Microbiology spectrum最新文献

{"title":"Uropathogenic <i>Escherichia coli</i> escapes autolysosome exocytosis by inhibiting autophagosome-lysosome fusion.","authors":"Shenpeng Zhang, Sheng Wang, Jianwei Mu, Yujing Huang, Minghao Tang, Xueping Li, Feng He","doi":"10.1128/spectrum.01154-26","DOIUrl":"https://doi.org/10.1128/spectrum.01154-26","url":null,"abstract":"<p><p>Urinary tract infections (UTIs), predominantly caused by uropathogenic <i>Escherichia coli</i> (UPEC), represent a massive global health burden. UPEC infects bladder epithelial cells (BECs) via fusiform vesicles and then escapes into the cytosol, either establishing biofilm-like intracellular bacterial communities (IBCs), which protect UPEC from host immune clearance, or is captured by autophagy and expelled in a transient receptor potential cation channel 3-dependent manner from lysosomes. The mechanisms enabling UPEC to evade this exocytosis defense to establish IBCs remain poorly defined. Here, we reveal that UPEC nucleoside-diphosphate kinase (NDK) reduces the lysosomal exocytosis of BECs by inhibiting host cell autophagic flux <i>in vitro</i> and <i>ex vivo</i>. Mechanistically, NDK interacts with the small GTPase Rab7, thereby impairing autophagosome-lysosome fusion. Small interfering RNA interferes with Rab7 in 5637 cells and abrogates lysosomal exocytosis for UPEC. Thus, our results reveal a critical role for NDK in inhibiting autophagic flux, thereby favoring bacterial escape from host lysosomal exocytosis in UPEC.</p><p><strong>Importance: </strong>Zhang et al. uncover a novel immune evasion strategy employed by uropathogenic <i>Escherichia coli</i> (UPEC), a leading cause of urinary tract infections. By demonstrating that the bacterial nucleoside-diphosphate kinase (NDK) directly targets the host small GTPase Rab7 to block autophagosome-lysosome fusion, this study reveals how UPEC resists lysosomal exocytosis-a key host defense mechanism that normally expels intracellular pathogens. Importantly, the authors validate that Rab7 interference via small interfering RNA reduces UPEC exocytosis, confirming the mechanistic necessity of this pathway. These insights fundamentally shift the understanding of UPEC pathogenesis from passive survival to active, molecular-level manipulation of host vesicular trafficking. Moreover, by identifying NDK-Rab7 interaction as a critical checkpoint in autophagic flux, this work opens new avenues for host-directed therapies that restore lysosomal exocytosis and enhance bacterial clearance, offering a promising alternative or adjunct to traditional antibiotics that face rising resistance.</p>","PeriodicalId":18670,"journal":{"name":"Microbiology spectrum","volume":" ","pages":"e0115426"},"PeriodicalIF":4.1,"publicationDate":"2026-10-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149195202","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The Qing Chang Hua Shi Formula combined with allicin alleviates <i>Cryptosporidium parvum</i> infection in immunosuppressed mice and is associated with restoration of NLRP6, IL-18, IFN-γ, and intestinal microbiota.","authors":"Chang Xu, Xinyue Wu, Qing He, Luying Yang, Saima Talib, Kun Li","doi":"10.1128/spectrum.03662-25","DOIUrl":"https://doi.org/10.1128/spectrum.03662-25","url":null,"abstract":"<p><p><i>Cryptosporidium parvum</i> is a highly pathogenic zoonotic parasite with limited therapies. Current study explored the anti-<i>C</i>. <i>parvum</i> effect of Qing Chang Hua Shi Formula (QHF) and allicin <i>in vitro</i> in immunosuppressed mice. <i>In vitro</i>, QHF and allicin inhibited over 90% of <i>C. parvum</i>. <i>In vivo</i>, the 8-day treatment reduced fecal oocyst shedding to 12.88% of the model group. Infection disrupted intestinal homeostasis, reduced tight-junction protein expression, and downregulated NLRP6, while inducing systemic inflammation and elevating IL-18/IFN-γ levels, which were further increased by treatment. Treated mice also showed increased abundance of <i>Archangium</i> and <i>Corallococcus</i> and decreased abundance of <i>Clostridioides</i> and <i>Butyricimonas</i>. Predicted microbial functional pathways revealed enrichment of glycolysis-related genes (L-lactate dehydrogenase [LDH], glyceraldehyde-3-phosphate dehydrogenase [GAPDH]) in infected mice, with treatment-associated shifts in amino acid synthesis pathways. Molecular docking suggested potential binding of benzoylpaeoniflorin, baicalin, and wogonoside to <i>C. parvum</i> LDH, ATP/ADP