Alzheimer's disease (AD) is a prevalent neurodegenerative disorder. Despite substantial research efforts, our understanding of its pathogenesis remains incomplete, limiting the development of effective treatments and preventive strategies. The potential role of microbial pathogens in AD etiology has gained increasing attention. Various human microbial pathogens have been identified in the brains of AD patients, leading to the pathogen hypothesis, which posits that these microorganisms may disrupt the brain's immune regulation and homeostasis. In this study, we examine the effects of proteins from three pathogens, Borrelia burgdorferi, HSV-1, and Porphyromonas gingivalis, on the aggregation of antimicrobial peptide amyloid-β (Aβ). Three of the four studied proteins were found to attenuate the aggregation of Aβ42 by interacting with its soluble form and inhibiting primary and secondary pathways. These in vitro findings were further supported by experiments using mature neurons derived from human pluripotent stem cells, which showed an increased accumulation of amyloid precursor protein (APP) aggregates upon infection with HSV-1 or exposure to the OspA surface protein from B. burgdorferi. Together, our results provide mechanistic insights into how pathogen-associated proteins modulate Aβ42 aggregation, contributing to an understanding of their potential role in AD pathogenesis.

• Keywords
• Alzheimer’s disease, amyloid-β, amyloids, neuroinflammation, pathogen, virus,
• MeSH
• Alzheimer Disease * metabolism   microbiology   MeSH
• Amyloid beta-Peptides * metabolism   MeSH
• Amyloid beta-Protein Precursor metabolism   MeSH
• Bacterial Proteins * metabolism   pharmacology   MeSH
• Borrelia burgdorferi metabolism   MeSH
• Humans MeSH
• Herpesvirus 1, Human metabolism   MeSH
• Neurons metabolism   drug effects   MeSH
• Peptide Fragments * metabolism   MeSH
• Porphyromonas gingivalis metabolism   MeSH
• Check Tag
• Humans MeSH
• Publication type
• Journal Article MeSH
• Names of Substances
• amyloid beta-protein (1-42) MeSH Browser
• Amyloid beta-Peptides * MeSH
• Amyloid beta-Protein Precursor MeSH
• Bacterial Proteins * MeSH
• Peptide Fragments * MeSH

UNLABELLED: The intracellular parasite Cardinium influences the bacterial microbiome composition of arthropod hosts; however, the mechanisms involved remain poorly understood. We sought to evaluate the interactions between Cardinium (cTPut) and SOL in Tyrophagus putrescentiae cultures based on relative abundance and gene expression data. First, we assembled the genome of Candidatus Krakonobacterium acarorum (formerly the Soliltalea-like symbiont SOL), a novel lineage of the Bacteroidota symbiont of mites. The assemblage SOL genome (1.2 Mb) contained complete pathways for the biosynthesis of lipoic acids, pantothenate, and menaquinone from futalosine. SOL is considered a facultative inhabitant (with prevalences ranging from 36% to 80% among individuals) of the gut (from 102 to 104 copies/mite) that is not detected in eggs, suggesting an extracellular location in the gut of mites. Second, gene expression was analyzed in SOL-inhabited cultures, including two cultures with cTPut and two cultures without cTPut. Correlation-based evidence for competition between cTPut and SOL was found mainly in the expression of transporter proteins. The presence of cTPut decreased interactions between SOL and the mite host; however, SOL is under greater control by mites in the presence of cTPut than in the absence of cTPut. Mite KEGG gene expression levels in the peroxisome, autophagy, sphingolipid, apoptosis, PI3K-Akt, and lysozyme pathways were more strongly correlated with SOL gene expression in cultures without cTPut than in those with cTPut. In contrast, mite KEGG gene expression levels in the proteasome, NF-κB, TNF, calcium, and Rap1 signaling pathways were more strongly correlated with SOL in the presence of cTPut. The explanation for these results is that cTPut mostly interacts with the mite host, resulting in changes in the host's immunity-related/regulatory pathways, indirectly affecting the symbiont SOL. IMPORTANCE: Here, we describe the novel Bacteroidetes symbiont (SOL) of mites. The analysis of gene expression in meta-transcriptomic samples from cultures with and without the intracellular parasite Cardinium revealed the effect of Cardinium on SOL as a model facultative symbiont of mites. Our findings suggest that there is competition between these two symbionts for nutrients. In addition, Cardinium can influence other bacterial symbionts via mite host immunity-related and regulatory pathways. Tyrophagus putrescentiae is a cosmopolitan pest mite that contaminates the home environment, including stored food and feed, with allergens. The interactions between intracellular bacteria and other members of the microbiome influence host physiology and indirectly affect allergen production.

