Publications

4560

ABSTRACT Background Data on feline hemotropic mycoplasmas is limited in Iran. Aim. The aim of this study was to investigate the infection rate of cats with this pathogen in Mashhad,Iran and evaluate its assosiation with cliniopathological changes. Materias & Methods Blood samples from 100 cats presenting at veterinary clinics were analysed for Mycoplasma haemofelis (Mhf) and Candidatus Mycoplasma haemominutum (CMhm). Samples were screened for hemotropic mycoplasmas using microscopic examination and conventional polymerase chain reaction (PCR). Samples were also subjected to haematological and biochemical analysis. Results Microscopic examination detected hemotropic mycoplasmas in 65% of samples, whereas PCR identified a 23% infection rate, with 65.21% ( n  = 15) positive for CMhm and 34.78% ( n  = 8) for Mhf. The presence of Haemomycoplasma DNA was significantly associated with age, gender, breed and roaming status ( p  < 0.05). Infected cats exhibited significant alterations ( p  < 0.05) in haematocrit (Hct), red blood cell count (RBC), haemoglobin (HGB), white blood cell count (WBC), neutrophil counts, serum total protein (TP), globulin, phosphorus (Pi), aspartate aminotransferase (AST) levels and the albumin/globulin ratio (AGR). Conclusions Our study highlights a high prevalence of feline hemoplasmosis in northeastern Iran, with CMhm as the predominant species. Key risk factors included male gender, adult, outdoor access and domestic short hair (DSH) breed. Although infected cats showed consistent clinicopathologic changes, no differences were observed between Mhf and CMhm infections.

ABSTRACT Insect‐vectored pathogens pose a significant threat to global agriculture. The colonization efficiency of pathogens in vectors plays a central role in these pathosystems, yet studies of the factors that affect this aspect are limited. This study investigates the genetic and microbial symbiont factors influencing the susceptibility of Diaphorina citri to Candidatus Liberibacter asiaticus ( C Las), the pathogen causing citrus greening disease (huanglongbing). Through a microbiome Genome Wide Association Study (mGWAS) based on 16S amplicon sequencing and genomic resequencing of 120 D. citri individuals from six populations, we identified 79 SNPs significantly associated with the relative abundance of C Las within insects. Additionally, some of these SNPs were also associated with the relative abundance of Candidatus Profftella armature, a key endosymbiont of D. citri . SNPs in the regulatory region of gene Dcitr04g11610.1 led to its overexpression in C Las‐susceptible D. citri , and C Las infection further elevated its expression. Conversely, RNAi knockdown of Dcitr04g11610.1 reduced C Las infection rates and abundance, accompanied by increased abundance of Profftella . Phylogenetic analysis revealed Dcitr04g11610.1 ’s high homology to Major Facilitator Superfamily‐type transporter SLC18B1 proteins, suggesting a role in C Las polyamine utilization. These findings highlight the importance and potential interplay of insect genetics and symbiotic microbiota in insect‐vectored plant pathogen systems.

Sweet potato witches’ broom disease caused by phytoplasmas threatens crop productivity in Fujian, China. Here, we report a complete phytoplasma genome consisting of a single circular chromosome (680,179 bp with a G + C content of 29.44%) via the next-generation sequencing of sweet potato witches’ broom-infected samples. A total of 730 genes were predicted, and two 16S rRNAs were revealed to be identical to sequences in ‘ Candidatus Phytoplasma australasiaticum’. Following the latest guidelines for the description of phytoplasma species, we have named the strain ‘ Candidatus Phytoplasma australasiaticum’ SPWBPT2024. The genome contained 33 transporters, 35 putative effectors (including SAP11 and SAP54 with multiple copies), and 2 potential mobile units. Analyses of published peanut and sweet potato phytoplasma genomes revealed similarities between their effectors and the effectors in this phytoplasma genome. A motif analysis was performed to clarify the difference between the two SAP54 copies in the obtained phytoplasma genome, as well as the trends in conserved motifs in other strains. In addition, metabolic pathway-related genes in three genomes were examined, revealing deficiencies in the glycolysis and pyrimidine synthesis pathways. A pangenome analysis revealed that the phytoplasma genome is an open genome. To gain further insights into whole-cell metabolic processes, we reconstructed draft genome-scale metabolic models of the genome. This study provides valuable genomic insights into this phytoplasma, characterizing conserved and strain-specific SAP effectors, as well as distinct metabolic deficiencies that may help advance research to combat phytoplasma infections, including accurate diagnostics, vector transmission control, and antimicrobial interventions.

