mSphere最新文献

{"title":"<i>In vitro</i> metabolic signaling in two intestinal bacterial isolates: glutamate-driven transcriptional and functional reprogramming in <i>Clostridium butyricum</i> and <i>Bacteroides thetaiotaomicron</i>.","authors":"Nazanin Nematzadeh Somehsaraei, Joshua Lemuel Hadi, Mohammadali Khan Mirzaei, Li Deng, Michael Gigl, Corinna Dawid, Philippe Schmitt-Kopplin, Itır Geydirici, Michael Schloter, Silvia Gschwendtner","doi":"10.1128/msphere.00190-26","DOIUrl":"10.1128/msphere.00190-26","url":null,"abstract":"<p><p>Monosodium glutamate (MSG; L-glutamate monosodium salt) is among the most widely used flavor enhancers, yet its molecular effects on gut microbial physiology remain poorly understood. Here, we examined the strain-specific transcriptomic and metabolic responses of <i>Clostridium butyricum</i> and <i>Bacteroides thetaiotaomicron</i> grown in pure anaerobic culture with 0.1% (wt/vol) MSG. Although MSG exposure was not associated with major changes in total bacterial biomass dynamics, both species showed a temporal functional reprogramming. In <i>C. butyricum</i>, MSG rapidly intensified metabolic activity to capitalize on exogenous glutamate by activating central carbon metabolism, redox-balancing pathways, and the GABA shunt, thereby collectively enhancing butyrate synthesis, a metabolite associated with gut barrier integrity, energy regulation, and anti-inflammatory signaling. On the other hand, <i>B. thetaiotaomicron</i> adopted a conservative, homeostatic response, suppressing glycan utilization and central carbon and energy metabolism, and maintaining stable SCFA production through controlled regulation that buffered against abrupt dietary perturbations. Overall, MSG functioned as a potent metabolic signal, triggering distinct adaptive strategies in two dominant gut bacteria.</p><p><strong>Importance: </strong>The impact of monosodium glutamate (MSG) as a highly consumed food additive on the gut microbiome is often overlooked, and community-level analyses reveal little change, masking distinct phenotypic responses of individual strains. By combining gene expression and metabolite profiling using two key human gut bacteria, we show that MSG is sensed as a metabolic signal. A butyrate-producing gut bacterium increases energy metabolism and butyrate production, and a fiber-degrading gut bacterium transiently moderates metabolism to maintain stable fermentation products. These differences suggest that MSG's physiological effects may depend on which bacterial groups dominate an individual's microbiome.</p>","PeriodicalId":19052,"journal":{"name":"mSphere","volume":" ","pages":"e0019026"},"PeriodicalIF":4.0,"publicationDate":"2026-08-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13508794/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148701862","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"An innovative organoid model to screen for bacteria and their metabolites that protect against inflammation-induced colonic barrier disruption.","authors":"Nicole Cady, Sophia R Meyer, Kwi Kim, Bernard C Lo, Ngai So, Grace Y Chen, Stephan P Rosshart, Yatrik M Shah, Gabriel Núñez, Jonathan Z Sexton, Thomas M Schmidt","doi":"10.1128/msphere.00926-25","DOIUrl":"10.1128/msphere.00926-25","url":null,"abstract":"<p><p>Organoids provide a useful model system to study interactions between gut microbes and the activity of host tissues, including gastrointestinal (GI) barrier function. However, most organoid models have limited capacity to mimic the physiological hypoxia experienced by the colonic epithelium <i>in vivo</i>. While oxygen is required to support respiration in the host cells, many gut microbes are anaerobes that require anoxic conditions to grow. Using an innovative anaerobe co-culture system that maintains constant oxygen concentrations on the basolateral side of colonic epithelial monolayers and anoxic conditions on the luminal side, we demonstrate that colonic monolayers derived from a primary human cell line behaved more like <i>in vivo</i> epithelia when cultivated in the co-culture system than when cultured under ambient oxygen concentrations. We then identified interactions between the colonic epithelium and a strain of <i>Bifidobacterium adolescentis</i>-an oxygen-sensitive species that is prevalent and abundant in the adult gut microbiome. Co-culturing colonic monolayers with <i>Bifidobacterium adolescentis</i> U269-1 in the anoxic apical chamber mitigated loss of the barrier function in monolayers exposed to inflammatory cytokines. We identified indole lactic acid (ILA) as one metabolite from <i>B. adolescentis</i> that provides dose-dependent protection against inflammatory cytokines. Oral administration of ILA was well tolerated in mice and provided protection against immunotherapy-induced (anti-CTLA4) colitis in female, but not male mice. Together, we demonstrated the utility of the co-culture system for screening microbes and their metabolites for interactions with the colonic epithelium, as well as advancing our understanding of interactions between bifidobacteria and host barrier function.