• Keywords
• Bacteroidetes, Bacteroidota, Cardinium, gene expression, interaction, mite, symbionts,
• MeSH
• Acaridae * microbiology   MeSH
• Bacteroidetes * genetics   physiology   classification   MeSH
• Phylogeny MeSH
• Genome, Bacterial MeSH
• Mites * microbiology   MeSH
• Gene Expression Profiling MeSH
• Symbiosis * MeSH
• Animals MeSH
• Check Tag
• Animals MeSH
• Publication type
• Journal Article MeSH

Type 1 diabetes (T1D) is caused by autoimmune destruction of pancreatic β-cells. The insulin B-chain 9-23 (insB9-23) peptide is a critical epitope in triggering T1D. In our previous study, we showed that Parabacteroides distasonis, a human gut commensal, contains an insB9-23 mimic in its hprt protein (residues 4-18). This mimic (hprt4-18) peptide activates insB9-23-specific T cells, and P. distasonis colonization enhanced diabetes in NOD mice. However, the impact of the P. distasonis colonization on inflammation, gut microbiome, intestinal immune cells, gut permeability, cytokine, and serum metabolome profiles remained unknown. Here, we investigated these effects using specific pathogen-free (SPF) and germ-free (GF) female NOD mice. P. distasonis colonization minimally impacted gut microbiome composition, altering only 28 ASVs. In P. distasonis-colonized mice, there was a reduction in T-helper, T-effector, and B-cell populations in the intraepithelial lymphocytes, indicating a potential decrease in immune activation. Furthermore, P. distasonis colonization did not alter serum metabolome and circulating cytokine profiles (except for a decrease in IL-15) and gut permeability gene expressions. P. distasonis colonization in GF NOD mice induced severe insulitis without affecting gut permeability. Interestingly, mice gavaged with heat-inactivated (HI) P. distasonis did not affect insulitis scores or immune cell composition. These findings support our hypothesis that P. distasonis functions as a gut commensal, exerting no effect on the gut microbiome, metabolome, gut permeability, intestinal immune cell composition, or nonspecific immune activation. Instead, P. distasonis appears to trigger an insB9-23-specific immune response, potentially accelerating T1D onset in NOD mice through molecular mimicry.

• Keywords
• Parabacteroides distasonis, autoimmunity, microbiome, molecular mimicry, type 1 diabetes,
• MeSH
• Bacteroidetes * physiology   MeSH
• Cytokines metabolism   MeSH
• Diabetes Mellitus, Type 1 * immunology   microbiology   metabolism   MeSH
• Metabolome * MeSH
• Mice, Inbred NOD MeSH
• Mice MeSH
• Gastrointestinal Microbiome * immunology   MeSH
• Animals MeSH
• Check Tag
• Mice MeSH
• Female MeSH
• Animals MeSH
• Publication type
• Journal Article MeSH
• Names of Substances
• Cytokines MeSH

Capnocytophaga spp. are typical members of the commensal microflora of the oral cavity. However, C. canimorsus can also be a dangerous pathogen, often causing fatal systemic infections, usually from contact with the saliva of dogs or cats. The article discusses the clinical significance of zoonotic infections with this bacterium as well as its natural occurrence, pathogenic adaptation, and the current problem of antimicrobial resistance. Keywords: Capnocytophaga spp., zoonosis, bite wound infection, oral microflora.

