Fems Microbiology Letters最新文献

This study optimizes sustainable ectoine production in reduced salinity and minimal media to meet demands in pharmaceuticals, food, and cosmetics, isolating a halophilic bacterium 99.1% similarity to Halomonas smyrnensis from Sambhar Salt Lake. Optimization of ectoine production was performed using the one-variable-at-a-time method and response surface methodology, assessing variables such as carbon and nitrogen sources, incubation time, pH, temperature, inoculum density, agitation rate, and salinity. High-performance liquid chromatography confirmed total ectoine production, which increased from 0.54 to 6.5 g/l, a 12.03-fold enhancement compared to initial unoptimized conditions. The optimal ectoine yield by H. smyrnensis IIIM VA-6 was achieved after 72 h under conditions of 5% (w/v) salinity, 2.5 % monosodium glutamate, pH 5.0, 10.0 g/l lactose, and 250 rpm agitation, and characterized by Fourier transform infrared spectroscopy, nuclear magnetic resonance, and liquid chromatography mass spectrometry. This study represents a significant improvement in sustainable production of ectoine under reduced salinity conditions using a halophilic strain.

Periodontal disease is a chronic inflammatory condition primarily caused by Porphyromonas gingivalis (P. gingivalis), which plays a pivotal role in disease progression and biofilm formation. Conventional oral hygiene products often contain strong disinfectants, which can be unsuitable for children and older adults. Thus, identifying natural, low-irritant antibacterial agents is essential for safe and effective prevention. This study investigated fig (Ficus carica) leaves, an underutilized food biomass, as a source of antibacterial compounds. Ethanol extracts were fractionated using five solvents, and the ethyl acetate fraction showed the most potent growth inhibition against P. gingivalis, but not against Aggregatibacter actinomycetemcomitans. TLC and HPLC analyses revealed the presence of psoralen, bergapten, and several unidentified compounds. The ethyl acetate fraction was rich in polyphenols. Although individual HPLC-separated fractions showed limited activity, mixtures retained antibacterial effects, suggesting synergistic or additive interactions. The fraction also inhibited hyper-virulent P. gingivalis W83, Prevotella intermedia, and Staphylococcus epidermidis, but not Escherichia coli, indicating selective antibacterial activity. Known fig leaf compounds were not the main contributors to the observed effects. These findings suggest that fig leaf ethyl acetate extract may be a promising natural antibacterial agent for oral hygiene products, particularly targeting P. gingivalis, and may help prevent periodontal and related systemic diseases.

Infections with epidemic polymerase chain reaction ribotype (RT) 027 strains are characterized by higher mortality and morbidity and have caused outbreaks in North America and Europe. To date, RT027 isolates have not conclusively been shown in Brazil, although other clade 2 isolates have been identified. This case report discusses a 60-year-old patient, with medical history of colon adenocarcinoma, who developed a severe Clostridioides difficile infection (CDI) after chemotherapy, but showed a full recovery. The infection was caused by a C. difficile RT027 strain, demonstrating conclusively for the first time that this RT is present in Brazil. This case emphasizes the need for early CDI diagnosis of C. difficile in Brazilian hospitals for prompt treatment and notification.

The study of archaeal viruses is important for understanding microbial life in extreme environments. However, this study is difficult mainly because they predominantly exhibit a chronic lifestyle, where viral particles are released without causing host cell death. Therefore, conventional plaque assays, which are well-suited for studying lytic viruses, usually fail to detect chronically infecting viruses due to their nonlytic nature. To address this limitation, we developed an optimized plaque assay protocol for detecting chronically infecting viruses of haloarchaea, focusing on species within the Haloferax genus. By enhancing viral diffusibility and infectivity through adjustments in agar concentration and incubation temperature, this modified protocol improved plaque formation, enabling the detection of viruses that cause mild growth delays. We successfully demonstrate plaque formation for two chronically infecting viruses, Haloferax volcanii pleomorphic virus 1 (HFPV-1) and lemon-shaped virus of Haloferax strain Atlit 48 N (LSV-48 N), on representative Haloferax strains. This assay is an effective method for the detection and quantification of chronically infecting archaeal viruses, providing a new tool for discovering new viral families in extreme environments. Here, we present a high-sensitivity plaque assay protocol tailored specifically to detect archaeal viruses that produce chronic productive infections, which traditional methods have failed to identify. Our findings offer a novel tool that can be adapted for studying virus-host interactions within extreme environments, potentially expanding our understanding of the ecological roles and diversity of archaeal viruses. This protocol also represents a valuable advancement for microbiologists seeking to discover new archaeal viral viruses.

