International Microbiology最新文献

{"title":"In Vitro antibacterial, anti-biofilm, and virulence-modulating activity of Cinnamomum verum-mediated iron oxide nanoparticles against carbapenem-resistant uropathogenic Escherichia coli.","authors":"Ahmed Abass Fadel, Khalid H Alobaidi, Jameel R Al-Obaidi","doi":"10.1007/s10123-026-00876-3","DOIUrl":"https://doi.org/10.1007/s10123-026-00876-3","url":null,"abstract":"<p><strong>Background: </strong>Carbapenem-resistant Enterobacteriaceae (CRE) represent a critical antimicrobial resistance threat globally, with uropathogenic Escherichia coli (UPEC) CRE isolates increasingly documented in both community and healthcare settings across the Middle East and worldwide. Conventional antibiotic options for CRE UPEC infections are severely constrained, with susceptibility typically retained only to aminoglycosides and fosfomycin, necessitating urgent development of alternative therapeutic strategies.</p><p><strong>Methods: </strong>Iron oxide nanoparticles (Fe₂O₃-NPs) were synthesised using aqueous bark extract of Cinnamomum verum, rich in trans-cinnamaldehyde and eugenol. The synthesised Fe₂O₃-NPs were characterised by UV-Visible spectroscopy, Fourier-transform infrared spectroscopy (FTIR), field-emission scanning electron microscopy (FE-SEM), energy-dispersive X-ray spectroscopy (EDX), atomic force microscopy (AFM), and X-ray powder diffraction (XRD). Antibacterial and anti-biofilm activities were evaluated against two CRE UPEC clinical isolates confirmed by VITEK 2 (carbapenem MIC values: ertapenem ≥ 8 mg/L, imipenem ≥ 16 mg/L, meropenem 8 mg/L). Virulence gene expression was quantified by RT-qPCR using the 2⁻ᴰᴰᶜᵗ method, targeting csgD and fimH with 16 S rRNA as the reference gene.</p><p><strong>Results: </strong>The C. verum extract displayed a UV absorption maximum at 300 nm, which shifted to 290 nm in the Fe₂O₃-NP preparation, consistent with nanoparticle formation. FTIR confirmed Fe-O stretching at 621.08 cm⁻¹ with retained phytochemical surface-capping bands. FE-SEM revealed a mean particle diameter of 65.63 nm; AFM confirmed a mean of 49.23 nm (n = 905 particles). Elemental analysis confirmed the formation of iron oxide nanoparticles with phytochemical capping, while XRD indicated a predominantly amorphous phase consistent with room-temperature biogenic synthesis. The nanoparticle preparation exhibited an MIC of 0.19 mg/mL against the tested CRE UPEC culture, compared with 25 mg/mL for the crude extract. Anti-biofilm activity reached 93.4% (blank-corrected). RT-qPCR indicated reduced csgD and fimH expression in the two evaluable treated samples; these preliminary findings require confirmation using additional biological replicates.</p><p><strong>Conclusion: </strong>These proof-of-concept findings indicate that C. verum-mediated Fe₂O₃-NPs show potent in vitro multi-mechanism antibacterial activity against two clinically confirmed CRE UPEC isolates, combining promising antibacterial potency with transcriptional suppression of key virulence determinants; validation in a larger isolate panel is required to confirm generalisability. These findings identify the nanoparticle preparation as a promising in vitro candidate for further antibacterial and anti-virulence investigation. However, cytotoxicity, biocompatibility, validation using a larger collection of clinical isolates, and in vivo studies are required befor","PeriodicalId":14318,"journal":{"name":"International Microbiology","volume":" ","pages":""},"PeriodicalIF":2.9,"publicationDate":"2026-09-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149016491","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Isolation of a lipase-producing strain from yuncheng salt lake and enhancement of lipase activity via UV mutagenesis.","authors":"Kai Chen, Fan Zhou, Chuanxu Wang, Xin Guo, Huiying Yu, Zhuo Wang, Yunjie Li, Hongjuan Yuan, Jing Yang","doi":"10.1007/s10123-026-00900-6","DOIUrl":"https://doi.org/10.1007/s10123-026-00900-6","url":null,"abstract":"<p><p>Enhancing lipase activity and tolerance can help address energy and environmental challenges. Expanding lipase sources, increasing their activity, and improving their tolerance under various conditions are urgently needed. A water sample collected from Yuncheng Salt Lake was plated using the \"double-layer plate\" method to isolate \"hard-to-culture\" microbes, and a