• MeSH
• Anti-Bacterial Agents pharmacology   therapeutic use   MeSH
• Drug Resistance, Bacterial MeSH
• Capnocytophaga * drug effects   isolation & purification   pathogenicity   MeSH
• Gram-Negative Bacterial Infections * drug therapy   microbiology   mortality   transmission   MeSH
• Cats * microbiology   MeSH
• Bites and Stings * complications   drug therapy   microbiology   MeSH
• Humans MeSH
• Microbiota physiology   MeSH
• Dogs * microbiology   MeSH
• Symbiosis physiology   MeSH
• Mouth * microbiology   MeSH
• Zoonoses * drug therapy   microbiology   mortality   transmission   MeSH
• Animals MeSH
• Check Tag
• Cats * microbiology   MeSH
• Humans MeSH
• Dogs * microbiology   MeSH
• Animals MeSH
• Publication type
• English Abstract MeSH
• Journal Article MeSH
• Review MeSH
• Names of Substances
• Anti-Bacterial Agents MeSH

UNLABELLED: We investigated the tripartite interactions between two intracellular bacterial symbionts, Cardinium and Wolbachia in Tyrophagus putrescentiae. Cultures of Tyrophagus putrescentiae are typically single-infected by one intracellular symbiont. However, co-infection can be experimentally induced by mixing single-infected cultures, resulting in 10% of mite individuals being double-infected (Cardinium + Wolbachia) and a corresponding reduction in host fitness. Here, we assembled the genomes of Cardinium and Wolbachia and analyzed their gene expression in parental single-infected and mixed mite cultures using population-level samples (ranging from 7,500 to 10,000 mites). Wolbachia interacts more extensively with its mite host than Cardinium in single-infected cultures. However, in mixed cultures, (i) Wolbachia exhibited reduced regulation of the host compared with Cardinium; (ii) the gene expression profile of Cardinium shifted, increasing its interactions with the host, whereas the gene expression profile of Wolbachia remained unchanged; and (iii) Wolbachia genes exhibited a loss of interactions with mite gene expression, as indicated by reduced correlations (for example with host MAPK, endocytosis, and calcium signaling pathways). The experiments show that at the mite population level, symbiont infection disrupts gene expression interaction between the two symbionts and their host in different ways. Wolbachia was more influenced by Cardinium gene expression than vice versa. Cardinium can inhibit the growth of Wolbachia by disrupting its interaction with the host, leading to a loss of Wolbachia's influence on mite immune and regulatory pathways. The reasons for responses are due to co-infection or the reduced frequency of Wolbachia single-infected individuals due to the analyses of population-level samples. IMPORTANCE: We found that Cardinium disrupts the interaction between Wolbachia and mite host. In Wolbachia single-infected cultures, strong correlations exist between symbiont and host gene expressions. Interestingly, although Cardinium can also interact with the host, this interaction appears weaker compared with Wolbachia in single-infected cultures. These results suggest that both symbionts affect mite host gene expression, particularly in immune and regulatory pathways. In mixed samples, Cardinium appears to outcompete Wolbachia by disrupting its host interaction. It indicates competition between these two intracellular symbionts in mite populations. Wolbachia belongs to a mite-specific supergroup Q, distinct from the more commonly studied Wolbachia supergroups. As these mite-specific bacteria exhibit pathogen-blocking effects, our findings may have relevance for other systems, such as ticks and tick-borne diseases. The study sheds light on intracellular symbiont interaction within a novel mite-symbiont model.

• Keywords
• Cardinium, Wolbachia, gene expression, genome, interaction, mite,
• MeSH
• Bacteroidetes * physiology   genetics   MeSH
• Mites * microbiology   MeSH
• Symbiosis MeSH
• Wolbachia * genetics   physiology   MeSH
• Animals MeSH
• Check Tag
• Animals MeSH
• Publication type
• Journal Article MeSH

