Fems Microbiology Letters最新文献

Plasmids are obligate genetic parasites that significantly influence bacterial host adaptation, ecology, and clinically relevant traits such as antibiotic resistance. They persist within host populations primarily through self-maintenance mechanisms, most notably Toxin-Antitoxin (TA) systems, which are autoregulated poison-antidote operons mediating genomic conflict. Plasmid-encoded TAs act as "addiction modules," promoting plasmid stability via post-segregational killing of daughter cells that fail to inherit the plasmid. However, the widespread and abundant presence of TAs on bacterial chromosomes remains an evolutionary puzzle. We conducted comprehensive bioinformatics analyses of 11 000 bacterial chromosomes and 1300 plasmids, focusing on Type II TAs in Escherichia and Shigella species, to elucidate their prevalence, distribution, and ecological significance. Our results reveal distinct horizontal gene transfer patterns and strongly support the antiaddiction hypothesis, which posits that chromosomal TAs protect host cells by neutralizing TA-plasmid addiction effects. This neutralization allows for plasmid loss without the toxin-mediated lethal consequences, resulting in a pattern of mutual exclusivity between identical chromosomal and plasmid TAs. This study reinforces the view that chromosomal Type II TA systems play a significant role in counteracting addiction processes within bacterial chromosomes.

Glyceraldehyde-3-phosphate dehydrogenase (GAPDH) is classically recognized as a glycolytic enzyme that catalyzes the conversion of glyceraldehyde 3-phosphate into D-glyceryl 1,3-bisphosphate. However, it also exhibits "moonlighting" functions, serving roles unrelated to metabolism. Notably, this multifunctional protein, which lacks a conventional membrane anchor, is present on the surface of many prokaryotic and eukaryotic cells. In this study, we demonstrate that Leptospira interrogans GAPDH (LiGAPDH) is surface-exposed and interacts with plasminogen. In the presence of the exogenous activator uPA, plasminogen is converted into its active form, plasmin. The LiGAPDH-plasmin complex can degrade fibrinogen (α and β chains) and the 75-kDa form of vitronectin over time. Interestingly, plasmin, when bound to LiGAPDH, completely degrades the C5 α-chain but does not affect C3b. The functional characterization of moonlighting proteins and the identification of host molecules they interact with may offer insights for understanding the mechanisms of invasion, dissemination, and immune evasion employed by pathogenic leptospires.

Sheep and sheep products play a notable role in Albanian culture and economy, particularly in rural regions. This sector is defined by small-scale activities and often faces challenges linked to safety and productivity. These issues necessitate the development of reforms to protect public health, boost productivity, and comply with regulatory requirements. Escherichia coli is a frequent ovine commensal, with an association with pathotypes like Shiga Toxin-encoding E. coli. The relationship between ovine bacteria and antibiotic resistance further remains poorly characterized. In this study, E. coli isolates from sheep across Albania were sequenced using Oxford Nanopore Technologies™ and characterized in silico for serotype, virulence, resistance genes, and phylogenetic relationships as isolates were compared to a global collection of animal and environmentally associated genomes. Isolates exhibited diverse serotypes and a conserved resistome comprising four genes, including EC-type β-lactamases. Four isolates were Shiga toxin-positive (stx1c predominant). Phylogenetic analyses revealed high similarity with European ovine E. coli, indicating regional relatedness and potential for resistance gene dissemination. This work provides the first genomic insight into ovine E. coli in Albania and highlights their potential role in antimicrobial resistance dynamics within livestock systems. These findings are crucial to understand for the development of Albanian agricultural practices.

The scientific and technological change at the recent speed and scale, and the vast amount of information available at everyone's fingertips, can be overwhelming. Thus, scientists and educators need to support everyone in becoming and being able to judge scientific expertise and the credibility of a source and the information provided; and need to facilitate developing or strengthening trust in science. Papers from around the globe, addressing current educational approaches that drive the development of science literacy, were published in the FEMS Microbiology Letters virtual Thematic Issue 'Learning together for our future' in October 2025. The paper's themes of timely education practice range from public engagement with microbiology, active and authentic learning that prepares for professional and civic contributions, to citizen science and service learning. Its content is reviewed and contextualized here to facilitate discussions within the professional community. Crucially, we need to offer and create inclusive opportunities for learning and developing science literacy, so we can truly learn together for our future.

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.

