of -15 °C, which prevented possible contamination. SRR values measured with a radioactive tracer in feces were relatively high and ranged from 0.018 to 0.168 nmol S cm^-3 day^-1. The 16S rRNA gene profiles revealed the presence of Gram-negative Desulfovibrionaceae and spore-forming Desulfotomaculaceae. Targeted isolation allowed us to obtain four pure culture isolates belonging to Desulfovibrio and Desulforamulus. An active SRB community may affect the iron and copper availability in the camel intestine due to metal ions precipitation in the form of sparingly soluble sulfides. The copper-iron sulfide, chalcopyrite (CuFeS₂), was detected by X-ray diffraction in 36 out of 55 analyzed camel feces. In semi-arid areas, gypsum, like other evaporite sulfates, can be used as a solid-phase electron acceptor for sulfate reduction in the camel gastrointestinal tract.

Lactobacillus fermentum HNU312 alleviated oxidative damage and behavioural abnormalities during brain development in early life induced by chronic lead exposure

Lead exposure is a global public health safety issue that severely disrupts brain development and causes damage to the nervous system in early life. Probiotics and gut microbes have been highlighted for their critical roles in mitigating lead toxicity. However, the underlying mechanisms by which they work yet to be fully explored. Here, we designed a two-stage experiment using the probiotic Lactobacillus fermentum HNU312 (Lf312) to uncover how probiotics alleviate lead toxicity to the brain during early life. First, we explored the tolerance and adsorption of Lf312 to lead in vitro. Second, the adsorption capacity of the strain was determined and confirmed in vivo. The shotgun metagenome sequencing showed lead exposure-induced imbalance and dysfunction of the gut microbiome. In contrast, Lf312 intake significantly modulated the structure of the microbiome, increased the abundance of beneficial bacteria and short-chain fatty acids (SCFAs)-producing bacteria, and upregulated function-related metabolic pathways such as antioxidants. Notably, Lf312 enhanced the integrity of the blood-brain barrier by increasing the levels of SCFAs in the gut, alleviated inflammation in the brain, and ultimately improved anxiety-like and depression-like behaviours induced by lead exposure in mice. Subsequently, the effective mechanism was confirmed, highlighting that Lf312 worked through integrated strategies, including ionic adsorption and microbiota-gut-brain axis regulation. Collectively, this work elucidated the mechanism by which the gut microbiota mitigates the toxic effects of lead in the brain and provides preventive measures and intervention measures for brain damage due to mass lead poisoning in children.

Enhanced anaerobic treatment of sulfate-rich wastewater by electrical voltage application

Treatment of sulfate-rich wastewater with high methane recovery is a major concern due to sulfide inhibition. Here, an electrical voltage (EV) aims to enhance methanogenesis and sulfidogenesis to treat sulfate-rich wastewater. Two (control and EV-applied) reactors were operated with a gradual decrease in chemical oxygen demand (COD)/SO₄^2- ratios (CSR). EV-applied reactor (EVR) demonstrated an increase of ∼30 % in methane production and ∼40 % in sulfate removal, compared to the control till CSR of 2.0. At CSR 1.0, the control failed, while EVR still exhibited a stable performance of 50 % COD-methane recovery. Microbial community results showed that the relative abundance of sulfate-reducing bacteria in EVR was 1.5 times higher than the control. Furthermore, higher relative abundance of dissimilatory sulfate reductase (>50 %) and Ni/Fe hydrogenase (x15) genes demonstrated an improved tolerance against H₂S toxicity. This study highlights the importance of EV application by minimizing the byproduct inhibition in sulfate-rich wastewater.

Desulfovibrio fairfieldensis-Derived Outer Membrane Vesicles Damage Epithelial Barrier and Induce Inflammation and Pyroptosis in Macrophages