translocase, and gp40/15. Together, these findings indicate that QHF combined with allicin alleviates <i>C. parvum</i> infection in immunosuppressed mice and is associated with restoration of intestinal barrier markers, immune responses, and gut microbiota composition, suggesting a potential therapeutic approach for cryptosporidiosis.IMPORTANCECurrent study demonstrates that Qing Chang Hua Shi Formula (QHF) combined with allicin effectively inhibits <i>Cryptosporidium parvum</i> proliferation and concurrently mitigates intestinal damage and dysbiosis induced by <i>C. parvum</i> infection. QHF treatment was associated with upregulation of NLRP6, improved gut microbiota profiles, and elevated IFN-γ levels. These changes correlated with reduced parasite burden and alleviated intestinal injury, suggesting a potential immunomodulatory role that warrants further mechanistic investigation. Metagenomics disclosed that QHF and allicin were associated with changes in predicted microbial functional pathways, including those involved in glycolysis and amino acid metabolism, and with enrichment of certain bacterial taxa, such as <i>Corallococcus</i> and <i>Archangium</i>. Molecular dynamics simulations suggested that benzoylpaeoniflorin and baicalin may bind stably to <i>C. parvum</i> L-lactate dehydrogenase (LDH) and ATP/ADP translocase, raising the hypothesis that they could interfere with parasite energy metabolism. However, enzymatic validation is required to confirm this possibility. These findings suggest a potential therapeutic approach for cryptosporidiosis and highlight alterations associated with <i>C. parvum</i> infection.</p>","PeriodicalId":18670,"journal":{"name":"Microbiology spectrum","volume":" ","pages":"e0366225"},"PeriodicalIF":4.1,"publicationDate":"2026-10-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149195223","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The effects of novel oral preclinical PolC inhibitor antibiotic candidates on the gut microbiome in a murine thigh infection model.","authors":"Abdulwhab Shremo Msdi, Khurshida Begum, Chenlin Hu, Neil Shaw, Alexander Mai, M Jahangir Alam, Eugénie Bassères, Taryn Eubank, Xiang Y Yu, Lawrence I Mortin, Michael H Silverman, Kevin W Garey","doi":"10.1128/spectrum.01143-26","DOIUrl":"https://doi.org/10.1128/spectrum.01143-26","url":null,"abstract":"<p><p>Antibiotics can negatively affect gut microbiome composition and function. However, preclinical evaluations of antibiotic effects on the microbiome are rarely undertaken. The purpose of this study was to characterize pharmacokinetics and metagenomic profiles of PolC inhibitor compounds compared to linezolid in a neutropenic murine thigh infection model. Neutropenic mice thighs were inoculated with methicillin-resistant <i>Staphylococcus aureus</i> (MRSA) and dosed orally starting 1 h later with ACX-728, ACX-801, ACX-978, or linezolid. Untreated control mice were euthanized at 1 h for baseline data, and a second untreated group were euthanized at 24 h after the start of dosing, when all remaining mice were euthanized. At euthanasia, thigh muscles were excised for MRSA quantification, and fecal pellets, colon tissue, and plasma samples were collected for drug concentration and microbiome analyses. All PolC inhibitors were detectable in plasma and feces at 25 h. Compared with linezolid, PolC inhibitors maintained greater gut microbial richness and diversity in this acute murine infection model. PolC-treated samples preserved overall community structure and <i>Bacteroidota</i> dominance, whereas linezolid induced marked disruption, with secondary expansion of <i>Pseudomonadota</i>, primarily <i>Escherichia coli</i>. Microbial pathway analysis showed preservation of community-level metabolic function for PolC inhibitors but marked disruption by linezolid. Compared to controls, linezolid produced a 4.4 log reduction in MRSA colony-forming unit per gram, while the PolC inhibitors produced a mean log reduction of 0.4-2.5 per group. In these exploratory studies, PolC inhibitor compounds preserved anaerobic community structure and fermentative capacity, whereas linezolid induced depletion of healthy commensals and expansion of aerotolerant taxa. These findings highlight the importance of microbiome-informed antibiotic evaluation in preclinical studies. Larger preclinical and clinical studies are warranted to confirm these findings.