Microbiology-Sgm最新文献

{"title":"Chromosomal resistance mutations facilitate acquisition of multidrug-resistant plasmids in <i>Escherichia coli</i>.","authors":"Khadija-Siddiqa N Hanga, Michael A Brockhurst, Michael J Bottery","doi":"10.1099/mic.0.001599","DOIUrl":"10.1099/mic.0.001599","url":null,"abstract":"<p><p>Bacteria can gain multiple resistance mechanisms in a single step by the acquisition of multidrug-resistant (MDR) plasmids, but it is unclear how antibiotic selection during the acquisition of MDR plasmids affects the evolution of additional resistance mechanisms. Through conjugating separate extended-spectrum <i>β</i>-lactamase (ESBL)- and carbapenemase-producing MDR plasmids into plasmid-naive <i>Escherichia coli</i> hosts, we examine the effects of acquisition of a single plasmid or co-acquisition of multiple plasmids upon fitness costs, resistance and subsequent genomic adaptation. We show that acquisition of pOXA-48, encoding OXA-48 carbapenemase, is associated with highly variable fitness costs and levels of resistance to ertapenem in transconjugants independent of the presence of pLL35. This phenomenon was not observed during the acquisition of ESBL CTX-M-15-encoding pLL35 alone. Within a single growth cycle, transconjugants receiving pOXA-48 rapidly gained parallel mutations affecting the membrane porin OmpF, or its regulators OmpR or EnvZ. These chromosomal mutations were not compensatory for the fitness costs imposed by the plasmid, nor did they provide significant increases in resistance to carbapenems in the absence of the pOXA-48. Rather, they acted synergistically with the plasmid-encoded carbapenemase, which alone only provided marginal resistance, together providing high-level resistance to ertapenem. Such rapid evolutionary processes may play an important role in plasmid dynamics within environments with strong antibiotic selection for plasmid-encoded antimicrobial resistance genes (ARGs), particularly when these ARGs provide only marginal resistance.</p>","PeriodicalId":49819,"journal":{"name":"Microbiology-Sgm","volume":"171 9","pages":""},"PeriodicalIF":3.5,"publicationDate":"2025-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145138800","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":"<i>Enterococcus faecalis</i> requires unsaturated fatty acids to overcome toxicity of environmental saturated fatty acids.","authors":"Qi Zou, Huijuan Dong, John E Cronan","doi":"10.1099/mic.0.001602","DOIUrl":"10.1099/mic.0.001602","url":null,"abstract":"<p><p><i>Enterococcus faecalis</i> synthesizes phospholipids from either <i>de novo</i> synthesized or exogenous fatty acids. However, environmental saturated fatty acids are toxic to <i>E. faecalis</i>. The mechanism of toxicity is unknown. We report that saturated acids block growth by efficiently repressing transcription of the fatty acid biosynthesis (<i>fab</i>) genes, resulting in blockage of the synthesis of unsaturated fatty acyl chains. Saturated fatty acid toxicity depends on the chain length of the acyl chains. Growth was restored in the presence of toxic saturated fatty acids by the increased <i>de novo</i> unsaturated fatty acid synthesis, resulting from the deletion of the <i>fabT</i> gene, the repressor that regulates (<i>fab</i>) gene transcription. The addition of unsaturated fatty acids to the medium also restored growth in the presence of toxic saturated fatty acids. Overexpression of AcpA, the fatty acid synthesis acyl carrier protein, also gave increased <i>de novo</i> synthesis of unsaturated fatty acids and restored growth.</p>","PeriodicalId":49819,"journal":{"name":"Microbiology-Sgm","volume":"171 9","pages":""},"PeriodicalIF":3.5,"publicationDate":"2025-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12408189/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144976383","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Disulphide bond-forming enzymes in clostridial species.","authors":"Claudia Antonika, Jocelyne Mendoza, Cristina Landeta","doi":"10.1099/mic.0.001603","DOIUrl":"10.1099/mic.0.001603","url":null,"abstract":"<p><p>Disulphide bond formation is critical for the folding and stability of proteins involved in bacterial cell envelope processes yet remains understudied in clostridial pathogens. While a few Clostridia-derived toxins and virulence factors are known to depend on disulphide bonds, the enzymes catalysing their formation are poorly characterized. Here, we performed a bioinformatic search to identify ten putative disulphide bond-forming enzymes in Clostridia. We cloned and codon-optimized these genes, testing their ability to complement <i>Escherichia coli dsb</i> mutants. Our analysis revealed a VKOR homologue, a VKOR-DsbA fusion and three DsbA homologues capable of complementing <i>E. coli dsb</i> mutants. Notably, <i>Clostridium botulinum</i> DsbA functioned independently of a regenerating partner, with its activity recycled by glutathione disulphide or ergothioneine. In contrast, <i>Clostridium tetani</i> and <i>Clostridioides difficile</i> DsbA proteins required <i>E. coli</i> DsbB for regeneration, suggesting reliance on distinct thiol or enzyme partners. Understanding oxidative protein folding in Clostridia could reveal new targets for antibacterial intervention.