selective medium was used to screen the isolated strain L5, which showed lipase activity. Gram staining and morphological observation, combined with 16 S rRNA gene sequencing and phylogenetic analysis, were used to preliminarily identify this isolate. Culture conditions and enzymatic reaction parameters before and after UV mutagenesis were optimized, and the lipase activities of the parent and mutant strains were compared. The results showed that strain L5, isolated from Yuncheng Salt Lake, possessed lipase activity, was Gram-positive, and was preliminarily identified as a Bacillus seohaeanensis-like strain. The optimum NaCl concentration for the growth of L5 was 15.0%, the optimum pH was 8.0, and the highest cell density was reached at 48 h. For the crude lipase of L5, the optimum NaCl concentration was 25.0%, the optimum reaction temperature was 35.0 °C, and the highest activity was observed at pH 8.0. Trichloromethane had only a minor effect on enzyme activity. After UV mutagenesis and screening, mutant strain L5M exhibited significantly enhanced lipase activity, with maximum activity achieved at 25.0% NaCl, 35.0 °C, and pH 8.0. The mutated enzyme not only tolerated trichloromethane but also retained appreciable activity after tris-aminomethane treatment. Under the optimized conditions, the lipase activity of the mutated strain L5M reached 161.4 ± 5.4 U/mL, 2.96-fold higher than that before UV mutagenesis (54.6 ± 4.7 U/mL). UV mutagenesis improved L5 lipase activity and tolerance, showing better application prospects in environments with drastically fluctuating conditions.</p>","PeriodicalId":14318,"journal":{"name":"International Microbiology","volume":" ","pages":""},"PeriodicalIF":2.9,"publicationDate":"2026-09-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149001884","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Streptomyces rhizobacteria enhance growth and drought tolerance in maize (Zea mays L.) under greenhouse conditions.","authors":"Luísa Machado Ramos, Felipe Dias Bandeira Berleze, Luca Doval Terra de Souza E Souza, Mariana Vieira Franções, Leandro Vieira Astarita, Eliane Romanato Santarém","doi":"10.1007/s10123-026-00896-z","DOIUrl":"https://doi.org/10.1007/s10123-026-00896-z","url":null,"abstract":"<p><p>Drought is among the most severe limitations to crop productivity, impairing plant development. Although plant growth-promoting rhizobacteria have been reported to alleviate drought stress in several crops, little is known about how Streptomyces affect vegetative growth of maize under water deficit. This study investigated rhizospheric Streptomyces isolates as sustainable tools to mitigate drought-related constraints in maize. Isolates CLV16, CLV100, CLV115, and CLV179 were screened under PEG6000-induced water stress (-0.6, -1.0, and - 1.7 MPa, representing mild, moderate, and severe water deficit, respectively) to characterize their growth and plant growth-promoting traits under stress. All isolates remained metabolically active at water potentials down to -1.0 MPa, while phosphate solubilization and siderophore production were maintained across the tested. Under severe water stress, all isolates retained their PGPR- attributes, although showing distinct functional responses: CLV100 showed threefold greater colony growth than the other isolates, whereas CLV115 exhibited the highest production of indolic compounds, with levels 8.9-fold higher than those of the other isolates. CLV179 produced threefold more ammonia than the other isolates, while CLV16 showed the lowest expression of the tested traits. Under greenhouse conditions, Streptomyces-colonized maize plants grown at 30% field capacity (soil moisture 5.4 to12.8%) showed increased root elongation and biomass accumulation compared with well-watered control at 100% field capacity (soil moisture 19.2 to 28.2%). Specifically, CLV100, CLV115 enhanced maize biomass and shoot growth under drought stress. CLV179, besides these improvements on maize growth, resulted in increased root length (22%) in stressed plants compared with non-bacterized control. These findings suggest the potential of Streptomyces isolates as bioinoculants for improving maize performance under water deficit.