<b>IMPORTANCE</b>The present study yielded strong evidence for the beneficial effects of <i>B. adolescentis</i> on the maintenance of colonic barrier function in an asymmetric oxygen system that mimics the colonic environment. The bifidobacterial metabolite indole lactic acid was implicated in this protection both <i>in vitro</i> and in a mouse model. We also refined and scaled the co-culture system to a 96-well plate format to provide the capacity for higher-throughput screening of microbes and microbial metabolites under physiologically relevant conditions.</p>","PeriodicalId":19052,"journal":{"name":"mSphere","volume":" ","pages":"e0092625"},"PeriodicalIF":4.0,"publicationDate":"2026-08-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13508787/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148631063","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Acquisition of a gene cluster in <i>Clostridioides difficile</i> PCR ribotype 023 strains enables xylitol utilization.","authors":"Katherine J Wozniak, Lei Pan, Duolong Zhu, Jeroen Corver, Ed J Kuijper, Wiep Klaas Smits, Robert A Britton","doi":"10.1128/msphere.00263-26","DOIUrl":"10.1128/msphere.00263-26","url":null,"abstract":"<p><p>Hundreds of ribotypes of the gastrointestinal pathogen <i>Clostridioides difficile</i> have emerged over the last three decades, yet the factors driving their emergence are poorly understood. Recently, there has been an increase in infections caused by PCR ribotype 023 (RT023) strains in Europe. We profiled the growth of seven RT023 strains in 190 unique carbon sources and found they were able to grow in xylitol, a sugar alcohol used as a food additive in humans and animals. Other ribotypes of <i>C. difficil</i>e tested (<i>n</i> = 19) displayed little to no growth in 0.5% xylitol and were growth-inhibited in higher concentrations of xylitol. Genome sequencing identified that RT023 strains acquired a putative xylitol dehydrogenase (<i>xdh</i>) gene in a mobile genetic element (MGE) that is absent from other <i>C. difficile</i> ribotypes. We created a deletion of <i>xdh</i> in the RT023 strain PRB1128 and observed poor growth in xylitol, indicating that the <i>xdh</i> is necessary for xylitol utilization. Complementation of the <i>xdh</i> mutant with a plasmid-based inducible copy of the <i>xdh</i> gene restored growth in xylitol. We performed competition assays in minibioreactor arrays (MBRAs) and observed that PRB1128 outcompeted the non-xylitol-utilizing strain CD2015 (RT027) in the presence of xylitol. These data support that the <i>xdh</i> gene within RT023 strains provides a fitness benefit for growth in xylitol. Interestingly, the chromosomal locus where the MGE inserted appears to be a hotspot for genetic insertions across clades of <i>C. difficile</i>. Together, this work improves our understanding of the molecular basis for niche adaptation of <i>C. difficile</i>.<b>IMPORTANCE</b>Genetic factors aiding in the emergence of the opportunistic pathogen <i>Clostridioides difficile</i> are poorly understood. Infections with clade 3 (PCR ribotype 023) strains causing severe disease have increased since 2008. Here, we show RT023 strains have the unique ability to utilize xylitol, a sugar alcohol used as a food additive in humans and animals, due to the presence of a xylitol dehydrogenase (<i>xdh</i>) gene within a mobile genetic element (MGE). This xylitol utilization ability confers a fitness benefit in competition against other <i>C. difficile</i> ribotypes, as well as in a fecal community <i>in vitro</i>. Research investigating the underlying genetic factors driving the physiology of <i>C. difficile</i> will improve our understanding of colonization and hypervirulence.