The microbial communities in anaerobic ammonium oxidation (anammox) bioreactors have been extensively studied to unveil their diversity and roles in nitrogen removal. Yet, the viruses infecting the key functional microorganisms in these systems remain unexplored. Here, we utilize genome-resolved metagenomics to systematically assess viral diversity, functions and interaction with microbial hosts in granular sludges of different sizes from three laboratory-scale (LS) and full-scale (FS) anammox reactors. Analysis of the 190 microbial genomes recovered through bulk metagenomics revealed the predominance (FS 29%-54% and LS 31%-45%) of anammox species exclusively from the Brocadiae in all sludges examined. Viral metagenomics identified 5210 candidate viral species, 61.1∼97.3% of which were novel. Members of six genera from the Caudovirales order constitute the majority of the taxonomically assigned viral species. Between-group variance analysis revealed that both environment (reactor type) and granule size had a significant influence on the metabolic potential of viruses. In silico predictions showed that many of the important functional microbes were frequent targets of previously unrecognized viruses, including six viral populations infecting the anammox bacteria. Our results suggest that viruses actively infect microbial hosts and thus may have a major impact on the microbial metabolic processes and biogeochemical cycling in the anammox reactors.

Bradyrhizobium, the largest rhizobial genus, is characterized by a variety of exopolysaccharide (EPS) components, such as penta- and tetrasaccharides, depending on the species. However, several genes involved in EPS synthesis remain unknown. In this study, we investigated whether 186 Bradyrhizobium strains possess homologous genes in the EPS cluster I, which is responsible for the synthesis of a pentasaccharide EPS by B. diazoefficiens USDA110. The absence of homologous genes in the B. elkanii and Photosynthetic Bradyrhizobium supergroups, in contrast to the B. japonicum supergroup, suggests that these lineages may utilize distinct and uncharacterized genes involved in tetrasaccharide EPS biosynthesis.

Methanogens rely on compatible solutes to withstand osmotic stress, yet their responses to high ammonium concentrations, common in biogas digesters, remain poorly understood. In this study, intracellular osmolyte accumulation was examined in four Methanoculleus bourgensis strains (MAB1, MAB2, MAB3, and BA1), isolated from high-ammonia biogas digesters, under progressive increase in concentrations of ammonium and sodium chloride. Their responses were compared with those of the type strain Methanoculleus bourgensis MS2T and the halophilic Methanoculleus submarinus Nankai-1T. All investigated strain grew to 12 g l-1 NH4+-N (0.3 mg l-1 NH3), and gradual adaptation increased ammonium/ammonia tolerance in some strains to 25 g l-1 NH4+-N. Whereas the reference strains accumulated glycine betaine under both ammonium and sodium chloride stress, the M. bourgensis strains from high ammonia biogas systems uniquely accumulated Nε-acetyl-β-lysine during increasing levels of ammonium chloride. This β-amino acid derivative is known as a NaCl-induced osmoprotectant in methanogens, but it´s association with high ammonium/ammonia levels in pure cultures has not previously been demonstrated. Our findings identify Nε-acetyl-β-lysine biosynthesis as a potential mechanism underpinning the exceptional ammonium/ammonia tolerance of M. bourgensis, a taxon frequently dominating methane production in high-ammonia biogas systems, while also revealing notable variation in this trait among its subspecies.

Trichoderma fungi are colonizers of plant substrates and rhizosphere and are valued for their antagonism against phytopathogens and ability to promote plant health. We investigated Trichoderma diversity in coffee-growing soils in Caranavi region of Yungas-La Paz, Bolivia, where high humidity and fungal diseases threaten yield, and evaluated their potential as biocontrol agents against coffee pathogens. A total of 440 Trichoderma were isolated from coffee rhizosphere, fallow lands, and forest ecosystems across an altitudinal gradient in Caranavi. DNA barcode analyses using ITS, rpb2, and tef1 loci identified only four species. However, 47 taxa comprising 344 isolates were ambiguous, and 41 isolates were previously unrecognised species. The diversity of Trichoderma spp. was significantly affected by ecosystem type and altitude, with more species isolated from coffee rhizosphere than fallow lands and forest ecosystems, and from lower altitudes than higher ones. Evaluation of 100 isolates against a native coffee wilt pathogen Fusarium oxysporum identified 70 potent antagonists, with 30 achieving 90-100% disease control. This is the first comprehensive study of Trichoderma diversity in Yungas, identifying indigenous Trichoderma for biocontrol applications against coffee diseases. It also emphasizes the need to refine the Trichoderma species concept and improve the taxonomic resolution within the genus.