</p>","PeriodicalId":49819,"journal":{"name":"Microbiology-Sgm","volume":"171 9","pages":""},"PeriodicalIF":3.5,"publicationDate":"2025-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12453122/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145056230","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Common food preservatives induce an oxidative stress response in <i>Salmonella enterica</i> serovar Typhimurium.","authors":"Emma R Holden, Joshua C I Horton, Mark A Webber","doi":"10.1099/mic.0.001609","DOIUrl":"10.1099/mic.0.001609","url":null,"abstract":"<p><p>Despite their frequent use, the mechanisms of action of common food preservatives are poorly understood. As there is a drive to develop alternative preservatives, understanding the mechanisms of action of current preservatives can inform the development of novel food preservatives to ensure their efficacy. Here, we used TraDIS-<i>Xpress</i>, a large-scale, genome-wide unbiased screen to determine the mechanisms of action of common food preservatives by determining the genes that affect preservative susceptibility in <i>Salmonella enterica</i> serovar Typhimurium. We identified genes associated with central metabolism and oxidative stress responses that were important for all four preservatives. Formate dehydrogenase activity and synthesis was crucial for survival in the presence of both sodium chloride and potassium chloride. We found some preservative-specific effects on pathogen susceptibility, for example, LPS synthesis which improved survival upon exposure to sodium nitrite but harmed survival when exposed to sodium chloride or potassium chloride. This research expands our understanding of how some current preservatives act and can inform the effective use of preservatives in current and emerging food products to ensure high standards of food safety.</p>","PeriodicalId":49819,"journal":{"name":"Microbiology-Sgm","volume":"171 9","pages":""},"PeriodicalIF":3.5,"publicationDate":"2025-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12440568/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145070903","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Fluconazole resistance and <i>CDR1</i> expression in <i>Candida albicans</i> mediated by the hyperactive Tac1-5 transcriptional activator requires Tlo proteins.","authors":"Wen Jun Lim, Brenda Lee, Zahra Farrington, Abed Alkarem Abu Alhaija, Alastair B Fleming, Derek J Sullivan, Gary P Moran","doi":"10.1099/mic.0.001594","DOIUrl":"https://doi.org/10.1099/mic.0.001594","url":null,"abstract":"<p><p><i>Candida albicans</i> is an opportunistic fungal pathogen associated with superficial and systemic infections in humans. Azole antifungal resistance in <i>C. albicans</i> is of clinical concern, and both oral and systemic <i>Candida</i> infections can be difficult to treat due to the lack of alternative antifungal drugs. Expression of a hyperactive form of the transcription factor Tac1 is a major contributor to azole resistance in <i>C. albicans</i> isolates resulting in the increased expression of the azole efflux pump Cdr1. In this study, we investigated whether the Mediator tail component Med2, encoded by the expanded (n=14) <i>TLO</i> gene family of <i>C. albicans</i>, was required for Tac1 activity. A homozygous <i>TAC1-5</i> gain-of-function point mutation was introduced into WT, <i>tlo</i>Δ and <i>med3</i>Δ strains of <i>C. albicans</i> which enables them to express hyperactive Tac1. qRT-PCR analysis revealed that <i>tlo</i>Δ-<i>TAC1-5</i> had reduced basal and fluphenazine-induced <i>CDR1</i> expression relative to WT-<i>TAC1-5</i> strains and exhibited reduced levels of resistance to fluconazole and terbinafine. Individual copies of representatives from each of the alpha, beta and gamma <i>TLO</i> clades were reintroduced into <i>tlo</i>Δ-<i>TAC1-5</i> to investigate their ability to restore Tac1-activated resistance. These studies show that alpha and beta <i>TLO</i> genes could restore fluconazole resistance in the <i>tlo</i>Δ-<i>TAC1-5</i> background, whereas gamma clade genes did not result in any detectable phenotypic complementation. Transcript profiling showed that reintroduction of <i>TLO</i>α<i>1</i> led to increased expression of <i>TAC1-5</i>-activated genes such as <i>CDR1</i>. Further analysis using ChIP-qPCR revealed that Tloα1 localizes to the drug response element which is the site where Tac1 binds to the <i>CDR1</i> promoter. These data have identified that the <i>TLO</i> gene family is required for the expression of Tac1-mediated fluconazole resistance. However, this effect is confined to members of the alpha and beta, but not the gamma, <i>TLO</i> clades.