</p><p><strong>Importance: </strong>This study evaluated the class effect of PolC inhibitors on the microbiome as part of the preclinical development plan for systemic PolC inhibitors. Similar to the non-absorbable antibiotic, ibezapolstat, a narrow effect on the microbiome was observed with these novel compounds.</p>","PeriodicalId":18670,"journal":{"name":"Microbiology spectrum","volume":" ","pages":"e0114326"},"PeriodicalIF":4.1,"publicationDate":"2026-10-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149195243","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Genome sequencing and broad-spectrum plant growth-promoting effects of the multifunctional PGPR strain <i>Priestia aryabhattai</i> B8.","authors":"Qiyu Zhang, Ning Yu, Hepeng Song, Mingyu Wu, Hui Li, Yumin Cao, Weichang Gao, Qiujuan Jiao, Haitao Liu, Jiayang Xu, Ying Jiang","doi":"10.1128/spectrum.01531-26","DOIUrl":"https://doi.org/10.1128/spectrum.01531-26","url":null,"abstract":"<p><p>A multifunctional plant growth-promoting bacterial strain designated as B8 was isolated from the rhizosphere soil of tobacco under continuous cropping. According to morphological, biochemical, and physiological characteristics, and supported by genomic phylogenetic analysis, the strain was identified as <i>Priestia aryabhattai</i>. Phenotypic assays showed that B8 exhibits multiple plant growth-promoting traits, including indole-3-acetic acid (IAA) production, phosphate and potassium solubilization, and siderophore production. Whole-genome sequencing and functional annotation revealed that the genome of B8 consists of one circular chromosome and two plasmids, harboring a complete tryptophan biosynthesis pathway (<i>trpABCDEF</i>), a phosphate-specific transport system (<i>pstSABC</i>), potassium transporter genes (<i>khtT/khtU</i>), and a siderophore biosynthetic gene cluster. Additionally, genes encoding carbohydrate-active enzymes, such as chitinases and β-glucanases involved in cell wall degradation, along with multiple secondary metabolite biosynthetic gene clusters, were identified, providing a molecular basis for its multifunctional plant growth-promoting and biocontrol potential. Pot experiments indicated that inoculation with strain B8 was associated with significantly increased contents of IAA, available phosphorus, and available potassium in the rhizosphere soils of tobacco, pak choi, and wheat, as well as enhanced plant growth and root development. Field trials further suggested that B8 treatment correlated with significantly improved tobacco plant height, stem circumference, and maximum leaf area, along with elevated contents of total sugar, reducing sugar, and potassium in tobacco leaves. Multivariate statistical analyses pointed to soil available phosphorus, available potassium, and IAA content as key factors driving crop growth. This study provides insights into the multifunctional mechanisms of <i>Priestia aryabhattai</i> B8, offering a theoretical foundation and microbial resource for biofertilizer development.IMPORTANCEThis work advances sustainable agriculture by introducing a multifunctional soil bacterium, <i>Priestia aryabhattai</i> B8, as an eco-friendly alternative to reduce reliance on chemical fertilizers. By demonstrating that this single strain enhances the growth and quality of diverse crops, including tobacco, pak choi, and wheat, in pot experiments and by further validating its growth-promoting effects on tobacco in the field, this research confirms the practical potential of beneficial microbes for improving crop productivity. The comprehensive genomic and functional insights gained into the bacterium's nutrient-solubilizing and hormone-producing mechanisms provide a solid foundation for designing robust and predictable biofertilizers. Overall, this investigation contributes to lowering chemical inputs, restoring soil fertility, and promoting environmentally sustainable food production systems.