Sulfate-reducing bacteria Desulfovibrio fairfieldensis is an opportunistic pathogen that widely exists in the human intestine and can cause severe infectious diseases. However, the mechanisms contributing to its pathogenesis remain of great interest. In this study, we aim to investigate the outer membrane vesicles (OMVs) secreted by D. fairfieldensis and their pathogenic effect. The OMVs separated by ultracentrifugation were spherical and displayed a characteristic bilayer lipid structure observed by transmission electron microscopy, with an average hydrodynamic diameter of 75 nm measurement using the particle size analyzer. We identified 1496 and 916 proteins from D. fairfieldensis and its OMVs using label-free non-target quantitative proteomics, respectively. The 560 co-expressed proteins could participate in bacterial life activities by function prediction. The translocation protein TolB, which participates in OMVs biogenesis and transporting toxins was highly expressed in OMVs. The OMVs inhibited the expression of tight junction proteins OCCLUDIN and ZO-1 in human colonic epithelial cells (Caco-2). The OMVs decreased the cell viability of monocyte macrophages (THP-1-Mφ) and activated various inflammatory factors secretion, including interferon-γ (IFN-γ), tumor necrosis factor (TNF-α), and many interleukins. Further, we found the OMVs induced the expression of cleaved-gasdermin D, caspase-1, and c-IL-1β and caused pyroptosis in THP-1-Mφ cells. Taken together, these data reveal that the D. fairfieldensis OMVs can damage the intestinal epithelial barrier and activate intrinsic inflammation.

Genesis of fecal floatation is causally linked to gut microbial colonization in mice

The origin of fecal floatation phenomenon remains poorly understood. Following our serendipitous discovery of differences in buoyancy of feces from germ-free and conventional mice, we characterized microbial and physical properties of feces from germ-free and gut-colonized (conventional and conventionalized) mice. The gut-colonization associated differences were assessed in feces using DNA, bacterial-PCR, scanning electron microscopy, FACS, thermogravimetry and pycnometry. Based on the differences in buoyancy of feces, we developed levô in fimo test (LIFT) to distinguish sinking feces (sinkers) of germ-free mice from floating feces (floaters) of gut-colonized mice. By simultaneous tracking of microbiota densities and gut colonization kinetics in fecal transplanted mice, we provide first direct evidence of causal relationship between gut microbial colonization and fecal floatation. Rare discordance in LIFT and microbiota density indicated that enrichment of gasogenic gut colonizers may be necessary for fecal floatation. Finally, fecal metagenomics analysis of 'floaters' from conventional and syngeneic fecal transplanted mice identified colonization of > 10 gasogenic bacterial species including highly prevalent B. ovatus, an anaerobic commensal bacteria linked with flatulence and intestinal bowel diseases. The findings reported here will improve our understanding of food microbial biotransformation and gut microbial regulators of fecal floatation in human health and disease.

Possible Processes and Mechanisms of Hexachlorobenzene Decomposition by the Selected Comamonas testosteroni Bacterial Strains

Background: The bacterial destructing activity toward pesticides has been the focus of research in the last few decades. Hexachlorobenzene is included in the organochlorine pesticides group that are prohibited for use. However, large hexachlorobenzene amounts are still concentrated in the soil, stressing the relevance of research on hexachlorobenzene-destroying bacteria. Methods: The ability to destroy hexachlorobenzene by Comamonas testosteroni UCM B-400, B-401, B-213 strains was investigated and established. Bacteria were cultivated (7 days at 28 °C) in mineral Luria-Bertrani (LB) medium with three hexachlorobenzene doses: 10, 20, 50 mg/L. The hexachlorobenzene concentrations were recorded by a gas chromatography method. Results: The results showed that C. testosteroni UCM B-400, B-401 have high destructive activity toward hexachlorobenzene. The highest (50 mg/L) initial concentration decreased to 41.5 and 43.8%, respectively, for C. testosteroni UCM B-400, B-401. The unadapted C. testosteroni UCM B-213 was tolerant to hexachlorobenzene (cell titers after cultivating with 10.0, 20.0, 50.0 mg/mL were higher compared to initial titer), but had a low-destructing activity level (two times less than B-400 and B-401). Conclusions: Bacterial strains C. testosteroni UCM B-400, B-401 can be seen as a potential soil bioremediation from hexachlorobenzene pollution.

The Aurantii Fructus Immaturus flavonoid extract alleviates inflammation and modulate gut microbiota in DSS-induced colitis mice

