Fems Microbiology Letters最新文献

{"title":"Growth-rate dependent response of mycobacteria to relief of inhibition by a bacteriostatic antibiotic.","authors":"Priyanka Chauhan, Frank J Bruggeman","doi":"10.1093/femsle/fnag048","DOIUrl":"10.1093/femsle/fnag048","url":null,"abstract":"<p><p>Pathogenic bacteria generally resume growth upon removal of bacteriostatic antibiotics. However, it is poorly understood how pre-growth conditions influence (i) the lag time before growth resumption and (ii) induction of antibiotics tolerance upon removal of the antibiotics. To study these traits in Mycobacterium smegmatis, we used a stringent-response-inducing bacteriostatic inhibitor, serine hydroxamate (SHX), which mimics a growth-rate-reducing antibiotic. We find that SHX-induced, growth-arrested cells display characteristics typical of persister cells, i.e. low ATP levels, increased antibiotic tolerance, and delayed growth-recovery. Single-cell microscopy shows morphological changes in SHX-treated cells (elongation and polar swelling) and growth resumption upon SHX removal after a lag time. During this lag time, the cells displayed increased antibiotic survival, which remained evident after complete recovery from SHX stress. Varying the SHX dose, exposure time, and pre-exposure growth rate indicated that the duration of the lag phase depends on the SHX exposure time and the prior growth rate, not on the SHX dose. The lag phase could be shortened by over two-fold with the addition of amino acids, pyruvate, or spent medium, indicating that growth inhibition induces a relievable metabolic bottleneck. Our findings align with studies of other (evolutionarily distant) microorganisms, suggesting that mycobacteria may be limited by similar phenotypic trade-offs associated with adaptive responses to sudden growth rate reductions.</p>","PeriodicalId":12214,"journal":{"name":"Fems Microbiology Letters","volume":" ","pages":""},"PeriodicalIF":2.0,"publicationDate":"2026-01-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13155453/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147728736","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":"Chemical synthesis and evaluation of the antibacterial activity of the amino chalcone in efflux pump-carrying strains.","authors":"Isydório Alves Donato, Cristina Rodrigues Dos Santos Barbosa, Antonio Henrique Bezerra, Suieny Rodrigues Bezerra, Ray Silva Almeida, Cícera Datiane de Morais Oliveira Tintino, Isaac Moura Araújo, Ana Luiza Fernandes Romão, André Nilton Silva Dias, Francisco Rogenio da Silva Mendes, Jayza Maria Lima Dias, Paulo Nogueira Bandeira, Roberto Lima de Albuquerque, Hélcio Silva Dos Santos, Henrique Douglas Melo Coutinho, Saulo Relison Tintino, Francisco Assis Bezerra da Cunha","doi":"10.1093/femsle/fnag033","DOIUrl":"10.1093/femsle/fnag033","url":null,"abstract":"<p><p>Given the ability of microorganisms to develop drug resistance at a faster pace than the development of new drugs, it becomes urgent to seek alternatives capable of restoring the efficacy of antibiotics, especially against pathogens such as Staphylococcus aureus, known for its versatility in expressing resistance mechanisms. Synthetic chalcones have been extensively investigated as efflux pump inhibitors due to their structural flexibility and ease of chemical modification. Can cite studies that show chalcones derived from Croton anisodontus for their ability to inhibit the NorA and MepA efflux pumps in S. aureus strains (1199B and K2068) and studies chalcones act as inhibitors of the NorA efflux pump in whole cells and everted membrane vesicles of S. aureus. Among these mechanisms, the NorA and MepA efflux pumps stand out, as they are responsible for expelling antibiotics from the bacterial cell interior. In this context, the present study investigated the potential of the chalcone (E)-1-(3-aminophenyl)-3-(4-chlorophenyl)prop-2-en-1-one as a possible inhibitor of these efflux systems. Initial screening was conducted through in silico studies, followed by in vitro assays, determination of minimum inhibitory concentration (MIC), and fluorescence tests using ethidium bromide EtBr and SYTOX Green. Molecular docking results revealed that this chalcone interacts with amino acid residues described in the literature as essential for efflux pump activity (Glu222 and Phe303 in NorA; Tyr35 and Met172 in MepA). The binding distances and energies obtained were consistent with potential inhibitory activity, suggesting that chalcone may interfere with the functionality of these proteins. In vitro assays showed a significant reduction in the MIC of antibiotics such as norfloxacin and ciprofloxacin in resistant strains, indicating a potentiating effect. Furthermore, fluorescence tests demonstrated increased retention of ethidium bromide by up to 736.3% for NorA and 234.8% for MepA, supporting the inhibition of efflux pumps. Increased bacterial membrane permeability was also observed, evidenced by an increase in SYTOX Green fluorescence by 70-855%. Although the results demonstrate the potential of chalcone as a therapeutic adjuvant, the ADMET analyses revealed toxicological alerts that require further investigation. These findings suggest that rational structural modifications may be necessary to ensure its safety and efficacy in combating resistant bacterial infections.