</p>","PeriodicalId":14318,"journal":{"name":"International Microbiology","volume":" ","pages":""},"PeriodicalIF":2.9,"publicationDate":"2026-09-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148982283","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Gdt1, Gdt2 and the P-type ATPase Pmr1 regulate divalent cations (Ca²⁺ and Mn²⁺) in the fission yeast Schizosaccharomyces pombe.","authors":"Farman Ullah, Ying Huang","doi":"10.1007/s10123-026-00887-0","DOIUrl":"https://doi.org/10.1007/s10123-026-00887-0","url":null,"abstract":"<p><p>In eukaryotes, calcium (Ca²⁺) and manganese (Mn²⁺) ion homeostasis in the early secretory pathway is crucial for protein glycosylation, cell wall biosynthesis, and cell structure. To clarify the roles of the UPF0016 family proteins Gdt1 and Gdt2 in the regulation of divalent cations, we performed genetic and phenotypic analyses on single-gene deletion mutants (Δgdt1, Δgdt2 and Δpmr1) and double-gene deletion mutants in Schizosaccharomyces pombe. In the presence of CaCl₂ and MnCl₂, Δgdt1 cells exhibit marked hypersensitivity, indicating that Gdt1 is a major contributor to divalent cation regulation; in contrast, Δgdt2 and Δpmr1 mutants show only mild growth defects. However, the combined deletion of gdt1 or gdt2 with pmr1 results in a strong synthetic growth phenotype, suggesting that Gdt1, Gdt2, and Pmr1 play complementary roles in maintaining divalent cation regulation within the secretory network. Structural comparative analysis reveals that Gdt1 retains a conserved five-transmembrane structure, whereas Gdt2 adopts a six-transmembrane conformation. Both proteins preserve the EIGDKT and EWGDRS motifs characteristic of UPF0016 transporters. These findings establish Gdt1 as a key determinant of Ca²⁺ and Mn²⁺ regulation and support a complementary role for Gdt2 in ion regulation, a process essential for efficient glycosylation and normal cell wall morphogenesis.</p>","PeriodicalId":14318,"journal":{"name":"International Microbiology","volume":" ","pages":""},"PeriodicalIF":2.9,"publicationDate":"2026-09-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148976731","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Comparative genomics reveals genotype-phenotype concordance and cryptic resistomes in clinical Pseudomonas aeruginosa.","authors":"Sweta Padma Routray, Tripti Swarnkar, Enketeswara Subudhi, Rajashree Panigrahy","doi":"10.1007/s10123-026-00892-3","DOIUrl":"https://doi.org/10.1007/s10123-026-00892-3","url":null,"abstract":"<p><strong>Background: </strong>Pseudomonas aeruginosa (P. aeruginosa) is a major pathogen because of its adaptability. It shows rapid evolution of multidrug resistance (MDR). Phenotype-based diagnostics often fail to detect silent resistance determinants and early adaptive changes. This study integrates phenotypic profiling with whole-genome sequencing (WGS) to examine resistance architecture in clinical isolates from eastern India.</p><p><strong>Methods: </strong>From 1295 culture-positive P. aeruginosa specimens collected at a tertiary care hospital in eastern India. Using predefined criteria, representative MDR and non-MDR isolates were selected, including distinct resistance phenotypes, specimen-source diversity, and hospital and community-acquired settings; multivariate analysis of resistance profiles illustrated phenotypic diversity. Antimicrobial susceptibility assessed using VITEK-2 and Kirby-Bauer disk diffusion, species identity confirmed by 16 S rRNA sequencing, and genomic analysis processed through a reference-guided workflow. Antimicrobial Resistance (AMR) determinants were identified through CARD, and phylogenetic tree constructed from 454 publicly available P. aeruginosa genomes.</p><p><strong>Results: </strong>MDR exhibited greater sequence divergence relative to PA14 (~ 69,000 variants) than the non-MDR isolate (~ 58,700 variants), with > 92% coverage at ≥ 30X depth. Strong genotype-phenotype concordance observed in MDR isolates across five antibiotic classes, associated with β-lactamase variants (PDC-67, OXA-396) and regulatory adaptations (ArmR, cprS). The non-MDR isolate harboured gyrA (T83I) resistance-associated mutations, PDC-1, and OXA-847 without phenotypic expression, indicating silent resistome. Phylogenetically, MDR isolates clustered tightly within the phylogeny, while the non-MDR isolate formed a distinct lineage.