We examined host and bacterial gene expression profiles in the stored product mite Tyrophagus putrescentiae co-infected with Wolbachia (wTPut) and Cardinium (cTPut) while varying the presence of the Erwiniaceae symbiont (SLS). SLS, a novel symbiont in the family Erwiniaceae, with a genome size of 1.7 Mb, is found in 16% of mite species in infected cultures. In addition, SLS was detected in mite feces but not in their eggs. Although Wolbachia expression remained unchanged, the presence or absence of SLS significantly affected Cardinium expression. It indicated that the effect of Wolbachia on SLS was neutral. In SLS-positive samples, Cardinium exhibited 29 upregulated and 48 downregulated genes compared to SLS-negative samples. Furthermore, Cardinium gene expression strongly correlated with mite KEGG gene expression in SLS-positive samples. Positive Spearman's correlations between Cardinium gene expression and mite KEGG immune and regulatory pathways were doubled in SLS-positive compared to SLS-negative samples. The diversity of expressed genes in the mite host decreased in the presence of SLS. Cardinium had more interacting genes to mite host in SLS-positive samples than without SLS. Transposases are the most affected Cardinium genes, showing upregulation in the presence of SLS. Correlation analyses revealed interactions between Cardinium and SLS via mite immune and regulatory pathways, including lysosome, ubiquitin-mediated proteolysis, PIK3_Akt, and cGMP-PKG. The results showed that Cardinium indirectly affects the gut symbionts of mites.IMPORTANCEThis study introduces a new model to analyze interactions between intracellular bacterial symbionts, gut bacterial symbionts, and their mite hosts. Using gene expression correlations, we investigated how the intracellular Cardinium responds to the novel Erwiniaceae gut symbiont in the mold mite Tyrophagus putrescentiae. The data showed that both mite and Cardinium gene expression are different in the samples with and without Erwiniaceae symbionts. In the presence of Erwiniaceae symbionts, Cardinium increased the interaction with the mite host in terms of changes in gene expression. The mite immune and regulatory pathway gene expression is differently correlated to Cardinium genes in relation to Erwiniaceae symbionts. As a well-known producer of allergens, T. putrescentiae physiology and thus its allergen production are influenced by both symbionts, potentially affecting the release of allergens into human environments.

• Keywords
• Cardinium, Erwiniaceae, Sodalis, Tyrophagus putrescentiae, Wolbachia, allergens, bacterial symbionts, gene expression, stored product mite,
• MeSH
• Acaridae * microbiology   MeSH
• Bacteroidetes * genetics   physiology   MeSH
• Gene Expression Regulation, Bacterial * MeSH
• Mites * microbiology   MeSH
• Gastrointestinal Microbiome * MeSH
• Symbiosis * MeSH
• Wolbachia genetics   physiology   MeSH
• Animals MeSH
• Check Tag
• Animals MeSH
• Publication type
• Journal Article MeSH

A novel Gram-stain-negative, strictly aerobic, rod-shaped, light-yellow-pigmented, and chemo-organoheterotrophic bacterium, designated DF-77T, was isolated from dense mats of filamentous algae collected in March 2004 at Okinawa in Japan. The microorganism grew at 0-2.0% NaCl concentrations (w/v), pH 6.0-9.0, and 20-30 °C. The 16S rRNA gene sequence-based phylogenetic tree demonstrated that the strain DF-77T is a novel member of the family Flavobacteriaceae and was greatly related to Flagellimonas nanhaiensis SM1704T with sequence similarity of 95.5%. The main fatty acids were iso-C15:1 G, iso-C15:0, and iso-C17:0 3-OH, and the only isoprenoid quinone was menaquinone-6. The dominant polar lipids were phosphatidylethanolamine, two unidentified aminolipids, an unidentified phosphoaminolipid, and four unidentified lipids. The genome size of strain DF-77T was 3.60 Mbp with a DNA G + C content of 47.5%. The average nucleotide identity (ANI) value between the genomes of strain DF-77T and its closely related species was 69.8-70.7%. The digital DNA - DNA hybridization (dDDH) value of strain DF-77T with the strain of F. nanhaiensis SM1704T was 16.8%. The genome of the strain DF-77T revealed that it encoded several genes involved in bio-macromolecule degradation, indicating a high potential for producing industrially useful enzymes. Consequently, the strain is described as a new species in the genus Flagellimonas, for which the name Flagellimonas algarum sp. nov., is proposed with the type strain DF-77T (= KCTC 72791T = NBRC 114251T).