Inflammatory bowel disease (IBD) is a chronic, relapsing immune-mediated disease that always leads to a progressive loss of intestinal function. Therefore, it is important to find potential therapeutic drugs. This study was conducted to elucidate the effect of Aurantii Fructus immaturus flavonoid extract (AFI, 8% neohesperidin, 10% naringin) on DSS-induced intestinal inflammation and the gut microbiome. To explore the mechanism of action by which AFI protects against intestinal inflammation, a total of 50 mice were randomly divided into 5 groups [CG (control group), MG (model group), AFI low dose, AFI middle dose, and AFI high dose] and received 2.5% DSS for 7 days. Then, mice in the AFI groups were orally administered different doses of AFI for 16 days. The results showed that, compared with the MG group, the food intake and body weight were increased in the AFI groups, but the water intake was lower. Additionally, AFI significantly alleviated DSS-induced colitis symptoms, including disease activity index (DAI), and colon pathological damage. The levels of IL-6, IL-1β and TNF-α in serum and colon tissue were significantly decreased. The diversity and abundance of the intestinal microbiota in the AFI group were decreased. The relative abundance of Bacteroidota was increased, and the relative abundance of Firmicutes was decreased. AFI plays an important role in alleviating DSS-induced intestinal inflammation and regulating Oscillospira, Prevotellaceae and Lachnospiraceae in the intestine at low, medium and high doses, respectively. This report is a pioneer in the assessment of AFI. This study not only demonstrated the anti-inflammatory activity of AFI but also identified the microbiota regulated by different concentrations of AFI.

The potential impact of a probiotic: Akkermansia muciniphila in the regulation of blood pressure—the current facts and evidence

Akkermansia muciniphila (A. muciniphila) is present in the human gut microbiota from infancy and gradually increases in adulthood. The potential impact of the abundance of A. muciniphila has been studied in major cardiovascular diseases including elevated blood pressure or hypertension (HTN). HTN is a major factor in premature death worldwide, and approximately 1.28 billion adults aged 30–79 years have hypertension. A. muciniphila is being considered a next-generation probiotic and though numerous studies had highlighted the positive role of A. muciniphila in lowering/controlling the HTN, however, few studies had highlighted the negative impact of increased abundance of A. muciniphila in the management of HTN. Thus, in the review, we aimed to discuss the current facts, evidence, and controversy about the role of A. muciniphila in the pathophysiology of HTN and its potential effect on HTN management/regulation, which could be beneficial in identifying the drug target for the management of HTN.

The Assessment of Dietary Organic Zinc on Zinc Homeostasis, Antioxidant Capacity, Immune Response, Glycolysis and Intestinal Microbiota in White Shrimp (Litopenaeus vannamei Boone, 1931)

This study aimed to assess dietary organic zinc on zinc homeostasis, antioxidant capacity, immune response, glycolysis and intestinal microbiota in white shrimp (Litopenaeus vannamei Boone, 1931). Six experimental diets were formulated: Control, zinc free; S120, 120 mg·kg⁻¹ zinc from ZnSO₄·7H₂O added into control diet; O30, O60, O90 and O120, 30, 60, 90 and 120 mg·kg⁻¹ zinc from Zn-proteinate added into control diet, respectively. The results showed that organic zinc significantly promoted zinc content and gene expression of ZnT1, ZIP11 and MT in the hepatopancreas and enhanced antioxidant capacity and immunity (in terms of increased activities of T-SOD, Cu/Zn SOD, PO, LZM, decreased content of MDA, upregulated expressions of GST, G6PDH, ProPO, LZM and Hemo, and increased resistance to Vibrio parahaemolyticus). Organic zinc significantly upregulated GluT1 expression in the intestine, increased glucose content of plasma and GCK, PFK and PDH activities of hepatopancreas, and decreased pyruvate content of hepatopancreas. Organic zinc improved intestinal microbiota communities, increased the abundance of potentially beneficial bacteria and decreased the abundance of potential pathogens. Inorganic zinc (S120) also had positive effects, but organic zinc (as low as O60) could achieve better effects. Overall, organic zinc had a higher bioavailability and was a more beneficial zinc resource than inorganic zinc in shrimp feeds.

Differential Gut Microbiota Compositions Related With the Severity of Major Depressive Disorder

Objective

Increasing evidence shows a close relationship between gut microbiota and major depressive disorder (MDD), but the specific mechanisms remain unknown. This study was conducted to explore differential gut microbiota compositions related to the severity of MDD.

Methods

Healthy controls (HC) (n = 131) and MDD patients (n = 130) were included. MDD patients with Hamilton Depression Rating Scale (HDRS) score <25 and ≥25 were assigned into moderate (n = 72) and severe (n = 58) MDD groups, respectively. Univariate and multivariate analyses were used to analyze the gut microbiota compositions at the genus level.