</p>","PeriodicalId":19052,"journal":{"name":"mSphere","volume":" ","pages":"e0026326"},"PeriodicalIF":4.0,"publicationDate":"2026-08-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13508786/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148471944","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"mSphere Legacy: Fritz about Fritz.","authors":"Friedrich Götz","doi":"10.1128/msphere.00361-26","DOIUrl":"10.1128/msphere.00361-26","url":null,"abstract":"<p><p>Looking back over the past 50 years, staphylococcal research has evolved from a relatively narrow niche into a broad, interdisciplinary field encompassing genetics, genomics, bioinformatics, host-bacterium interactions, immunity, microbial ecology, the microbiota, and commensalism. My career progressed in parallel with these research developments. Much of what contributed to my success was the ability to recognize emerging questions early on, to combine classical microbiology with new technologies as they emerged, and to collaborate with talented students and colleagues across disciplines. Despite the diversity of the topics I have explored, my work has consistently been driven by a central question: what do staphylococci do, and how do they manage to persist so tenaciously? A brief overview of my research interests may illustrate this trajectory.</p>","PeriodicalId":19052,"journal":{"name":"mSphere","volume":" ","pages":"e0036126"},"PeriodicalIF":4.0,"publicationDate":"2026-08-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13508789/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148448360","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Protective immunity against <i>Shigella sonnei</i> in vaccinated and challenged adult Thai volunteers.","authors":"Esther Ndungo, Dilara Islam, Siriphan Gonwong, Nattaya Ruamsap, Patricia L Milletich, Alain Agnememel, Samandra T Demons, Marcela F Pasetti","doi":"10.1128/msphere.00269-26","DOIUrl":"10.1128/msphere.00269-26","url":null,"abstract":"<p><p>A safe, effective, and affordable vaccine that can prevent <i>Shigella</i>-induced diarrhea could have a significant impact on reducing morbidity and mortality in populations at risk. WRSS1, a live attenuated <i>Shigella sonnei</i> vaccine candidate, was well tolerated and immunogenic in adult Thai volunteers, achieving 40% efficacy against wild-type (WT) <i>S. sonnei</i>. We performed an in-depth analysis of mucosal and systemic antibodies in these individuals following WRSS1 vaccination and <i>S. sonnei</i> challenge, including a broader analysis of antibody specificity, functional features, and associations with clinical protection. IgG and IgA against <i>Shigella</i> proteins IpaB, IpaC, IpaD, IpaH, VirG, and LPS from multiple strains, as well as complement-mediated bactericidal and opsonophagocytic killing activity, were assessed in serum, fecal extracts, and antibodies in lymphocyte supernatants. <i>Shigella-</i>specific serum and ALS IgG and IgA increased after WRSS1 vaccination and <i>S. sonnei</i> challenge, particularly in naïve individuals, and most robustly post-challenge. Shedding the vaccine or infecting strain was associated with ALS responses. Fecal IgA was broadly reactive to most antigens, while fecal IgG was specific for <i>S. sonnei</i> LPS. Functional antibodies were detected prominently in fecal extracts; the highest responders were naïve individuals post-challenge. Notably, higher protein-specific serum IgA titers before challenge were associated with clinical protection against disease. Our results highlight the nuanced immunity to <i>Shigella</i> in endemic regions and the importance of understanding the elements that mediate protection in these settings to inform effective vaccine implementation.IMPORTANCEUnderstanding the immune response in <i>Shigella</i>-endemic regions is critical for the design and implementation of vaccines for the target population. We characterized the breadth of systemic and mucosal antibody responses to WRSS1 vaccination and WT <i>S. sonnei</i> challenge in Thai adult volunteers. Antigen-specific IgG and IgA in ALS were elevated only in individuals who shed the vaccine or challenge strain, indicating exposure. Serum IgA responses to <i>Shigella</i> proteins were associated with clinical protection. Our findings underscore the value of serosurveillance in guiding public health interventions and support the concept of protein-based vaccines to prevent disease in high-burden settings.