• Keywords
• Flagellimonas algarum, Flavobacteriaceae, Polyphasic analysis,
• MeSH
• DNA, Bacterial genetics   chemistry   MeSH
• Flavobacteriaceae * classification   isolation & purification   genetics   MeSH
• Phospholipids analysis   MeSH
• Phylogeny MeSH
• Genome, Bacterial MeSH
• Nucleic Acid Hybridization MeSH
• Fatty Acids analysis   MeSH
• RNA, Ribosomal, 16S genetics   MeSH
• Sequence Analysis, DNA MeSH
• Bacterial Typing Techniques MeSH
• Vitamin K 2 analysis   analogs & derivatives   MeSH
• Base Composition MeSH
• Publication type
• Journal Article MeSH
• Geographicals
• Japan MeSH
• Names of Substances
• DNA, Bacterial MeSH
• Phospholipids MeSH
• Fatty Acids MeSH
• RNA, Ribosomal, 16S MeSH
• Vitamin K 2 MeSH

The gut microbiota influences the reactivity of the immune system, and Parabacteroides distasonis has emerged as an anti-inflammatory commensal. Here, we investigated whether its lysate could prevent severe forms of neuroinflammation in experimental autoimmune encephalomyelitis (EAE) in mice and how this preventive strategy affects the gut microbiota and immune response. Lysate of anaerobically cultured P. distasonis (Pd lysate) was orally administered to C57BL/6 mice in four weekly doses. One week later, EAE was induced and disease severity was assessed three weeks after induction. Fecal microbiota changes in both vehicle- and Pd lysate-treated animals was analyzed by 16S V3-V4 amplicon sequencing and qPCR, antimicrobial peptide expression in the intestinal mucosa was measured by qPCR, and immune cell composition in the mesenteric and inguinal lymph nodes was measured by multicolor flow cytometry. Pd lysate significantly delayed the development of EAE and reduced its severity when administered prior to disease induction. EAE induction was the main factor in altering the gut microbiota, decreasing the abundance of lactobacilli and segmented filamentous bacteria. Pd lysate significantly increased the intestinal abundance of the genera Anaerostipes, Parabacteroides and Prevotella, and altered the expression of antimicrobial peptides in the intestinal mucosa. It significantly increased the frequency of regulatory T cells, induced an anti-inflammatory milieu in mesenteric lymph nodes, and reduced the activation of T cells at the priming site. Pd lysate prevents severe forms of EAE by triggering a T regulatory response and modulating T cell priming to autoantigens. Pd lysate could thus be a future modulator of neuroinflammation that increases the resistance to multiple sclerosis.

• Keywords
• Parabacteroides distasonis, experimental autoimmune encephalomyelitis, inflammation, microbiota, multiple sclerosis, regulatory T cells,
• MeSH
• Bacteroidetes immunology   MeSH
• Encephalomyelitis, Autoimmune, Experimental * immunology   prevention & control   MeSH
• Mice, Inbred C57BL * MeSH
• Mice MeSH
• Gastrointestinal Microbiome * immunology   MeSH
• Intestinal Mucosa immunology   microbiology   metabolism   MeSH
• T-Lymphocytes immunology   metabolism   MeSH
• Animals MeSH
• Check Tag
• Mice MeSH
• Female MeSH
• Animals MeSH
• Publication type
• Journal Article MeSH

A novel β-galactosidase gene (PbBgal35A) from Pedobacter sp. CAUYN2 was cloned and expressed in Escherichia coli. The gene had an open reading frame of 1917 bp, encoding 638 amino acids with a predicted molecular mass of 62.3 kDa. The deduced amino acid sequence of the gene shared the highest identity of 41% with a glycoside hydrolase family 35 β-galactosidase from Xanthomonas campestris pv. campestris (AAP86763.1). The recombinant β-galactosidase (PbBgal35A) was purified to homogeneity with a specific activity of 65.9 U/mg. PbBgal35A was optimally active at pH 5.0 and 50 °C, respectively, and it was stable within pH 4.5‒7.0 and up to 45 °C. PbBgal35A efficiently synthesized galacto-oligosaccharides from lactose with a conversion ratio of 32% (w/w) and fructosyl-galacto-oligosaccharides from lactulose with a conversion ratio of 21.9% (w/w). Moreover, the enzyme catalyzed the synthesis of galacto-oligosaccharides from low-content lactose in fresh milk, and the GOS conversion ratios of 17.1% (w/w) and 7.8% (w/w) were obtained when the reactions were performed at 45 and 4 °C, respectively. These properties make PbBgal35A an ideal candidate for commercial use in the manufacturing of GOS-enriched dairy products.