</p>","PeriodicalId":49819,"journal":{"name":"Microbiology-Sgm","volume":"171 9","pages":""},"PeriodicalIF":3.5,"publicationDate":"2025-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12401524/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144976412","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Microbial Primer: Biosurfactants - the ABCs of microbial surface-active metabolites.","authors":"Maude Dagenais Roy, Eric Déziel","doi":"10.1099/mic.0.001604","DOIUrl":"10.1099/mic.0.001604","url":null,"abstract":"<p><p>Microbial surfactants (biosurfactants) are low-molecular-weight amphiphilic secondary metabolites synthesized by a wide range of micro-organisms, including bacteria, yeasts and fungi. These compounds reduce surface and interfacial tension, promote emulsification and self-assemble into supramolecular structures such as micelles. Their remarkable structural diversity reflects the metabolic complexity of their microbial producers. In this primer, we outline shared features across biosurfactant-producing organisms, focusing on biosynthetic pathways, biological functions and regulatory mechanisms. The study of biosurfactants lies at the intersection of ecological, biotechnological and medical research, offering valuable insights into microbial ecology and promising avenues for sustainable innovation.</p>","PeriodicalId":49819,"journal":{"name":"Microbiology-Sgm","volume":"171 9","pages":""},"PeriodicalIF":3.5,"publicationDate":"2025-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12413298/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145001884","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Two putative <i>Enterococcus faecalis fabG</i> genes do not encode β-ketoacyl-acyl carrier protein reductases.","authors":"Qi Zou, Huijuan Dong, John E Cronan","doi":"10.1099/mic.0.001610","DOIUrl":"10.1099/mic.0.001610","url":null,"abstract":"<p><p><i>Enterococcus faecalis</i> encodes three putative <i>Escherichia coli</i> β-ketoacyl-acyl carrier protein (ACP) reductases (FabG). The <i>fabG1</i> gene is located within the operon that encodes most of the fatty acid synthesis genes, while the putative <i>fabG2</i> and <i>fabG3</i> genes are located elsewhere on the chromosome. The genes were tested for the ability to complement the growth of an <i>E. coli fabG</i>(Ts) strain at the non-permissive temperature. Of the three genes, only <i>E. faecalis</i> FabG1 restored growth at high temperature. Moreover, deletion of the <i>E. faecalis fabG1</i> gene resulted in an auxotrophic strain that required oleic acid for growth, arguing that it encodes the only functional β-ketoacyl-ACP reductase. Growth of this strain in the absence of fatty acid was restored by plasmid-borne <i>fabG1</i>, but not by plasmids encoding either <i>fabG2</i> or <i>fabG3</i>. Although <i>E. faecalis fabG2</i> has a putative binding site for the FabT transcription factor at the 5' end of the coding region, expression of a transcriptional fusion with β-galactosidase was unaffected by deletion of <i>fabT</i> or by fatty acid supplementation.</p>","PeriodicalId":49819,"journal":{"name":"Microbiology-Sgm","volume":"171 9","pages":""},"PeriodicalIF":3.5,"publicationDate":"2025-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145132350","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":"Increase in lipid portion of <i>Phycomyces blakesleeanus</i> biomass induced by vanadate uptake and accumulation.","authors":"Jovana M Lukičić, Milena Dimitrijević, Milan Žižić, Željka Višnjić Jeftić, Miroslav Živić, Tijana Cvetić Antić, Marina Stanić","doi":"10.1099/mic.0.001615","DOIUrl":"10.1099/mic.0.001615","url":null,"abstract":"<p><p>Fungi are ubiquitous micro-organisms involved in various environmental processes, with a particularly important role in the transformation of metals and minerals, bioremediation and biomining. Filamentous fungus <i>Phycomyces blakesleeanus</i> is an interesting model for investigating the interaction of fungi with various ecological factors, such as heavy metals, due to the ease of its cultivation and fast growth. The present study deals with the interaction of increasing vanadate [V(V)] concentrations with the mycelium of <i>P. blakesleeanus</i> in three distinct growth phases: mid-exponential, late exponential and stationary phase. Mid- and late-exponential phase mycelium had a V content of nearly 1% after 24 h incubation with 10 mM V(V), and the uptake of V(V) was accompanied by increased phosphorus uptake with both 5 and 10 mM V(V). Fourier Transform Infrared spectroscopy showed the increase of lipid portion in biomass compared to proteins and carbohydrates mainly with ageing, but also with vanadate treatment. <i>P. blakesleeanus</i> is tolerant to high V(V) concentrations, and this study suggests its potential as V accumulator. In addition, the increase in lipid content calls for a closer examination of lipid content and fatty acid composition after V(V) treatment and determination of their potential industrial utilization.