</p>","PeriodicalId":19052,"journal":{"name":"mSphere","volume":" ","pages":"e0026926"},"PeriodicalIF":4.0,"publicationDate":"2026-08-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13508790/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148620769","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Plasmid-mediated antimicrobial resistance across One Health sectors: transmission dynamics and surveillance needs.","authors":"Nuha Fairusya, Rongxuan Wang, Ryo Honda","doi":"10.1128/msphere.00192-26","DOIUrl":"10.1128/msphere.00192-26","url":null,"abstract":"<p><p>Antimicrobial resistance (AMR) is increasingly recognized as a One Health challenge driven by the continuous exchange of resistant bacteria and resistance determinants across human, animal, and environmental sectors. While genomic surveillance has substantially improved detection of antimicrobial resistance genes (ARGs), most monitoring frameworks remain gene- or isolate-centric, limiting insight into the mechanisms that govern resistance transmission and persistence. Recent evidence indicates that plasmids, self-replicating mobile genetic elements (MGEs) capable of horizontal transfer across bacterial species, play an important role in disseminating clinically relevant resistance determinants across sectors. In this mini-review, we synthesize genomic and ecological evidence demonstrating that a limited number of plasmid incompatibility (Inc) groups recur across human, animal, and environmental reservoirs, often independent of bacterial host lineages. We highlight how plasmid transmission dynamics are shaped by host-independent mobility, ecological generalism, co-selection with accessory traits, and persistence in engineered and natural environments. We further examine why current AMR surveillance approaches, including ARG-centric metagenomics and isolate-based monitoring, systematically overlook these plasmid-mediated processes. Furthermore, we propose that plasmid-resolved analysis represents a critical and currently underutilized complementary layer for One Health AMR surveillance. Integrating plasmid classification and genomic reconstruction into wastewater-based epidemiology and cross-sector monitoring frameworks can improve attribution of transmission pathways, enhance early detection of high-risk resistance, and provide a mechanistic foundation for risk-informed intervention strategies.</p>","PeriodicalId":19052,"journal":{"name":"mSphere","volume":" ","pages":"e0019226"},"PeriodicalIF":4.0,"publicationDate":"2026-08-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13508788/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148472014","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Comparative genomic and phenotypic analysis of <i>Corynebacterium macginleyi</i> from ocular infections.","authors":"Qiheng Yuan, Yangyang Shen, Xiaowei Liu, Bianjin Sun, Meiqin Zheng","doi":"10.1128/msphere.00408-26","DOIUrl":"10.1128/msphere.00408-26","url":null,"abstract":"<p><p><i>Corynebacterium macginleyi</i> is an opportunistic pathogen linked to ocular infections, but comprehensive genomic studies remain scarce, especially in China. This study characterized its genomic features, virulence potential, and antimicrobial resistance using 13 clinical isolates and 27 public genomes. Methods included matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS), average nucleotide identity (ANI), whole-genome sequencing, Clusters of Orthologous Groups/Kyoto Encyclopedia of Genes and Genomes annotation, core-single nucleotide polymorphism phylogeny, virulence and resistance gene analysis, and Clinical and Laboratory Standards Institute susceptibility testing. All isolates were accurately identified as <i>C. macginleyi</i>, with MALDI-TOF MS and ANI outperforming conventional methods. Phylogenetic analysis revealed three clades with geographic clustering. Functional profiles were centered on metabolism. Virulence genes were conserved, mainly mediating adhesion, stress response, and immune evasion. Resistance genes were limited but diverse, dominated by <i>erm(X</i>). Phenotypic testing showed frequent macrolide resistance, while most isolates remained susceptible to the other tested antimicrobials; fluoroquinolone resistance was detected in a subset of isolates. Isolate B64 exhibited a unique phylogenetic position, higher virulence, and resistance gene burden, consistent with multidrug resistance. In conclusion, <i>C. macginleyi</i> shows geographic diversity, conserved virulence, and evolving resistance, supporting precise identification and continuous surveillance.IMPORTANCEThe precise molecular mechanisms underlying the pathogenicity of <i>Corynebacterium macginleyi</i> are not fully elucidated, and large-scale genomic and epidemiological studies are still limited, particularly in certain regions such as China. Therefore, comprehensive investigations integrating whole-genome sequencing with clinical data are urgently needed to better understand its genetic characteristics, virulence-associated traits, and antimicrobial resistance profiles. Such efforts will provide a critical foundation for improving diagnostic accuracy and optimizing therapeutic strategies for ocular infections caused by this organism.