</p>","PeriodicalId":18670,"journal":{"name":"Microbiology spectrum","volume":" ","pages":"e0153126"},"PeriodicalIF":4.1,"publicationDate":"2026-10-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149195233","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Tracking eco-evolutionary patterns among oropharyngeal pathobiome members in a pediatric cystic fibrosis cohort.","authors":"Lukas Schwyter, Roger Kuratli, Serena Provveduto, Phoebe Do Carmo Silva, Philipp Latzin, Freya Harrison, Markus Hilty, Rolf Kümmerli","doi":"10.1128/spectrum.01577-26","DOIUrl":"https://doi.org/10.1128/spectrum.01577-26","url":null,"abstract":"<p><p>Polymicrobial airway colonization is common in individuals with cystic fibrosis (CF). Pathogen communities typically follow an ecological succession in which early colonizers, such as <i>Haemophilus influenzae</i> and <i>Staphylococcus aureus,</i> are later joined by <i>Pseudomonas aeruginosa</i>. Although adaptation to the lung environment is well described for single pathogens in adult people with CF, much less is known about the role of pathogen interactions and how changes in individual pathogens influence community dynamics at the early stages of disease. To address these questions, we combined genome sequencing with phenotypic screens and pathogen interaction assays using longitudinal clinical isolates (19 <i>P. aeruginosa</i>, 44 <i>S. aureus</i>, and 21 <i>H. influenzae</i>) collected from 23 children with CF (0-7.9 years of age) enrolled in the Swiss Cystic Fibrosis Infant Lung Development (SCILD) cohort. Our analysis suggests that early pathogen communities are characterized by a combination of strain turnover and persistence of specific isolates that go along with cohort-wide, age-associated shifts in pathogen phenotypes and interaction patterns. Most notably, quorum-sensing-deficient <i>P. aeruginosa</i> variants repeatedly emerged, showing reduced protease production and diminished inhibition of <i>S. aureus</i> and <i>H. influenzae</i>. These changes demonstrate that <i>P. aeruginosa</i> isolates from older children exhibit reduced antagonism toward co-occurring pathogens via secreted factors. Together, our results show that ecological and evolutionary dynamics between pathobiome members may play an underappreciated role in shaping CF lung disease during early childhood.</p><p><strong>Importance: </strong>Our study shows how bacterial communities in the lungs of children with cystic fibrosis change during the earliest stages of disease. By tracking three major pathogens over time, we found that both replacement of strains and persistence shape colonization dynamics and pathogen interaction patterns. In particular, <i>Pseudomonas aeruginosa</i> frequently showed mutations that reduced its production of harmful compounds and weakened its ability to inhibit other bacteria. These changes indicate that interspecies interactions are dynamic during early childhood. Understanding these early interaction patterns provides useful cues about potential future microbial management in cystic fibrosis.</p>","PeriodicalId":18670,"journal":{"name":"Microbiology spectrum","volume":" ","pages":"e0157726"},"PeriodicalIF":4.1,"publicationDate":"2026-10-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149195241","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A PhoP-regulated type II secretion system drives bacterial competition in <i>Serratia marcescens</i>.","authors":"María Sol Sartori, Brayan S Arango Gil, Eleonora García Véscovi, Javier F Mariscotti","doi":"10.1128/spectrum.02169-26","DOIUrl":"https://doi.org/10.1128/spectrum.02169-26","url":null,"abstract":"<p><p><i>Serratia marcescens</i> is an enteric bacterium that can act as an opportunistic pathogen, with increasing incidence in clinical settings. This is largely due to its ability to express a broad repertoire of virulence factors and acquire antibiotic resistance mechanisms. Consequently, <i>S. marcescens</i> has been designated by the World Health Organization (WHO) as a research priority for the development of alternative antimicrobial strategies. In this study, we identify a previously unrecognized role of the type II secretion system (T2SS) in mediating bacterial competition in the clinical strain <i>S. marcescens</i> RM66262. Phylogenomic analysis reveals that the T2SS is conserved among clinical isolates but absent from most environmental strains, suggesting it confers a selective advantage in host-associated or highly competitive environments. Functional assays demonstrate that the T2SS contributes to both inter- and intraspecies antagonism and acts in concert with the contact-dependent type VI secretion system (T6SS), with both systems contributing additively to bacterial killing through distinct mechanisms. We further show that T2SS expression is positively regulated by the PhoP/PhoQ two-component system through direct binding to its promoter region and is induced in response to competitive cues such as attack by <i>Acinetobacter nosocomialis</i>. Altogether, our findings expand the functional scope of the T2SS beyond classical extracellular virulence, establishing it as a PhoP-regulated system involved in bacterial competition and a promising target for novel anti-virulence strategies.