Results

Thirty-six and 27 differential genera were identified in moderate and severe MDD patients, respectively. The differential genera in moderate and severe MDD patients mainly belonged to three (Firmicutes, Actinobacteriota, and Bacteroidota) and two phyla (Firmicutes and Bacteroidota), respectively. One specific covarying network from phylum Actinobacteriota was identified in moderate MDD patients. In addition, five genera (Collinsella, Eggerthella, Alistipes, Faecalibacterium, and Flavonifractor) from the shared differential genera by two MDD groups had a fair efficacy in diagnosing MDD from HC (AUC = 0.786).

Conclusions

Our results were helpful for further exploring the role of gut microbiota in the pathogenesis of depression and developing objective diagnostic methods for MDD.

Starch and Fiber Contents of Purified Control Diets Differentially Affect Hepatic Lipid Homeostasis and Gut Microbiota Composition

Background

Interpretation of results from diet-induced-obesity (DIO) studies critically depends on control conditions. Grain-based chows are optimized for rodent nutrition but do not match the defined composition of purified diets used for DIO, severely limiting the comparability. Purified control diets are recommended but often contain high starch and only minor fiber amounts. It is unknown whether this composition leads to metabolic alterations compared with chow and whether the addition of refined fibers at the expense of starch affects these changes.

Methods

In this experiment, 6-week-old C57BL/6N mice were fed (i) a conventional purified control diet (high-starch, low-fiber; Puri-starch), (ii) an alternative, custom-made purified control diet containing pectin and inulin (medium-starch, higher-fiber; Puri-fiber), or (iii) grain-based chow for 30 weeks (N = 8–10).

Results

Puri-starch feeding resulted in significantly elevated levels of plasma insulin (p = 0.004), cholesterol (p < 0.001), and transaminases (AST p = 0.002, ALT p = 0.001), hepatic de novo lipogenesis and liver steatosis, and an altered gut microbiota composition compared with chow-fed mice. In contrast, Puri-fiber exerted only minor effects on systemic parameters and liver lipid homeostasis, and promoted a distinct gut microbiota composition.

Conclusion

Carbohydrate-rich purified diets trigger a metabolic status possibly masking pathological effects of nutrients under study, restricting its use as control condition. The addition of refined fibers is suited to create purified, yet physiological control diets for DIO research.

Islet autoantibody seroconversion in type-1 diabetes is associated with metagenome-assembled genomes in infant gut microbiomes

The immune system of some genetically susceptible children can be triggered by certain environmental factors to produce islet autoantibodies (IA) against pancreatic β cells, which greatly increases their risk for Type-1 diabetes. An environmental factor under active investigation is the gut microbiome due to its important role in immune system education. Here, we study gut metagenomes that are de-novo-assembled in 887 at-risk children in the Environmental Determinants of Diabetes in the Young (TEDDY) project. Our results reveal a small set of core protein families, present in >50% of the subjects, which account for 64% of the sequencing reads. Time-series binning generates 21,536 high-quality metagenome-assembled genomes (MAGs) from 883 species, including 176 species that hitherto have no MAG representation in previous comprehensive human microbiome surveys. IA seroconversion is positively associated with 2373 MAGs and negatively with 1549 MAGs. Comparative genomics analysis identifies lipopolysaccharides biosynthesis in Bacteroides MAGs and sulfate reduction in Anaerostipes MAGs as functional signatures of MAGs with positive IA-association. The functional signatures in the MAGs with negative IA-association include carbohydrate degradation in lactic acid bacteria MAGs and nitrate reduction in Escherichia MAGs. Overall, our results show a distinct set of gut microorganisms associated with IA seroconversion and uncovered the functional genomics signatures of these IA-associated microorganisms.

Alterations in co-abundant bacteriome in colorectal cancer and its persistence after surgery: a pilot study

There is growing interest in the role of gut microbiome in colorectal cancer (CRC), ranging from screening to disease recurrence. Our study aims to identify microbial markers characteristic of CRC and to examine if changes in bacteriome persist after surgery. Forty-nine fecal samples from 25 non-cancer (NC) individuals and 12 CRC patients, before and 6-months after surgery, were collected for analysis by bacterial 16S rRNA gene sequencing. Bacterial richness and diversity were reduced, while pro-carcinogenic bacteria such as Bacteroides fragilis and Odoribacter splanchnicus were increased in CRC patients compared to NC group. These differences were no longer observed after surgery. Comparison between pre-op and post-op CRC showed increased abundance of probiotic bacteria after surgery. Concomitantly, bacteria associated with CRC progression were observed to have increased after surgery, implying persistent dysbiosis. In addition, functional pathway predictions based on the bacterial 16S rRNA gene data showed that various pathways were differentially enriched in CRC compared to NC. Microbiome signatures characteristic of CRC comprise altered bacterial composition. Elements of these dysbiotic signatures persists even after surgery, suggesting possible field-change in remnant non-diseased colon. Future studies should involve a larger sample size with microbiome data collected at multiple time points after surgery to examine if these dysbiotic patterns truly persist and also correlate with disease outcomes.