Whole-genome sequencing has transformed microbial genomics since the first bacterial genome was published in 1995. Advances in sequencing technology, together with decreasing costs, now enable high-resolution investigation of bacterial pathogens for epidemiological surveillance, and infection control. A major breakthrough has been the advent of third-generation long-read sequencing (LRS) platforms, such as Pacific Biosciences and Oxford Nanopore Technologies, which overcome the limitations of short-read sequencing by producing long continuous reads. LRS facilitates accurate de novo genome assembly, resolution of repetitive and structurally complex regions, and precise characterization of plasmids and other mobile genetic elements that frequently harbor antimicrobial resistance genes (ARGs). A particular strength of LRS lies in its ability to reveal the complete genomic architecture of ARGs, including their localization, copy number, and surrounding genetic environment. Such contextual information is essential, since e.g. the interpretation of antimicrobial resistance (AMR) depends not only on the presence of specific genes but also on their structural organization, mobility potential, and genomic integration. By contrast, LRS provides a reliable foundation for understanding AMR evolution and dissemination through both clonal expansion and horizontal gene transfer. Recent developments in bioinformatics, including dedicated tools for plasmid reconstruction, typing, and annotation, further enhance the analytical value of LRS and hybrid approaches. Beyond isolate-level analyses, LRS enables plasmid surveillance and the tracing of ARG transmission across strains, hosts, and healthcare settings. This review sets out to give readers a brief overview of LRS technology and its capabilities and outlines current approaches and tools to analyze bacterial plasmids.

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.

SMC (Structural Maintenance of Chromosomes) ATPase proteins are integral components of complexes bearing the same name, crucial for the spatial organization of DNA across diverse life forms, spanning bacteria, archaea, and eukaryotes. It is proposed that in bacteria, SMC complexes facilitate DNA compaction through loop extrusion and aid in the segregation of daughter nucleoids. In this paper, the properties of the SMC ATPase protein from Ureaplasma parvum were investigated by using a spectrum of methods, including conventional biochemical methods as well as advanced single-molecule techniques. Our findings reveal distinctive properties of this protein compared to its extensively studied homologue from Bacillus subtilis. Notably, our results suggest that U. parvum Smc ATPase facilitates DNA compaction even in the absence of ATP.

Aeration is a common pretreatment method to enhance biogas production via anaerobic digestion of waste organic feedstocks such as unused food. While impacts on downstream anaerobic digestion have been intensively investigated, the consequence of aeration on the microbial community in food waste has not been characterized. Food waste has a low pH resulting from the dominance of lactic acid bacteria within the Firmicutes phylum. This excludes other phylotypes with a higher potential to hydrolyse complex biopolymers in food waste. In this study, we reveal that aeration of macerated food waste results in a dramatic shift away from Firmicutes towards dominance of Proteobacteria that are better known for extracellular enzyme production. Given that hydrolysis is the rate limiting step in anaerobic digestion, this explains why aeration improves the efficiency of biogas production from food waste. The discovery that Proteobacteria dominate microbial communities in aerated food waste opens up opportunities to manipulate extracellular enzyme production through gene expression mechanisms common among Proteobacteria such as quorum sensing.

Gut microbes form a complex and dynamic symbiotic relationship with their host. However, the microbial response during the early stages following host death remains largely uncharacterized. In this study, we employed a mouse model to systematically characterize the postmortem response of the intestinal microbiota, and analyzed the dynamic changes in microbial composition during the early stages after death in both male and female mice (at 0, 0.5, 2, 6, 12, and 24 h postmortem). Our findings reveal that sex-dimorphic shifts in microbiome composition occur as early as 2 h postmortem. Male mice exhibited increased functional redundancy and delayed community restructuring, whereas female mice displayed earlier community shifts. These sex-specific patterns were accompanied by differences in metabolic pathway activity and biomarker taxa. Notably, the observed retention of regulatory capacity by intestinal microbes after host death offers a novel perspective on the conceptualization of death itself. We propose the term "ecological death" to describe the irreversible collapse of the host-associated microbial ecosystem following death, marking a critical transition in the functional and structural integrity of the intestinal microbiota.

The present study analysed the sensory quality and fungal community structure of three color types of high-temperature Daqu (HTD) produced in Qingzhou using electronic nose, electronic tongue, and high-throughput sequencing technology. The data were compared to the fungal data obtained from HTD produced in Xiangyang via the "partitioning around medoids" (PAM) clustering algorithm. PAM analysis indicated that all HTD samples from the two regions could be divided into two clusters. Cluster I samples were mainly characterized by Thermomyces, and cluster II samples were mainly characterized by Aspergillus and Thermoascus. Cooccurrence network analysis revealed that the correlations between fungal communities were stronger in the HTD dominated by Aspergillus and Thermoascus. The identification of key species and core operational taxonomic units demonstrated that the differences in the fungal community structure between the two HTD clusters were related to the abundance of certain fungal groups. Correlation analysis between fungal genera and sensory quality parameters showed that Thermomyces-dominated HTD had lower aftertaste-A, aftertaste-B, and organic sulfide and terpene content but a higher richness of flavor. Meanwhile, HTD dominated by Aspergillus and Thermoascus exhibited the opposite traits, and its sourness was relatively higher.