</p><p><strong>Importance: </strong>This work uncovers a previously uncharacterized role for the type II secretion system (T2SS) in <i>Serratia marcescens</i>, demonstrating its involvement in both inter- and intraspecies bacterial competition. The finding that the T2SS is conserved among clinical isolates but largely absent in environmental strains suggests that this system confers a selective advantage in host-associated or high-competition settings. Furthermore, we show that T2SS expression is regulated by the PhoP/PhoQ system and induced by interbacterial contact, underscoring its role in adaptive antagonistic responses. By expanding the known functional scope of the T2SS, this study provides new insights into the ecological strategies of opportunistic pathogens and highlights a promising target for anti-virulence therapeutic development.</p>","PeriodicalId":18670,"journal":{"name":"Microbiology spectrum","volume":" ","pages":"e0216926"},"PeriodicalIF":4.1,"publicationDate":"2026-10-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149195255","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Prevalence of <i>Neisseria gonorrhoeae</i>, <i>Ureaplasma urealyticum</i>, and <i>Chlamydia trachomatis</i> infections in 37,680 patients in Guangzhou, China.","authors":"Jiaying Li, Meiling Liu, Guoyi Weng, Wuwei Zeng, Bangming Xu, Donglin Cao","doi":"10.1128/spectrum.00156-26","DOIUrl":"https://doi.org/10.1128/spectrum.00156-26","url":null,"abstract":"<p><p>To refine the epidemiological profile of sexually transmitted infections (STIs) in Guangzhou, this study analyzed <i>Neisseria gonorrhoeae</i> (NG), <i>Ureaplasma urealyticum</i> (UU), and <i>Chlamydia trachomatis</i> (CT) infections among 37,680 patients treated at the Affiliated Guangdong Second Provincial General Hospital of Jinan University from 2020 to 2024. Overall prevalence was 15.48% for NG, 30.91% for UU, and 4.78% for CT. NG and CT prevalences were both significantly higher in males than in females (NG: 25.07% vs 2.86%; CT: 5.33% vs 4.28%), whereas UU prevalence was higher in females (41.67% vs 24.96%). Age-specific patterns revealed distinct trends. NG prevalence in males peaked in the ≤20 age group (48.34%) and declined with age. UU prevalence was highest in females ≤20 years (60.00%). CT prevalence peaked in youth ≤20 years (25% and 30.34% for males and females, respectively), with lower rates observed in subsequent age groups. Regarding co-infections, UU+CT was the most frequent (5.00%). NG+UU and NG+CT co-infections were male-predominant, whereas UU+CT was significantly higher in females ≤20 years (36.00% vs 13.95%). <i>O</i>/<i>E</i> and OR analyses suggested a synergistic interaction for UU+CT in both sexes aged ≤30 years. Triple infection (NG+UU+CT) remained below 1% and showed no significant sex difference. Stratified by clinical presentation, NG and CT infections in males were highly concentrated in the urogenital inflammation group, demonstrating a symptom-driven pattern. In females, CT infection was prevalent in the urogenital inflammation (7.37%), others (7.11%), and screening and asymptomatic examination (5.86%) groups, and NG was detected in both the inflammation (3.46%) and screening (3.61%) groups, indicating a coexistence of symptomatic and occult infections. UU showed consistently high prevalence across all female clinical groups (32.50%-46.07%). Our study provided evidence for tailored STI control strategies.</p><p><strong>Importance: </strong>This study systematically characterized the epidemiological profile of <i>Neisseria gonorrhoeae</i> (NG), <i>Ureaplasma urealyticum</i> (UU), and <i>Chlamydia trachomatis</i> (CT) infections in Guangzhou, revealing distinct sex- and age-specific patterns, identifying UU+CT as the predominant co-infection with a synergistic interaction in individuals aged ≤30 years, and demonstrating a symptom-driven pattern for NG and CT in males versus a dual burden of symptomatic and occult infections in females. These findings fill a gap in the epidemiological data in South China and support gender-specific screening strategies that distinguish symptomatic management in males from proactive case-finding in females.