Fems Microbiology Letters最新文献

Shiga toxin (Stx) is the primary virulence factor of Shiga toxin-producing Escherichia coli (STEC). Stx is categorized into Stx1 and Stx2 and further classified into several subtypes based on amino acid sequence variations. During routine surveillance of STEC isolates in Japan, we identified strain 2021H102 which harbored an uncommon stx subtype. Whole genome sequencing combined with matrix-assisted laser desorption/ionization-time of flight mass spectrometry analysis revealed that 2021H102 was a Stx2j-producing E. coli. Despite similarity among the sequences of Stx2j encoding prophages, phylogenetic analysis revealed that stx2j-positive E. coli genomes are diverse. 2021H102 clustered with genomes identified in the United States by core-genome single nucleotide variant-based phylogenetic analysis, implying that 2021H102 may have been an imported case. Several detection PCR primers failed to amplify stx2j, implying that stx2j-positive STEC might not be detected in some clinical laboratories. To our knowledge, this is the first report of Stx2j-producing E. coli isolated from outside of North American continent.

Pulmonary infection is one of the major health problems worldwide, with common pathogens including viruses, bacteria and fungi. During pulmonary infection, exosomes secreted by different immune cells serve as important communication mediators between cells and have the ability to regulate the immune system. Exosomes regulate lung immune responses by carrying bioactive molecules, including miRNA, proteins and lipids, initiating and inhibiting inflammatory responses, pathogen clearance, and immune tolerance. This article discusses multiple roles of exosomes in regulating the function of lung-resident innate immune cells (epithelial cells, macrophages, and neutrophils) and their potential effects in infectious diseases of the lung. In addition, the existing research has described the prospects of exosomes in immunotherapy. This review aims to summarise their role in the diagnosis and treatment of pulmonary infection in order to clarify the role and mechanism of exosomes in pulmonary infectious diseases.

This review focuses on the role of C-type lectin receptors (CLRs) in inflammatory bowel disease (IBD). It outlines their classification, structural features, and functional mechanisms within intestinal immunity. The article comprehensively examines recent advances in understanding the contributions of specific CLRs-including Dectin-1, Mincle, Dectin-3, and the mannose receptor (MR/CD206)-to IBD pathogenesis, particularly their functions in microbial recognition, immune cell activation, and the regulation of inflammatory responses. Finally, the review addresses current research challenges and future directions, with the aim of providing deeper insights into disease mechanisms and facilitating the development of novel CLR-targeted therapies.

We developed a STEAM (Science, Technology, Engineering, Arts and Mathematics) outreach program that integrates tardigrade biology with smartphone microscopy and 3D printing in a public science program hosted by the Kanagawa Institute of Industrial Science and Technology (KISTEC), Japan. Building on prior educational activities that introduced tardigrades mainly through conventional light microscopy, our approach links smartphone-based observation to the creation of 3D-printed models in a single, low-cost workflow. Between 2023 and 2025, five workshops were conducted with 249 students in grades 3-6. Participants collected local moss, recovered and enriched tardigrades from the samples, and observed their revival from anhydrobiosis using a smartphone microscope, followed by the creation of 3D-printed tardigrade models. Pre-activity questionnaires showed that although 92% of students had at least heard of tardigrades, fewer than 10% had ever used a smartphone microscope or a 3D printer, and about 90% reported high interest in these topics. Post-activity surveys indicated that interest remained high and increased modestly: 93-95% of students reported "very high" or "somewhat high" interest in tardigrades, smartphone microscopes, and 3-D printers, and 95% rated the workshop as "interesting" or "very interesting". In total, 74% (182/245) successfully located tardigrades in their own samples. Grade-level comparisons showed older students achieved higher understanding and fluency. This demonstrates that tardigrade biology, smartphone microscopy, and 3D printing provide an effective, low-cost microbiology outreach model for elementary education.

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.