</p><p><strong>Conclusion: </strong>Observed genomic differences align with adaptation under antimicrobial selection, though confirmation requires larger collections. The non-MDR isolate retained a silent resistome. Findings highlight limitations of phenotype-only diagnostics, support genomic data integration, and emphasize transcriptomics for hidden resistance expression and regulatory dynamics.</p>","PeriodicalId":14318,"journal":{"name":"International Microbiology","volume":" ","pages":""},"PeriodicalIF":2.9,"publicationDate":"2026-09-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148955869","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Gut microbiota and ABC transporter pathway: potential links to the therapeutic efficacy of Shen-Ling-Bai-Zhu-San against antibiotic-associated diarrhea in juvenile rats.","authors":"Rong Yan, Yun Zeng, Jinfeng Bai, Moyue Li, Yujie Li, Hai Zheng, Jiayi Li, Zhiqing Tan, Min Feng","doi":"10.1007/s10123-026-00891-4","DOIUrl":"https://doi.org/10.1007/s10123-026-00891-4","url":null,"abstract":"<p><strong>Background: </strong>Shen-Ling-Bai-Zhu-San (SLBZS) recorded in the Song Dynasty text \"Tai Ping Hui Min He Ji Ju Fang,\" is traditionally used to \"strengthen the spleen, eliminate dampness and stop diarrhea.\" making it a commonly used prescription for treating antibiotic-associated diarrhea (AAD). This study examined microbial and metabolite changes accompanying SLBZS treatment for AAD and analyzed their potential biological correlates.</p><p><strong>Methods: </strong>Juvenile rats were randomly assigned to control, model, and SLBZS groups. An antibiotic cocktail was administered orally to induce AAD, followed by SLBZS decoction treatment. Body weight and fecal characteristics were monitored. Gut microbiota and fecal metabolites were analyzed using 16 S rDNA sequencing and widely targeted metabolomics, respectively, with correlation analysis performed on the data.</p><p><strong>Results: </strong>SLBZS significantly reduced diarrhea incidence and fecal consistency scores in AAD rats. Antibiotic gavage induced gut microbiota dysbiosis and metabolic disturbances. The abundances of Muribaculaceae, Tannerellaceae, Parabacteroides, and Parabacteroides distasonis were favorably modulated by SLBZS. Twenty-nine common differential fecal metabolites exhibited favorable regulation, with 11 metabolites enriched in the ABC transporter pathway. Correlation analysis revealed that seven metabolites significantly correlated with Parabacteroides distasonis, five of which culstered in the ABC transporter pathway.</p><p><strong>Conclusions: </strong>SLBZS treatment for AAD was associated with altered Parabacteroides distasonis abundance and ABC transporter pathway changes. These factors likely represent key biological targets of SLBZS therapy.</p>","PeriodicalId":14318,"journal":{"name":"International Microbiology","volume":" ","pages":""},"PeriodicalIF":2.9,"publicationDate":"2026-09-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148911983","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Glucosamine functionalized multi-walled carbon nanotubes as potential antibacterial molecules.","authors":"Noor Akbar, Jasra Gul, Ruqaiyyah Siddiqui, Saira Yasmeen, Asia Naz Awan, Tooba Jabri, Muhammad Raza Shah, Naveed Ahmed Khan","doi":"10.1007/s10123-026-00889-y","DOIUrl":"https://doi.org/10.1007/s10123-026-00889-y","url":null,"abstract":"<p><p>Antibiotic resistance represents a critical global health challenge driven by the widespread misuse of antimicrobials and the rapid evolution of multidrug-resistant pathogens. Conventional antibiotics are increasingly limited by poor stability, low bioavailability, toxicity, and reduced efficacy. This study investigates the potential of carbon nanotube-based nanocarriers to enhance antibiotic delivery and efficacy against resistant bacteria. Multi-walled carbon nanotubes were oxidized and functionalized with glucosamine, followed by loading with two antibiotics, ethacridine lactate and sulfamethoxazole, to form nanoconjugates. Characterization studies confirmed successful functionalization and drug loading. Thermogravimetric analysis indicated distinct weight losses corresponding to surface modifications, while Fourier transform infrared spectra verified amide bond formation and drug-nanocarrier interactions. Scanning electron microscopy revealed increased surface roughness and structural defects after functionalization. UV-Vis spectroscopy demonstrated high encapsulation efficiencies (85.37% for