</p>","PeriodicalId":18670,"journal":{"name":"Microbiology spectrum","volume":" ","pages":"e0015626"},"PeriodicalIF":4.1,"publicationDate":"2026-10-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149195279","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Artificial genetic augmentation of T6SS activity affects effector repertoire and host toxicity.","authors":"Hadar Cohen, Eyal Elias, Dan Bar Yaacov, Dor Salomon, Motti Gerlic","doi":"10.1128/spectrum.01278-26","DOIUrl":"https://doi.org/10.1128/spectrum.01278-26","url":null,"abstract":"<p><p>Type VI secretion system (T6SS), a toxic effector-delivery apparatus primarily studied for its antibacterial properties, has recently emerged as a widespread anti-eukaryotic determinant, particularly in members of the genus <i>Vibrio</i>. Although various anti-eukaryotic effectors have been described, it remains unknown whether effectors target distinct hosts in a similar manner. Moreover, it is unclear whether the entire effector arsenal encoded in a single genome is co-regulated across different conditions and by the same regulators. Here, we employ the anti-eukaryotic T6SS3 of <i>Vibrio proteolyticus</i> to address these knowledge gaps. By monitoring toxicity during infection of oyster hemocytes and comparing the results with previous infections of murine macrophages, we find that the effector Tie1 plays a role only in intoxicating murine cells, whereas Tie2 intoxicates both cell models. Furthermore, we show that artificial augmentation of T6SS3 activity by deleting the negative regulator <i>hns1</i> fails to induce the orphan effector Tie3, whereas overexpression of the T6SS3-specific activator, Ats3, induces all three known effectors. Using Ats3 overexpression to activate all three effectors, we show that both Tie2 and Tie3 participate in hemocyte intoxication. Collectively, these findings indicate that analyses of T6SS-mediated infections must factor in the possibility of partial activation of the effector repertoire even when the main gene cluster is fully induced, and that the contribution of anti-eukaryotic T6SS effectors to intoxication may be host-dependent.IMPORTANCEThe type VI secretion system (T6SS), a bacterial toxin-delivery apparatus, has recently been shown to mediate virulence in various marine <i>Vibrio</i> species. Each T6SS delivers a cocktail of toxins into a host cell, yet it is unknown whether toxins intoxicate different hosts in the same manner. Moreover, many investigations of T6SSs artificially activate the system by manipulating a transcription factor, yet it remains unknown whether different regulators induce the same toxin repertoire. Here, we show that a T6SS toxin that intoxicates one organism can be inert during the infection of another host. Furthermore, we demonstrate that T6SS-inducing regulators can activate distinct toxin repertoires. These findings suggest that conclusions about the role of T6SS toxins during infection should be drawn with caution, given the specific host model used, especially when the T6SS is artificially activated.</p>","PeriodicalId":18670,"journal":{"name":"Microbiology spectrum","volume":" ","pages":"e0127826"},"PeriodicalIF":4.1,"publicationDate":"2026-10-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149195253","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Requirements for swarming ability by lateral flagella on an agar surface in marine <i>Vibrio</i> cells.","authors":"Michio Homma, Takehiko Mima, Hajime Nakatani, Seiji Kojima","doi":"10.1128/spectrum.02992-26","DOIUrl":"https://doi.org/10.1128/spectrum.02992-26","url":null,"abstract":"<p><p>The marine bacterium <i>Vibrio alginolyticus</i> possesses two types of flagella in one cell: proton-driven lateral flagella extending from the periphery of the cell body and sodium ion-driven polar flagella extending from a cell pole. It is believed that, for swimming in seawater, they use polar flagella, suppressing the expression of lateral flagella, and when they attach to the body surface of a fish or the intestinal tract, lateral flagella are induced, allowing them to crawl along the surface or through mucus. The dynamometer hypothesis, which proposes that polar flagella sense rotation and control the expression of lateral flagellar genes, has been presented. However, how rotation is sensed and how expression is controlled remain unclear. Although swarming has recently been analyzed by physical, biological, or biochemical perspectives, it remains unclear how this motility is