Arcobacter butzleri, a foodborne pathogen of increasing public health relevance and associated with the gut of warm blooded animals is widely distributed in aquatic environments. Its association with the extensively studied faecal indicator, Escherichia coli remains unclear, yet is important for clarifying the ecology of pathogens and assessing risks. This study evaluated the prevalence and correlation between A. butzleri and E. coli in finfish, shellfish, and water sampled across multiple contamination points- markets, landing centres, and fishing vessels in Mumbai, India. A total of 70 samples (30 finfish, 30 shellfish, and 10 water) were tested using a miniaturized most probable number-quantitative polymerase chain reaction, which bypasses lengthy culture procedures and offers a reliable approach in the absence of a standard isolation method for A. butzleri. Arcobacter butzleri was present in 73% of the samples and E. coli in 81% samples indicating a high microbial burden of both organisms within this seafood ecosystem. Contamination varied by source, with market samples showing highest levels, followed by landing centres and lowest from on-board vessels, indicating post-harvest contamination influenced by nearshore water pollution. Regression analysis indicated positive correlation between A. butzleri and E. coli (ρ = 0.88, R² = 0.78, P < 0.001) and particularly robust associations were observed in shellfish and water matrices. This supports the close association of A. butzleri with sewage-impacted environments and its potential role as a supplementary indicator of fecal contamination.

Undergraduate courses in general microbiology often have high content and cognitive loads, making it challenging for students to achieve content mastery of the whole curriculum. Thus, the development of manageable mastery learning interventions that work within these contexts should benefit microbiology education broadly. In this work, we describe an oral examination intervention implemented within a modified Bloom's Learning for Mastery framework that significantly improves retention of course material across low-performing students in an undergraduate general microbiology course. The intervention consumed a relatively small amount of instructor time to administer (less than 15 min per student) and resulted in no distinguishable differences in knowledge retention on the final exam between students who initially mastered the content and did not participate in the intervention and those who participated in the intervention after failing to initially master the content. Students reported overwhelmingly positive experiences with the intervention, including increased perceptions of their own content retention, increased feelings of self-pride after participating in the intervention, and a general feeling that the intervention was fair. We conclude that oral examinations are an effective mastery learning tool in the microbiology classroom and can be easily implemented by the instructor alone in small- to medium-sized courses.

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.

Neisseria meningitidis (Nm), a commensal that colonizes the nasopharynx of 4.5%-24% of healthy humans, can cause invasive meningococcal disease (IMD). We hypothesized that distinct genotypic and/or phenotypic signatures might be found in carriage vs. invasive isolates. Carriage isolates were cultured from nasopharyngeal swabs (n = 267) collected from healthy students (aged 13-21 years) during the 2013 and 2014 school years in the Netherlands. Invasive isolates (n = 214) were cultured from all reported disease cases in the Netherlands from 2012 to 2014. Whole core genome sequences were determined for all isolates and comparisons of selected genotypic markers and phylogenomic associations between carriage and disease isolates were analyzed. While 30% of carriage isolates could not be assigned a genogroup, all the invasive isolates were successfully genogrouped. Genogroup B (MenB) predominated, representing 27% of carriage and 75% of IMD isolates. Sequence type (ST) complex diversity was dominated by four STs (ST-41/44, ST-213, ST-32, and ST-269) in both carriage and disease isolates. FHbp subfamily A variants were prevalent (79%) in carriage, whereas subfamily B variants were more frequent (69.6%) in disease. Carriage and IMD-causing Nm strains display similar ST and phylogenomic profiles; however, an increased FHbp subfamily B prevalence and an enhanced level of FHbp surface expression were noted in MenB disease-causing isolates.

Numerous Gram-negative bacteria possess N-acyl-L-homoserine lactone (AHL)-mediated quorum-sensing (QS) systems that regulate the activation of specific genes. Burkholderia plantarii causes rice seedling blight by producing the phytotoxin tropolone. In this study, we investigated multiple AHL-type QS systems in B. plantarii MAFF 301723T and their involvement in virulence regulation. MAFF 301723 harbors three AHL-mediated QS systems, designated plaI1/plaR1, plaI2/plaR2, and plaI3/plaR3. The plaI1/plaR1 system, which produces N-octanoyl-l-homoserine lactone, is functional and essential for swarming motility. When forced expression of plaI2 induces the biosynthesis of 3-OH-C10-HSL, it was suggested that expression is rarely observed in wild-type MAFF 301723. The plaI3 gene directs the synthesis of the putative C16:2-HSL, which is a rare AHL bearing two double bonds in the hexadecanoyl chain that has not been previously reported in Burkholderia spp. The plaI3/plaR3-QS system is crucial for tropolone production. These findings suggest that multiple QS systems collectively contribute to the complex virulence regulation of B. plantarii, thereby providing new insights into the development of QS-targeted biocontrol strategies for agriculture.