</p>","PeriodicalId":12214,"journal":{"name":"Fems Microbiology Letters","volume":" ","pages":""},"PeriodicalIF":2.0,"publicationDate":"2026-01-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147510733","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":"Real-Lab-Day as an innovative approach to optimize and validate laboratory protocols for higher education practical classes: focus on bacterial pathogenicity.","authors":"Lara Nardi Baroni, Bárbara Rodrigues Cintra Armellini, Samantha Carvalho Maia Brito, Rita de Cássia Café Ferreira, Ana Carolina Ramos Moreno","doi":"10.1093/femsle/fnag042","DOIUrl":"10.1093/femsle/fnag042","url":null,"abstract":"<p><p>The Real-Lab-Day active learning methodology is an innovative approach aimed at deepening undergraduate students' understanding of the scientific process by integrating theory with practical laboratory experience in microbiology. This study aimed to reassess the educational impact of Real-Lab-Day ten years after its initial implementation and to explore its potential for optimizing experimental microbiology protocols. Undergraduate students participated in authentic laboratory experiments under the supervision of graduate mentors. To assess the impact of the activity, formative questionnaires were administered to evaluate students' perceptions of learning, engagement, and motivation. In parallel, the methodology was employed to optimize a bacterial pathogenicity protocol using enteroinvasive Escherichia coli (EIEC) as a model organism. Our data revealed sustained student approval and confirmed the effectiveness of the methodology in consolidating theoretical knowledge, developing practical and cognitive skills, and fostering interest in microbiological research. Furthermore, Real-Lab-Day enabled the successful optimization of bacterial invasion and dissemination protocol. Overall, Real-Lab-Day emerges as a multifunctional pedagogical strategy that effectively connects teaching and research. It enhances student learning experiences while also contributing to the optimization and validation of experimental protocols for use in practical classes. The methodology aligns with contemporary higher education practices and holds strong potential for future educational research.</p>","PeriodicalId":12214,"journal":{"name":"Fems Microbiology Letters","volume":" ","pages":""},"PeriodicalIF":2.0,"publicationDate":"2026-01-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147688907","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":"Genomic insights into Candidatus Argiopiplasma dusa, a bacterial symbiont of the wasp spider Argiope bruennichi.","authors":"Larissa M Busch, Monica M Sheffer, Nina Dombrowski, Henrik Krehenwinkel, Stefan Prost, Anja Spang, Gabriele Uhl, Tim Urich, Katharina J Hoff, Mia M Bengtsson","doi":"10.1093/femsle/fnag103","DOIUrl":"10.1093/femsle/fnag103","url":null,"abstract":"<p><p>Bacterial symbionts were shown to have diverse but significant impacts on the fitness of their host in insects, but little is known on the symbionts of spiders and their interactions with their hosts. Here, we assembled and investigated the circular 575 kb genome of Candidatus Argiopiplasma dusa, a novel bacterial symbiont of the wasp spider Argiope bruennichi. Phylogenomic analysis placed this species within the phylum Mycoplasmatota, in a poorly characterized clade that may represent a new order-level lineage or affiliate with the Mycoplasmatales order. With 559 predicted genes, the genome is relatively small compared to other Mycoplasmatota genomes (on average 969 genes) and has a low GC content of ∼24%. While the genome encodes genes for proteins involved in glycolysis and fermentative acetate production, it revealed minimal biosynthetic capabilities with pathways for nucleotide, amino acid, and vitamin biosynthesis being absent in Ca. Argiopiplasma dusa. This suggests a metabolic dependence and an endosymbiotic lifestyle within the spider host. The symbiont was detected in A. bruennichi populations across the distribution range of the spider but appears to be absent in certain populations.</p>","PeriodicalId":12214,"journal":{"name":"Fems Microbiology Letters","volume":" ","pages":""},"PeriodicalIF":2.0,"publicationDate":"2026-01-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13599016/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149016078","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":"Genomic characterization of clinical Burkholderia semiarida SYBS718, a Burkholderia cepacia complex strain isolated from an immunocompromised patient.","authors":"Huaxiong Zhu, Hao Li, Lixia Xu, Xiaoying Fu, Chongzhen Wang, Shan Zhong, Licheng Wang","doi":"10.1093/femsle/fnag117","DOIUrl":"10.1093/femsle/fnag117","url":null,"abstract":"<p><p>Burkholderia semiarida, a plant-pathogenic species within the Burkholderia cepacia complex (Bcc), has emerged as a worrying opportunistic pathogen causing serious respiratory infections in patients with cystic fibrosis (CF). In this study, strain SYBS718 was isolated from the blood and sputum of an immunocompromised patient. Conventional MALDI-TOF mass