</p>","PeriodicalId":19052,"journal":{"name":"mSphere","volume":" ","pages":"e0040826"},"PeriodicalIF":4.0,"publicationDate":"2026-08-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13508792/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148670113","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Cyclic di-AMP signaling and regulation in <i>Staphylococcus aureus</i>.","authors":"Seonmin Lee, Ji-Hoon Kim, Taegwan Yun, Wonsik Lee","doi":"10.1128/msphere.00019-26","DOIUrl":"10.1128/msphere.00019-26","url":null,"abstract":"<p><p>Cyclic di-AMP (c-di-AMP) is an essential bacterial second messenger that coordinates multiple cellular processes and is closely linked to central physiology in many bacteria. In <i>Staphylococcus aureus</i>, both depletion and excessive accumulation of c-di-AMP impair bacterial fitness, indicating that this signaling pathway must be tightly regulated. Recent studies have identified c-di-AMP receptor proteins in <i>S. aureus</i>, revealing how c-di-AMP maintains osmotic balance through ion transport and influences cell envelope function and stress adaptation. These regulatory effects also influence bacterial growth and cell size, and are linked to biofilm formation and β-lactam resistance. Elevated c-di-AMP levels can alter peptidoglycan architecture and reduce autolysis, thereby increasing β-lactam resistance, whereas reduced c-di-AMP levels can increase β-lactam susceptibility. This review summarizes current understanding of c-di-AMP synthesis, degradation, and receptor-mediated signaling in <i>S. aureus</i>. We also discuss emerging approaches to perturbing intracellular c-di-AMP balance as potential antimicrobial strategies.</p>","PeriodicalId":19052,"journal":{"name":"mSphere","volume":" ","pages":"e0001926"},"PeriodicalIF":4.0,"publicationDate":"2026-08-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13508791/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148630995","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Dissolved oxygen concentrations influence microbial community structure and key players in an oxygen minimum zone.","authors":"Kaitlin R Dombroski, Lauren G Campbell, Robert M Morris, Olivia U Mason","doi":"10.1128/msphere.00751-25","DOIUrl":"10.1128/msphere.00751-25","url":null,"abstract":"<p><p>Oxygen minimum zones (OMZs) are expanding in the global ocean. Declining oxygen can alter microbial processes that regulate carbon, nitrogen, and sulfur cycling, including pathways with the potential to produce nitrous oxide (N₂O), a potent greenhouse gas. Yet, we lack a full understanding of how microbial communities respond to declining oxygen in some globally important OMZs. This is particularly true for the understudied northern Benguela Upwelling System (nBUS), an important source of marine N₂O. Here, we analyzed the influence of oxygen concentrations on microbial communities in the nBUS OMZ using 16S rRNA gene sequence data. Microbial diversity did not decline linearly with oxygen and was highest under dysoxic (0.2-2.0 mL/L) conditions and lowest under suboxic (0.0-0.2 mL/L) conditions. This pattern was primarily due to changes in community evenness, which decreased in suboxic samples as the relative abundance of <i>Thioglobaceae</i> (SUP05) increased. <i>Thioglobaceae</i> relative abundance was significantly inversely correlated with oxygen, and <i>Thioglobaceae</i> were abundant in the nBUS OMZ. Analysis of 216 publicly available medium- to high-quality <i>Thioglobaceae</i> genomes from cultured and uncultured microbes sampled in the nBUS and other OMZs revealed the metabolic potential of this clade for carbon fixation and consumption, sulfur oxidation, and denitrification. Importantly, few <i>Thioglobaceae</i> possess the genetic potential to carry out complete denitrification as most lack the gene that converts N₂O to dinitrogen gas. As OMZs expand in size and severity, decreasing microbial diversity and a concomitant increase in the relative abundance of <i>Thioglobaceae</i> could contribute to enhanced N₂O production through incomplete denitrification.IMPORTANCEMarine microbes mediate biogeochemical cycles, which are influenced by oxygen concentrations, including microbial pathways that can lead to nitrous oxide (N₂O) production. The oxygen minimum zone (OMZ) in the northern Benguela Upwelling System (nBUS) is a biogeochemical hotspot and an important source of nitrous oxide. Yet, microbial community responses remain poorly characterized in this understudied OMZ. Analysis of microbial communities in this OMZ, combined with comparative genomic analysis of <i>Thioglobaceae</i> from the global ocean, revealed that members of this group have the capacity to fix carbon, potentially supporting growth through sulfur oxidation coupled to denitrification. However, few <i>Thioglobaceae</i> have the genetic potential to carry out complete denitrification, with the final nitrous oxide reduction step often missing. Incomplete denitrification is an important source of N₂O in OMZs. Collectively, this study linked oxygen-associated community shifts in this OMZ to incomplete denitrification in a microbial group that increased in relative abundance as oxygen declined.