• Keywords
• Pedobacter sp., Galacto-oligosaccharides, Hydrolysis, Synthesis, β-Galactosidase,
• MeSH
• Bacterial Proteins genetics   metabolism   chemistry   MeSH
• beta-Galactosidase * genetics   metabolism   chemistry   isolation & purification   MeSH
• Escherichia coli genetics   metabolism   MeSH
• Gene Expression MeSH
• Glycosylation MeSH
• Cloning, Molecular * MeSH
• Hydrogen-Ion Concentration MeSH
• Lactose * metabolism   MeSH
• Milk microbiology   MeSH
• Molecular Weight MeSH
• Oligosaccharides metabolism   MeSH
• Pedobacter * enzymology   genetics   MeSH
• Recombinant Proteins genetics   metabolism   chemistry   isolation & purification   MeSH
• Amino Acid Sequence MeSH
• Enzyme Stability * MeSH
• Substrate Specificity MeSH
• Temperature MeSH
• Publication type
• Journal Article MeSH
• Names of Substances
• Bacterial Proteins MeSH
• beta-Galactosidase * MeSH
• Lactose * MeSH
• Oligosaccharides MeSH
• Recombinant Proteins MeSH

BACKGROUND: The salmonid pathogen Flavobacterium psychrophilum poses a significant economic threat to global aquaculture, yet our understanding of its genetic and phenotypic diversity remains incomplete across much of its geographic range. In this study, we characterise the genetic and phenotypic diversity of 70 isolates collected from rainbow trout (Oncorhynchus mykiss) and brown trout (Salmo trutta m. fario) from fish farms in the Czech Republic between 2012 and 2019 to compare their genomic content with all draft or complete genomes present in the NCBI database (n = 187). RESULTS: The Czech isolates underwent comprehensive evaluation, including multiplex PCR-based serotyping, genetic analysis, antimicrobial resistance testing, and assessment of selected virulence factors. Multiplex PCR serotyping revealed 43 isolates as Type 1, 23 as Type 2, with sporadic cases of Types 3 and 4. Multi-locus sequence typing unveiled 12 sequence types (ST), including seven newly described ones. Notably, 24 isolates were identified as ST329, a novel sequence type, while 22 were classified as the globally-distributed ST2. Phylogenetic analysis demonstrated clonal distribution of ST329 in the Czech Republic, with these isolates lacking a phage sequence in their genomes. Antimicrobial susceptibility testing revealed a high proportion of isolates classified as non-wild type with reduced susceptibility to oxolinic acid, oxytetracycline, flumequine, and enrofloxacin, while most isolates were classified as wild type for florfenicol, sulfamethoxazole-trimethoprim, and erythromycin. However, 31 isolates classified as wild type for florfenicol exhibited minimum inhibitory concentrations at the susceptibility breakpoint. CONCLUSION: The prevalence of the Czech F. psychrophilum serotypes has evolved over time, likely influenced by the introduction of new isolates through international trade. Thus, it is crucial to monitor F. psychrophilum clones within and across countries using advanced methods such as MLST, serotyping, and genome sequencing. Given the open nature of the pan-genome, further sequencing of strains promises exciting discoveries in F. psychrophilum genomics.

• Keywords
• Flavobacterium psychrophilum, Antimicrobial susceptibility, Aquaculture, Farmed rainbow-trout, Genetic diversity, Serotypes,
• MeSH
• Anti-Bacterial Agents pharmacology   MeSH
• Drug Resistance, Bacterial genetics   MeSH
• Virulence Factors genetics   MeSH
• Phenotype MeSH
• Flavobacterium * genetics   isolation & purification   classification   drug effects   MeSH
• Phylogeny * MeSH
• Genetic Variation * MeSH
• Genome, Bacterial genetics   MeSH
• Flavobacteriaceae Infections * microbiology   veterinary   MeSH
• Microbial Sensitivity Tests MeSH
• Multilocus Sequence Typing * MeSH
• Fish Diseases * microbiology   MeSH
• Oncorhynchus mykiss * microbiology   MeSH
• Trout microbiology   MeSH
• Serotyping MeSH
• Aquaculture MeSH
• Animals MeSH
• Check Tag
• Animals MeSH
• Publication type
• Journal Article MeSH
• Geographicals
• Czech Republic MeSH
• Names of Substances
• Anti-Bacterial Agents MeSH
• Virulence Factors MeSH