ethacridine lactate and 93.69% for sulfamethoxazole). Dynamic light scattering demonstrated hydrodynamic diameters ranging from 127 to 429 nm, moderate polydispersity, and stable negative zeta potentials (-17 to -23 mV), confirming colloidal stability. Biological evaluation against Gram-negative and Gram-positive bacteria demonstrated that drug-loaded nanoconjugates exhibited significantly enhanced antibacterial activity compared to free drugs and individual nanomaterials. The nanoconjugate EL-GA-OMC achieved complete (100%) bacterial inhibition across all tested bacterial strains, while SMX-GA-OMC showed significantly enhanced antibacterial activity compared to the drugs alone. Half-maximal inhibitory concentration (IC₅₀) analysis further confirmed increased potency, with EL-GA-OMC exhibiting the lowest IC₅₀ value (10.20 ± 0.19 µg/mL) against E. coli K1, and 10.74 ± 0.05 µg/mL against S. pneumoniae, indicating superior efficacy at reduced doses. Cytotoxicity analysis using human endothelial cells (HBEC-5i) revealed that nanoconjugates exhibited low cytotoxicity, in contrast to the significant toxicity observed with drug alone. Overall, these findings demonstrate that glucosamine-functionalized carbon nanotubes represent an effective drug delivery system that enhances antibacterial activity while exhibiting low cytotoxicity. These findings support the potential application of glucosamine-functionalized carbon nanotubes as antibiotic delivery platforms for the treatment of multidrug-resistant bacterial infections.</p>","PeriodicalId":14318,"journal":{"name":"International Microbiology","volume":" ","pages":""},"PeriodicalIF":2.9,"publicationDate":"2026-09-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148900436","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Cultivable diversity and plant growth-promoting traits of free-living bacteria from coffee soils under contrasting fertilization systems.","authors":"Cleidiana Vieira Guimarães, Tomás Gomes Reis Velozo, José Maria Rodrigues da Luz, Gabriel Costa Públio, João Paulo Toledo da Silva, Lucas Louzada Pereira, Marliane de Cássia Soares da Silva","doi":"10.1007/s10123-026-00893-2","DOIUrl":"https://doi.org/10.1007/s10123-026-00893-2","url":null,"abstract":"<p><p>Brazilian coffee production relies heavily on mineral fertilizers, particularly nitrogen-based inputs. However, the intensive use of these fertilizers is associated with nutrient losses, elevated production costs, and environmental impacts, highlighting the need for more sustainable alternatives. In this context, plant growth-promoting bacteria (PGPB) represent promising resources for improving nutrient use efficiency and reducing dependence on synthetic inputs. Nevertheless, the cultivable bacterial fraction associated with coffee soils remains poorly characterized under contrasting fertilization management systems. The objectives of this study were to isolate, identify, and characterize cultivable bacterial isolates recovered from Coffea arabica soils managed under conventional mineral fertilization (CMF) and organic fertilization, and to screen them for plant growth-promoting traits. Thirty-eight bacterial isolates were recovered and identified by Sanger sequencing of the 16S rRNA gene. Both fertilization systems shared dominant bacterial groups, although each management harbored exclusive bacterial genera. Eleven bacterial isolates from organic fertilization and nine from CMF exhibited growth in nitrogen-free semi-solid NFb medium. All isolates recovered from organic fertilization and several isolates from CMF solubilized tricalcium phosphate. Furthermore, no significant differences in indole-acetic acid production were observed among the bacterial isolates recovered from both fertilization systems. Overall, the cultivable bacterial fraction associated with both management systems exhibited considerable functional diversity and included multifunctional isolates with plant growth-promoting traits. These findings expand current knowledge of cultivable bacterial diversity in coffee soils and highlight the native microbiota as a promising source of candidate microorganisms for future microbial inoculants and microbial consortia adapted to sustainable coffee production.