Associations Between Disordered Microbial Metabolites and Changes of Neurotransmitters in Depressed Mice

Backgrounds

Many pieces of evidence demonstrated that there were close relationships between gut microbiota and depression. However, the specific molecular mechanisms were still unknown. Here, using targeted metabolomics, this study was conducted to explore the relationships between microbial metabolites in feces and neurotransmitters in prefrontal cortex of depressed mice.

Methods

Chronic unpredictable mild stress (CUMS) model of depression was built in this study. Targeted liquid chromatography-mass spectrometry analysis was used to detect the microbial metabolites in feces and neurotransmitters in prefrontal cortex of mice. Both univariate and multivariate statistical analyses were applied to identify the differential microbial metabolites and neurotransmitters and explore relationships between them.

Results

Ninety-eight differential microbial metabolites (mainly belonged to amino acids, fatty acids, and bile acids) and 11 differential neurotransmitters (belonged to tryptophan pathway, GABAergic pathway, and catecholaminergic pathway) were identified. Five affected amino acid-related metabolic pathways were found in depressed mice. The 19 differential microbial metabolites and 10 differential neurotransmitters were found to be significantly correlated with depressive-like behaviors. The two differential neurotransmitters (tyrosine and glutamate) and differential microbial metabolites belonged to amino acids had greater contributions to the overall correlations between microbial metabolites and neurotransmitters. In addition, the significantly decreased L-tyrosine as microbial metabolites and tyrosine as neurotransmitter had the significantly positive correlation (r = 0.681, p = 0.0009).

Conclusions

These results indicated that CUMS-induced disturbances of microbial metabolites (especially amino acids) might affect the levels of neurotransmitters in prefrontal cortex and then caused the onset of depression. Our findings could broaden the understanding of how gut microbiota was involved in the onset of depression.

A Whiff of Sulfur: One Wind a Day Keeps the Doctor Away

Reactive Sulfur Species (RSS), such as allicin from garlic or sulforaphane from broccoli, are fre-quently associated with biological activities and possible health benefits in animals and humans. Among these Organic Sulfur Compounds (OSCs) found in many plants and fungi, the Volatile Sulfur Compounds (VSCs) feature prominently, not only because of their often-pungent smell, but also because they are able to access places which solids and solutions cannot reach that easily. Indeed, inorganic RSS such as hydrogen sulfide (H₂S) and sulfur dioxide (SO₂) can be used to lit-erally fumigate entire rooms and areas. Similarly, metabolites of garlic, such as allyl methyl sulfide (AMS), are formed metabolically in humans in lower concentrations and reach the airways from inside the body as part of one’s breath. Curiously, H₂S is also formed in the gastrointestinal tract by gut bacteria, and the question of if and for which purpose this gas then crosses the barriers and enters the body is indeed a delicate matter for equally delicate studies. In any case, nature is surprisingly rich in such VSCs, as fruits (for instance, the infamous durian) demonstrate, and therefore these VSCs represent a promising group of compounds for further studies.

Immunomodulatory effects of mixed Lactobacillus plantarum on lipopolysaccharide-induced intestinal injury in mice