</p>","PeriodicalId":49819,"journal":{"name":"Microbiology-Sgm","volume":"171 9","pages":""},"PeriodicalIF":3.5,"publicationDate":"2025-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145132331","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":"The interaction between IL-17 and gut microbiota contributes to cholestatic liver disease in children.","authors":"Shu-Li He, Zhuo-Heng Li, Juan Li, Ying Li","doi":"10.1099/mic.0.001608","DOIUrl":"10.1099/mic.0.001608","url":null,"abstract":"<p><p>The pathogenesis of cholestatic liver disease (CLD) is unknown, but the influence of gut microbiota and inflammation cannot be ignored. In this study, we attempted to provide theoretical insights for the diagnosis and treatment of CLD in children by analysing the association between gut microbiota, IL-17 levels and clinical characteristics. This research involved 21 children diagnosed with CLD and 11 healthy controls. Blood and faecal samples were collected from these participants. Blood samples underwent analysis for clinical indicators and IL-17 concentrations. Gut microbiota was examined through 16S rRNA gene sequencing for identification and functional prediction. A positive correlation between IL-17 levels and clinical parameters (total bile acids, alanine aminotransferase, aspartate aminotransferase and triglycerides) in children with CLD was observed. Notably, children with CLD exhibited reduced diversity and disturbances in gut microbiota, highlighted by a severe decrease of <i>Bacteroidota</i> (genus <i>Bacteroides</i>). Moreover, increased relative abundance of secondary bile acid-promoting (e.g. <i>Clostridium</i>, <i>Enterococcus</i> and <i>Bifidobacterium</i>) and deleterious (e.g. <i>Escherichia-Shigella</i> and <i>Streptococcus</i>) flora in the intestinal flora of children with CLD was positively correlated with IL-17, leading to increased inflammation and CLD aggravation. Functional predictions of gut microbiota revealed higher concentrations of l-asparagine transporter, ABC-type polar amino acid transport system and glycolysis II (from fructose 6-phosphate) functions, while the function of the Na⁺-driven multidrug efflux pump was decreased. In conclusion, children suffering from CLD exhibit significant gut microbiota disturbances, particularly a severe decrease in <i>Bacteroidota</i> (genus <i>Bacteroides</i>). Dysbiosis of the gut microbiota and elevated levels of IL-17 mutually reinforce each other, together mediating the onset and progression of CLD.</p>","PeriodicalId":49819,"journal":{"name":"Microbiology-Sgm","volume":"171 9","pages":""},"PeriodicalIF":3.5,"publicationDate":"2025-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12453119/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145071049","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Phosphate sensing by PhoPR regulates the cytotoxicity of <i>Staphylococcus aureus</i>.","authors":"Nathanael Palk, Tarcisio Brignoli, Marcia Boura, Ruth C Massey","doi":"10.1099/mic.0.001606","DOIUrl":"10.1099/mic.0.001606","url":null,"abstract":"<p><p><i>Staphylococcus aureus</i> has evolved a complex regulatory network to coordinate expression of virulence factors, including cytolytic toxins, with host environmental signals. Central to this network are two-component systems (TCSs), in which a histidine kinase senses an external signal and activates a response regulator via phosphorylation, leading to changes in gene expression. Using a comprehensive screen of transposon mutants in each of the non-essential histidine kinase and response regulator genes in <i>S. aureus</i>, we demonstrate that 11 of these 16 systems regulate cytotoxicity. Further characterization of the phosphate-sensing PhoPR system revealed that PhoP affects cytotoxicity in a manner mediated through the Agr quorum-sensing system. Notably, we found that unphosphorylated PhoP is an activator of Agr activity, whilst phosphorylated PhoP also acts as a weak activator of Agr activity in high-phosphate environments but as a repressor in low-phosphate environments. Furthermore, overexpression of PhoP resulted in upregulation of <i>α</i>-type phenol-soluble modulins, which may also contribute to the cytotoxicity phenotype observed in the <i>phoP</i> mutant. Overall, we have demonstrated that phosphate sensing through PhoPR is a novel regulator of cytotoxicity in <i>S. aureus</i>. Moreover, our study challenges the canonical model of TCSs as simple on/off systems and highlights the importance of unphosphorylated response regulators in gene regulation.</p>","PeriodicalId":49819,"journal":{"name":"Microbiology-Sgm","volume":"171 9","pages":""},"PeriodicalIF":3.5,"publicationDate":"2025-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12404567/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144976372","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}