spectrometry and 16S rRNA sequencing misidentified this isolate as Burkholderia cenocepacia, whereas whole-genome sequencing enabled accurate species confirmation. Genomic analysis predicted a total of 569 virulence factors, 11 antibiotic resistance genes, and 1112 type III secretion system effector proteins related genes through the core databases of VFDB, CARD, and TS33. The virulence factors mainly include type VI secretion system (T6SS), type III secretion system (T3SS), iron uptake system, flagella, and type IV pili (TFP), which are associated with bacterial colonization, invasion, and pathogenicity. And the antibiotic resistance genes are primarily associated with fluoroquinolone, tetracycline, and aminoglycoside antibiotics. This study is the first to perform comprehensive genomic characterization of a clinical B. semiarida isolate. Our findings reveal the limitations of routine Bcc identification, and provide fundamental genomic data for further clinical and mechanistic research on this emerging opportunistic pathogen.</p>","PeriodicalId":12214,"journal":{"name":"Fems Microbiology Letters","volume":" ","pages":""},"PeriodicalIF":2.0,"publicationDate":"2026-01-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149080264","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":"Integrating morphological and etymological analysis in microbiology teaching: a pedagogical approach to vocabulary acquisition.","authors":"Nadine Yeramian, Daniel Pérez-Alonso, Lorena Casado-Martín, Mariana Alves-Elois, Rebeca Salguero-Campomar, Álvaro Cañete-Reyes, David Rodríguez-Lázaro","doi":"10.1093/femsle/fnag124","DOIUrl":"10.1093/femsle/fnag124","url":null,"abstract":"<p><p>Microbiology students often struggle with the extensive and specialized terminology of the discipline, frequently relying on rote memorization rather than understanding word structure, which limits long-term retention. This study investigated the integration of morphological and etymological analysis into microbiology courses as a tool to support vocabulary learning. Surveys conducted at the end of the semester over three academic years revealed that students generally accepted the approach, reported an improved ability to memorize and understand terms, and indicated that they would use it in the future to decode unfamiliar scientific words. These results suggest that morpheme-based instruction represents a practical and promising strategy for enhancing comprehension and the retention of microbiological terminology.</p>","PeriodicalId":12214,"journal":{"name":"Fems Microbiology Letters","volume":" ","pages":""},"PeriodicalIF":2.0,"publicationDate":"2026-01-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149127094","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":"Characterization of ammonium transporters in the dinoflagellate Alexandrium catenella (Group I).","authors":"Atsushi Kobiyama, Shinkichi Okiyama, Yuichiro Yamada","doi":"10.1093/femsle/fnag120","DOIUrl":"10.1093/femsle/fnag120","url":null,"abstract":"<p><p>Alexandrium catenella (Group I) causes paralytic shellfish poisoning. Nitrogen is a critical component for both growth and toxin production in A. catenella, and recent studies have indicated that A. catenella uses ammonium as a nitrogen source. However, the molecular mechanism underlying the transportation of ammonium in A. catenella has not been identified. In this study, we attempted to isolate and characterize the ammonium transporter (AMT) in A. catenella. cDNA cloning produced a number of AMT clones. To investigate the ammonium transport capability of A. catenella AMT (AlcAMT), we selected three representative cDNAs and the clones were inserted into expression vectors. These vectors were then transferred into an amt-deficient Schizosaccharomyces pombe transgenic yeast strain, and the resulting transformants were grown on a medium containing NH4Cl as the only nitrogen source. Following transformation, only yeast transformants carrying one of the three AMTs were able to grow on the medium, confirming its ability to transport ammonium. Sequence analysis of the three AMT variants revealed that the successful variant included a K residue at sequence position 450, while the other variants contained a T residue at the same position. Mutation analysis confirmed that K450 is important for the function of AlcAMT.</p>","PeriodicalId":12214,"journal":{"name":"Fems Microbiology Letters","volume":" ","pages":""},"PeriodicalIF":2.0,"publicationDate":"2026-01-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149106345","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 Type III Secretion System plasmid pPHDPT3 of Photobacterium damselae subsp. piscicida is stable in Australian isolates due to conserved non-repetitive genomic architecture.","authors":"Oleksandra Rudenko, Laura Baseggio, Andrew C Barnes","doi":"10.1093/femsle/fnag074","DOIUrl":"10.1093/femsle/fnag074","url":null,"abstract":"<p><p>Photobacterium damselae subsp. piscicida (Pdp) is a host-adapted primary pathogen impacting finfish aquaculture worldwide, whose virulence evolution is driven by the mobilome. The pPHDPT3 plasmid encoding a type III secretion system is critical for Pdp virulence but unstable in vitro in European and Japanese isolates. Here we show that a stable ancestral variant is conserved in Australian isolates. The elusive pPHDPT3 variant has undergone gene loss and accumulated a ∼5.5 kb quadruple direct repeat, which could explain plasmid loss via the classic dimer catastrophe scenario. In addition, we hypothesize that a 189-aa serine recombinase encoded within this repeat, and also on pPHDP10 plasmid, may act as a plasmid resolvase, with its frequent loss further exacerbating the dimer catastrophe.