The intestine is the largest digestive and immune organ in the human body, with an intact intestinal mucosal barrier. Lactobacillus plantarum is an important strain of probiotics in the intestine for boosting intestinal immunity to defend against intestinal injury. In the lipopolysaccharide-induced intestinal injury model, mixed L. plantarum (L. plantarum KLDS 1.0318, L. plantarum KLDS 1.0344, and L. plantarum KLDS 1.0386) was suggested to boost intestinal immunity. In detail, compared with LPS-induced mice, mice in the mixed L. plantarum group showed significantly reduced intestine (jejunum, ileum, and colon) tissue injury, pro-inflammatory cytokine (TNF-α, IL-6 and IL-12) levels, myeloperoxidase activities, and serum D-lactate (P < 0.05) content. Moreover, the mixed L. plantarum significantly increased the number of immunocytes (CD4+ T cells, IgA plasma cells) and the expression of tight junction proteins (Claudin1 and Occludin). The results also showed that the mixed L. plantarum significantly down-regulated (P < 0.05) the intestinal protein expression of TLR4, p-IκB, and NF-κB p65. The mixed L. plantarum group increased the relative abundance of the genera, including Lactobacillus, Lachnoclostridium, and Desulfovibrio, which are related to improving the levels of SCFAs (acetic acid, butyric acid) and total bile acid (P < 0.05). Overall, these results indicated that the mixed L. plantarum had great functionality in reducing LPS-induced intestinal injury.

Diversity and distribution of sulfur metabolic genes in the human gut microbiome and their association with colorectal cancer

BACKGROUND

Recent evidence implicates microbial sulfidogenesis as a potential trigger of colorectal cancer (CRC), highlighting the need for comprehensive knowledge of sulfur metabolism within the human gut. Microbial sulfidogenesis produces genotoxic hydrogen sulfide (H₂S) in the human colon using inorganic (sulfate) and organic (taurine/cysteine/methionine) substrates; however, the majority of studies have focused on sulfate reduction using dissimilatory sulfite reductases (Dsr).

RESULTS

Here, we show that genes for microbial sulfur metabolism are more abundant and diverse than previously observed and are statistically associated with CRC. Using ~ 17,000 bacterial genomes from publicly available stool metagenomes, we studied the diversity of sulfur metabolic genes in 667 participants across different health statuses: healthy, adenoma, and carcinoma. Sulfidogenic genes were harbored by 142 bacterial genera and both organic and inorganic sulfidogenic genes were associated with carcinoma. Significantly, the anaerobic sulfite reductase (asr) genes were twice as abundant as dsr, demonstrating that Asr is likely a more important contributor to sulfate reduction in the human gut than Dsr. We identified twelve potential pathways for reductive taurine metabolism and discovered novel genera harboring these pathways. Finally, the prevalence of metabolic genes for organic sulfur indicates that these understudied substrates may be the most abundant source of microbially derived H₂S.

CONCLUSIONS

Our findings significantly expand knowledge of microbial sulfur metabolism in the human gut. We show that genes for microbial sulfur metabolism in the human gut are more prevalent than previously known, irrespective of health status (i.e., in both healthy and diseased states). Our results significantly increase the diversity of pathways and bacteria that are associated with microbial sulfur metabolism in the human gut. Overall, our results have implications for understanding the role of the human gut microbiome and its potential contributions to the pathogenesis of CRC. Video abstract.

Bacteriocin-mediated inhibition of some common pathogens by wild and mutant Lactobacillus species and in vitro amplification of bacteriocin encoding genes

Lactobacilli are the most common probiotics used in food and other industries because of their capability of producing bacteriocins. Bacteriocins are compounds that are used to kill pathogenic microorganisms. As most bacteria have become resistant to synthetic antibacterial tools, the importance of using probiotics as antibacterial agents has increased. This work was done to check the bacteriocin effect on some common pathogens and the influence of mutation on the bacteriocin activity of Lactobacilli was also investigated. Four strains were isolated, identified from meat and pickles samples via culturing methods, staining, biochemical tests, and ribotyping. Preliminary tests, including Gram staining and catalase test, were done for the confirmation of Lactobacillus species. All strains were gram-positive and catalase-negative. Antibacterial activity was checked against Pseudomonas aeruginosa, Staphylococcus aureus, Bacillus thuringiensis, Escherichia coli, and Salmonella enteritis via agar well diffusion method. The mutations were done using ethidium bromide and the influence of wild and mutants were also checked. Interestingly, mutants developed more virulence than wild ones. It was also observed that they all were sensitive to pepsin. Protein estimation was done via Bradford method. Ribotyping of GCU-W-PS1 revealed 99 % homology with Lactobacillus plantarum and GCU-W-MS1 to Lactobacillus curvatus (99 % homology). Curvacin A, sakacin P, and plantaricin A genes were also amplified using specific primers. Gene sequence showed the presence of curvacin A gene in GCU-W-MS1. It was concluded that lactic acid bacteria could be used as antibacterial tools against common pathogens.