</p>","PeriodicalId":19052,"journal":{"name":"mSphere","volume":" ","pages":"e0075125"},"PeriodicalIF":4.0,"publicationDate":"2026-08-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13508795/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148448362","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Phenotypic diversity and shared genomic determinants among isolates causing a large incidence of disseminated gonococcal infections in Canada.","authors":"Gursonika Binepal, Emil Jurga, Duncan Carruthers-Lay, Sören Krüger, Sandra Zittermann, Jessica Minion, Mathew Diggle, David C Alexander, Irene Martin, Vanessa Allen, John Parkinson, Scott D Gray-Owen","doi":"10.1128/msphere.00051-26","DOIUrl":"10.1128/msphere.00051-26","url":null,"abstract":"<p><p>The incidence of disseminated gonococcal infection (DGI) has remained low since the advent of antibiotics; however, a recent surge in DGI has inexplicably emerged during the past decade. In an effort to understand whether <i>Neisseria gonorrhoeae</i> that cause disseminated disease can be differentiated from non-invasive strains, we have performed a phenotypic and genotypic analysis on a selection of isolates obtained from invasive and uncomplicated infections in Canada. The increase in DGI was initially associated with a single antibiotic-susceptible gonococcal lineage, but later cases have been caused by diverse strains. Phenotypic analysis of a matched subset of 20 isolates obtained since 2013 found that these varied in their capacity to aggregate in suspension and in their association with serum complement proteins; however, these interactions did not discriminate between the invasive and mucosal isolates. Sequence typing of 360 Canadian isolates revealed that two variant porBa alleles are significantly associated with the DGI strains, one of these being present throughout the past decade, whereas the other emerged more recently. A PopNet-based population dynamics analysis, which instead establishes relationships based upon variance among discrete chromosomal segments, revealed that DGI isolates were restricted to distinct subpopulations within their phylogenetic distribution, implying a genetically linked potential to cause invasive disease. Consistent with this, a large number of genetic determinants are enriched in the DGI strains, making these enticing candidates to explain the increased capacity of <i>N. gonorrhoeae</i> to cause systemic infection and/or reduce the presentation of clinical symptoms from localized infection so that it remains untreated.IMPORTANCEThe re-emergence of disseminated gonococcal infections (DGIs) has raised concern that the virulence of some strains has increased due to their acquisition of a new capacity to remain asymptomatic during uncomplicated mucosal infection and/or to invade the bloodstream and persist upon establishing colonization at distal tissue sites. The molecular epidemiology of a very large incidence of DGI in Canada, which began from a single strain but then diversified with time, provided an opportunity to understand whether the invasive isolates were either phenotypically or genotypically related. While classical phenotypic analysis did not discriminate between mucosal and invasive isolates, a population dynamics-based approach established that the DGI isolates are present within distinct subpopulations of <i>Neisseria gonorrhoeae</i> and reveals genetic determinants that are linked to this phenotype. This suggests that the DGI phenotype emerged multiple times independently and/or the genetic features responsible have been transmitted among the populations.</p>","PeriodicalId":19052,"journal":{"name":"mSphere","volume":" ","pages":"e0005126"},"PeriodicalIF":4.0,"publicationDate":"2026-08-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13508793/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148520648","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}