</p>","PeriodicalId":14318,"journal":{"name":"International Microbiology","volume":" ","pages":""},"PeriodicalIF":2.9,"publicationDate":"2026-09-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148897362","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"In Saccharomyces cerevisiae ΔRIB1 and ΔRIB4 mutants, riboflavin auxotrophy is reverted by Wolbachia (wStr) infection.","authors":"Ofelia Mendez-Romero, Carolina Ricardez-García, Salvador Uribe-Carvajal","doi":"10.1007/s10123-026-00884-3","DOIUrl":"https://doi.org/10.1007/s10123-026-00884-3","url":null,"abstract":"<p><p>In endosymbiosis, unicellular organisms, mostly prokaryotes, live inside the cells of a host that may be uni- or multicellular. More than half insect and arthropod species host the obligate endosymbiont Wolbachia spp., an alpha-proteobacterium that, given time, may coevolve with its host and progress from parasitism to strict mutualism, where an obligate endosymbiont avoids rejection by providing advantages to the host such as essential nutrients. It was recently found that in the wild yeasts may host both facultative and obligate endosymbionts. To model host-symbiont mutualist interactions in yeast, we tested two different Saccharomyces cerevisiae riboflavin-synthesis pathway deletion mutants (ΔRIB1 and ΔRIB4), finding that these failed to grow in the absence of exogenous riboflavin (RF), i.e., they were RF-auxotrophic strains. In both mutants Wolbachia infection cured auxotrophy. In addition, Wolbachia infection led to a mild increase in survival to exposure to 1 M NaCl or to 10 mM hydrogen peroxide. The artificial yeast/endosymbiont model proposed here may become a useful tool to explore parasitic, facultative and mutualist associations.</p>","PeriodicalId":14318,"journal":{"name":"International Microbiology","volume":" ","pages":""},"PeriodicalIF":2.9,"publicationDate":"2026-09-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148891613","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A fitness advantage from the pLVPK plasmid fuels the global spread of a carbapenem-resistant hypervirulent Klebsiella pneumoniae high-risk clone: ST11-KL64.","authors":"Yalu Ren, Xiaoping Li, Li Ju, Yanping Yao, Xu Chen, Xi Wang","doi":"10.1007/s10123-026-00888-z","DOIUrl":"https://doi.org/10.1007/s10123-026-00888-z","url":null,"abstract":"<p><strong>Background: </strong>The global emergence of carbapenem-resistant hypervirulent Klebsiella pneumoniae (CR-hvKP), particularly the ST11-KL64 subclone acquiring pLVPK-like virulence plasmids, represents a critical public health threat. This study investigates the epidemiological dominance and molecular mechanisms underlying ST11-KL64's fitness advantage over KL47 variants.</p><p><strong>Methods: </strong>We performed comparative genomic analysis on 43,722 K. pneumoniae genomes (2011-2022) from 112 countries, focusing on ST11-CRKP strains. Capsular typing (KL64 vs. KL47), virulence gene profiling (aerobactin, RmpADC), and plasmid stability analysis were conducted using Kleborate, RAST, and PlasmidFinder. Plasmid-chromosome interactions were characterized through hybrid assembly approaches.</p><p><strong>Results: </strong>ST11-KL64 demonstrated rapid expansion post-2016, surpassing KL47 as China's dominant CRKP subtype (40.5% vs. 28.9%), with regional predominance in Zhejiang (62.3%) and Sichuan (58.7%) provinces. Notably, 94.8% of KL64 strains maintained intact pLVPK plasmids with high aerobactin carriage (60.5%), while KL47 exhibited frequent plasmid fusion (58.8% with IncFIB[pNDM-Mar]) or chromosomal integration (41.4%), resulting in lower virulence potential (27.3% aerobactin+). Genomic analysis revealed KL64's superior plasmid stability (71.2% gene retention vs. KL47's 43.6%) and clinical correlation with severe outcomes (OR = 2.34, 95%CI 1.67-3.28).</p><p><strong>Conclusion: </strong>The ST11-KL64 subclone's epidemiological success stems from stable pLVPK plasmid maintenance, enabling simultaneous carbapenem resistance and hypervirulence. These findings highlight the urgent need for genomic surveillance targeting plasmid-mediated virulence in CRKP outbreaks, particularly in critical care settings where horizontal gene transfer may accelerate strain evolution.</p>","PeriodicalId":14318,"journal":{"name":"International Microbiology","volume":" ","pages":""},"PeriodicalIF":2.9,"publicationDate":"2026-09-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148879976","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}