controlled, or which substances and conditions are necessary for swarming ability. In this study, we discovered that adding gelatin to agar medium promotes swarming on the agar surface by the lateral flagella of <i>Vibrio</i>. Based on our data, we speculate that surfactants or viscous polysaccharides secreted extracellularly are important for promoting swarming on the agar surface, and we identified that swarming is likely to be driven by S (social)-motility, in which bacteria move by interacting with each other, and A (adventure)-motility, in which bacteria move by interacting with the agar surface. Our study provides clues that help clarify the mechanism of bacterial swarming.IMPORTANCEWe discovered that adding gelatin to hard agar medium promoted swarming on agar surfaces by the lateral flagella of <i>Vibrio</i> cells. The surfactants or viscous polysaccharides secreted extracellularly seem to be important for swarming ability on agar surfaces. We proposed that the swarming is thought to occur through S (social)-motility, where cells move by interacting with cell bodies each other, and A (adventure)-motility, where cells move by interacting with the agar surface and cell body. The present study should provide clues to clarify the mechanism of bacterial swarming and how to move in a viscous environment.</p>","PeriodicalId":18670,"journal":{"name":"Microbiology spectrum","volume":" ","pages":"e0299226"},"PeriodicalIF":4.1,"publicationDate":"2026-10-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149195265","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Electron transport chain: a crucial target of luteolin in combating <i>Trueperella pyogenes</i>.","authors":"Yuru Guo, Yueting Guo, Ruxia Wang, Simiao Wang, Hanyu Zhao, Yingyu Wang, Shengli Niu, Chunlian Tian, Mingchun Liu","doi":"10.1128/spectrum.01985-26","DOIUrl":"https://doi.org/10.1128/spectrum.01985-26","url":null,"abstract":"<p><p><i>Trueperella pyogenes</i> is an opportunistic pathogen capable of causing infections in both domestic and wild animals. Furthermore, the dissemination of resistance genes has resulted in varying degrees of antimicrobial resistance among <i>T. pyogenes</i> isolates. Therefore, it is necessary to develop new anti-<i>T</i>. <i>pyogenes</i> drugs to address its increasing resistance. Luteolin, a natural flavonoid, has been found to exhibit good antibacterial activity against <i>T. pyogenes</i> in our previous research. This study aims to utilize high-throughput proteomics technology to identify potential novel targets and illuminate the action mechanism of luteolin. Our results indicated that luteolin could target electron transport chain complexes I, II, and V to inhibit the oxidative phosphorylation of <i>T. pyogenes</i>. Besides, luteolin could inhibit the enzyme activities involved in glycolysis and the tricarboxylic acid cycle, which eventually leads to a decrease in reduced hydrogen supplied to the electron transport chain and reduces the content of intracellular adenosine triphosphate. Based on the high-throughput proteomic analysis and multiple experimental results, the inhibition of electron transport chain complexes appears to be a significant mechanism by which luteolin exerts its antibacterial effect against <i>T. pyogenes</i>. Overall, this study provides a new insight into the anti-<i>T</i>. <i>pyogenes</i> mechanism of luteolin and offers new targets to develop anti-<i>T</i>. <i>pyogenes</i> drugs.</p><p><strong>Importance: </strong><i>Trueperella pyogenes</i> is an opportunistic pathogen that can cause suppurative infections in multiple animals. Its existing resistance may bring challenges to anti-infection therapy. As a promising natural antibacterial agent, luteolin shows potent activity against this bacterium. This study revealed that luteolin disrupts bacterial energy metabolism by targeting electron transport chain complexes, thereby reducing intracellular adenosine triphosphate content. Our findings expanded the new antibacterial mechanism of luteolin and identified novel targets. This work provides valuable references for developing novel drugs against drug-resistant bacterial infections by targeting the electron transport chain.</p>","PeriodicalId":18670,"journal":{"name":"Microbiology spectrum","volume":" ","pages":"e0198526"},"PeriodicalIF":4.1,"publicationDate":"2026-10-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149195272","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}