</p>","PeriodicalId":12214,"journal":{"name":"Fems Microbiology Letters","volume":" ","pages":""},"PeriodicalIF":2.0,"publicationDate":"2026-01-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13347740/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148307924","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":"Low bentonite biomass leads to inconsistent culture-based estimates of microbial abundances.","authors":"Rachel C Beaver, Cailyn M Perry, Chang Seok Kim, Josh D Neufeld","doi":"10.1093/femsle/fnag003","DOIUrl":"10.1093/femsle/fnag003","url":null,"abstract":"<p><p>Bentonite is an important component of deep geological repositories for long-term storage of used nuclear fuel. Studying the microbiology of bentonite exposed to various conditions is relevant because certain microorganisms (e.g. those that produce corrosive sulfide or gaseous metabolites) could lead to deterioration of engineered barrier components of the repository. In previous research, a high degree of variability in the abundance of culturable microorganisms among replicate samples has been observed. The purpose of this study was to test whether experimental technique (e.g. inadequate mixing of bentonite) or extremely low biomass represent mechanisms to explain such variability. Using a combination of cultivation- and DNA-based techniques to study six replicate hydrated bentonite microcosms, as well as six replicate bentonite aliquots originating from the same hydrated bentonite microcosm, the results of this study demonstrate that observed heterogeneity is likely not due to inadequate bentonite mixing. Instead, the data indicate that low biomass of as-received bentonite leads to unique populations of culturable bacteria associating with each sample, or to a lesser degree within different areas of a single bentonite sample used to establish a microcosm. Because some microorganisms that grow in bentonite are culturable under commonly used cultivation conditions and others are not, this can lead to differences in culture-based abundance estimates among replicate samples. Although cultivation is a useful technique to demonstrate viability of microorganisms in bentonite, the results of this study highlight the importance of a multifaceted experimental approach (i.e. coupling cultivation to DNA-based analysis) and careful analysis of replicates when working with such low biomass samples.</p>","PeriodicalId":12214,"journal":{"name":"Fems Microbiology Letters","volume":" ","pages":""},"PeriodicalIF":2.0,"publicationDate":"2026-01-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12850535/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145958955","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":"Experimental evidence for the absence of a functional gut microbiome in the solitary bee Megachile tosticauda.","authors":"Elisabeth Williamson, Kelly Hill, Raphael Eisenhofer, Katja Hogendoorn","doi":"10.1093/femsle/fnag012","DOIUrl":"10.1093/femsle/fnag012","url":null,"abstract":"<p><p>The eusocial honey bee is a model for insect microbiome research, with socially transmitted gut communities that play key roles in health and development. In contrast, solitary bees lack social transmission pathways and often have an environmentally acquired microbiome, which may or may not be functionally important. Using 16S rRNA gene metabarcoding, previous work has described the bacterial communities in the solitary resin bee Megachile tosticauda pollen provisions, brood, and adult bees, but their functional significance has yet to be studied. Here, we investigate the importance of live bacteria for larval development and survival with an antibiotic-feeding experiment, and test whether bacteria are present in adult guts using scanning electron microscopy. Removing live bacteria in the food and gut of feeding larvae had no significant effect on survival or growth. Microscopy revealed no bacterial colonization of the adult gut, and the dominant taxon detected in larval pollen could not be cultured under targeted conditions. These results suggest an absence of a beneficial gut microbiome in M. tosticauda. Based on our findings, we propose that some bacteria detected by DNA-based methods in M. tosticauda may represent relic DNA, surface-associated or transient bacteria. Our findings highlight fundamental differences in the bacterial associations between social and solitary bees.</p>","PeriodicalId":12214,"journal":{"name":"Fems Microbiology Letters","volume":" ","pages":""},"PeriodicalIF":2.0,"publicationDate":"2026-01-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13016869/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146085009","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}