Abstract Magnetotactic bacteria form a highly diverse group of microorganisms, yet early exploration of their diversity was largely centered on the Pseudomonadota. More recently, metagenomic studies have revealed that magnetotaxis, a form of chemotaxis guided by Earth's magnetic field, is widespread in other deep-branching phyla for which little to no ecological or biological information is available beyond that inferred from their genomes. For most of them, the morphology, ultrastructure and magnetosome chain characteristics responsible for the magnetic guidance remain unknown. While screening extreme environments for novel magnetotactic species, we observed magnetotactic Bdellovibrionota in the anoxic and ferruginous sediments of the Fontaine Goyon spring (France). We characterized their cell morphology and ultrastructure using magnetic enrichment, a single-cell sorting approach, and high-resolution electron microscopy. Cells display the morphology typical of the few predatory bacteria described in this phylum, and biomineralize, on average, five irregularly faceted, bullet-shaped magnetite magnetosomes along the concave side of the cell. Metagenomic analysis of approximately one hundred cells revealed a potentially predatory and heterotrophic lifestyle adapted to low-O2 conditions. It also suggests a flexible respiratory metabolism under varying redox conditions, using iron as an alternative terminal electron acceptor. Exploring the diversity of Bdellovibrionota in public databases, we found 21 metagenome-assembled-genomes containing magnetosome genes. None of them harbor the canonical mamK actin-like gene implicated in aligning magnetosomes in described magnetotactic models. Affiliated to an undescribed class, we propose a classification scheme for the magnetotactic Bdellovibrionota species representing the class Bdellonasia class nov., for which no species had been formally described.

ABSTRACT The oil refinery (OR) consortium is a model methanogenic enrichment culture used to study anaerobic benzene degradation. Over half of the culture’s bacterial community consists of two closely related Desulfobacterota strains, designated ORM2a and ORM2b, whose mechanisms of benzene activation are unknown. Three proteomics data sets were integrated and analyzed using high-quality OR metagenomes and metagenome-assembled genomes (MAGs), including a complete circularized ORM2a MAG, to identify active metabolic pathways and proteins expressed during methanogenic benzene degradation. Among the proteins identified were Bam-like subunits of an ATP-independent benzoyl-CoA degradation pathway, as well as downstream β-oxidation proteins yielding acetate. The most abundant proteins identified mapped to two ORM2a gene clusters of unknown function. Homologous and syntenic gene clusters were identified in the MAGs of ORM2b and a sulfate-reducing Pelotomaculum that also degrades benzene, as well as in nine contigs assembled from hydrothermal vent metagenomes. Extensive homology and structural predictions suggest that the first cluster—termed the “Magic” gene cluster—encodes for enzymes catalyzing the chemically challenging activation of benzene and subsequent transformation steps yielding benzoyl-CoA. The second (“Nanopod”) gene cluster encodes a transmembrane complex that may facilitate benzene transport across the cell membrane. Phylogenomic analyses place ORM2a and ORM2b within a novel genus of strict anaerobes specialized for benzene degradation, which we propose naming “ Candidatus Anaerobenzenivorax.” IMPORTANCE Benzene is a widespread, persistent, and toxic pollutant that can accumulate in anoxic environments such as groundwater and sediments. Benzene can be metabolized in the absence of oxygen; however, despite decades of research, the biochemical mechanisms for benzene activation under anaerobic conditions remain unproven. This study provides strong genetic and proteomic evidence for a new suite of enzymes that initiate anaerobic benzene activation. These findings lay a foundation for future biochemical studies and expand our understanding of how microbes carry out difficult chemical reactions in the absence of oxygen.

A hydrogenotrophic methanogen, designated strain ACI-7 T , was isolated from an alkaline, saline wetland located in eastern Nebraska, USA. Cells were identified as non-motile rods (0.9–4.2 µm in length and 0.2–0.4 µm in diameter) that occurred singly, in chains, or as twisted chains and aggregates. Strain ACI-7 T utilized H 2 +CO 2 or formate as methanogenic substrates and required growth factors present in yeast extract for continuous cultivation. The strain grew at 20–45 °C (optimum, 40 °C), at pH 6.5–8.5 (optimum, pH 7.3) and with 0–2.5% NaCl (optimum, 0–1%). The genomic G+C content of ACI-7 T was 31.79 mol%. Phylogenetic analysis of the 16S rRNA gene sequence indicated strain ACI-7 T was affiliated with the genus Methanobacterium , most closely related to Methanobacterium oryzae FPi T (97.1% sequence similarity) and Methanobacterium veterum MK4 T (96.9% sequence similarity). Overall genome relatedness indices for strain ACI-7 T compared to other Methanobacterium species ranged from 68.45 to 78.17% for average nucleotide identity and 18.9 to 25.7% for digital DNA–DNA hybridization. Morphological, physiological and genomic characteristics indicate that strain ACI-7 T represents a novel species, for which the name Methanobacterium nebraskense sp. nov. is proposed. The type strain is ACI-7 T (=DSM 118696 T =ATCC TSD-487 T ).