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Microbiology Resource Announcements

American Society for Microbiology

Preprints posted in the last 90 days, ranked by how well they match Microbiology Resource Announcements's content profile, based on 25 papers previously published here. The average preprint has a 0.02% match score for this journal, so anything above that is already an above-average fit.

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Genome sequence of Bacillus paranthracis strain SCM10-01, isolated from the intestinal mucosa of a wild Synallaxis cabanisi collected in Peru.

Finkelstein, E.; Hird, S. M.

2026-08-12 genomics 10.64898/2026.08.12.744436 medRxiv
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We report the genome sequence of Bacillus paranthracis SCM10-01, isolated from a wild neotropical bird (Synallaxis cabanisi) collected in Peru. The assembly yielded one chromosome, three plasmids, and Bacillus phage SCM10. Genomic screening identified complete hemolysin BL, nonhemolytic enterotoxin operons, and cytotoxin K2, but no anthrax-associated toxin or capsule genes.

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Population Structure, Novel Sequence Types, and Antimicrobial Resistance in Vibrio parahaemolyticus and Vibrio vulnificus: A Whole Genome Sequencing Study of Clinical and Seafood Isolates in New Jersey

Schlitt, L.; Jeong, B.; Wu, F.-M.; Bodnar, L.; Panyi, A.; Bilinski, J.; Steinberg, M.; Lloyd, C.; Hutcheson, J.; Oyelade, A.; Carayannopoulos, M.; Kirn, T.; Nindo, F.

2026-08-06 public and global health 10.64898/2026.07.30.26359351 medRxiv
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Vibrio parahaemolyticus and Vibrio vulnificus are significant foodborne pathogens linked to seafood consumption and environmental exposure. Whole genome sequencing (WGS) was performed on Vibrio isolates collected from clinical cases and seafood sources throughout the state of New Jersey to elucidate genomic diversity, antimicrobial resistance (AMR) profiles. Sequences were included from isolates collected over eight years, from June 2016 to November 2024. This study identified 465 Vibrio sequences, 406 sequences from seafood sources and 59 sequences from clinical cases. Species-level taxonomic identification via Kraken2 classified 300 isolates as Vibrio parahaemolyticus and 165 as Vibrio vulnificus from whole genome assemblies. Multi-locus sequence typing (MLST) indicated a diverse population of isolates, with 169 known Vibrio sequence types (STs) identified. An additional 168 potential novel allelic profiles were identified, comprising 19.3% of V. parahaemolyticus sequences and 90.9% of V. vulnificus sequences. Novel sequence types were submitted to pubMLST for classification, resulting in the identification of 49 novel V. parahaemolyticus STs and 113 novel V. vulnificus STs. Three V. parahaemolyticus sequence types were identified in both clinical and environmental sequences. A single novel sequence type was identified in both clinical and environmental sequences of V. vulnificus. Analysis of antimicrobial resistance genes revealed the presence of the tetracycline resistance gene tet(34) in nearly all isolates. Beta-lactamase genes were detected in nearly all V. parahaemolyticus sequences but were absent from V. vulnificus, with gene profiles varying by sequence type. To the best of our knowledge, this study provides the first comprehensive WGS-based analysis of the genomic diversity and antimicrobial resistance profiles of Vibrio parahaemolyticus and Vibrio vulnificus isolates from clinical and seafood sources in New Jersey over an eight-year period, to support public health surveillance of these foodborne pathogens.

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The genome of the coral model sea anemone Exaiptasia diaphana (Aiptasia) strain F003

Doerr, M.; Sharaf, A.; Colin, L.; Schuster, K.; Bell, A.; Voolstra, C. R.

2026-08-28 genomics 10.64898/2026.08.25.747183 medRxiv
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We present a genome assembly of Aiptasia strain F003, a broadly used laboratory strain of the sea anemone and coral model organism Exaiptasia diaphana (Cnidaria; Anthozoa; Hexacorallia; Actiniaria; Aiptasiidae; Exaiptasia). The genome assembly spans 237.34 Mb across 12,480 contigs with a contig N50 of 76.47 kb (12,423 scaffolds with a scaffold N50 of 77.93 kb), including a single-contig mitochondrial genome with a length of 19.79 kb. The assembly is highly complete with a BUSCO completeness of 96.50% based on the metazoa dataset, including 94.80% single-copy, 1.70% duplicated, 1.70% fragmented, and 1.80% missing BUSCO genes. Genome annotation identified 29,589 protein-coding genes (including 2 pseudogenes) and a repeat content of 32.89%. The genome of the female Aiptasia strain F003 enhances the utility of a key cnidarian model organism by enabling comparisons among Aiptasia strains in studies of symbiosis, microbiomes, and thermal stress. It thereby strengthens the value of Aiptasia as a model for investigating the mechanisms underlying coral holobiont function, response, and resilience to environmental change.

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Peptonella octanoica gen. nov., sp. nov., a new medium-chain carboxylate-producing bacterium, and the reclassification of Eubacterium pyruvativorans as Peptonella pyruvativorans comb. nov.

Kumar Nallasamy, D.; Lindner, B. G.; Lawson, C. E.

2026-08-24 microbiology 10.64898/2026.08.23.746564 medRxiv
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A strictly anaerobic bacterial strain, F2T, was isolated from an anaerobic bioreactor fermenting source-separated organic waste. Cells of strain F2T are non-spore-forming, rod-shaped (1.5-2.5 x 0.27-0.33 m), and Gram-negative, although they possess a monoderm cell wall architecture. The strain grew at 37 degrees C within a pH range of 5 to 8 and produced short-, branched-, and medium-chain carboxylates as well as ammonium, H2 and CO2, with acetate and propanoate produced or consumed depending on fermentation conditions. The genome consists of a single 2.4 Mbp chromosome with a G+C content of 50.2% and 2,131 predicted genes. Phylogenetic analysis of the 16S rRNA gene against other isolates revealed that strain F2T is most similar to Eubacterium pyruvativorans I-6T (92.06% 16S rRNA identity). Based on further phenotypic, genomic, and phylogenetic analysis, strain F2T represents a novel genus and species within the family Anaerovoracaceae with the proposed name Peptonella octanoica gen. nov. sp. nov. The type strain is F2T (strain accession pending). As a member of this same genus-level clade, we propose reclassifying Eubacterium pyruvativorans as Peptonella pyruvativorans comb. nov. These findings disambiguate Peptonella spp. from the phylogenetically distant and phenotypically distinct Eubacterium limosum ATCC 8486T.

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Phylogenomic description of three novel species of the Microbulbifer genus, phylum Pseudomonadota, isolated from marine sponges and corals

Tang, Y.; Track, A.; Miller, N. A.; Mandelare-Ruiz, P.; Paul, V. J.; Konstantinidis, K. T.; Agarwal, V.

2026-06-11 microbiology 10.64898/2026.06.10.731415 medRxiv
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AO_SCPLOWBSTRACTC_SCPLOWUnderstudied bacterial genera present a dynamic phylogenetic landscape and opportunities for discovering new taxa as more strains are isolated and genomic data is added. Here, through phylogenomic analysis, we describe three novel species of the globally distributed cosmopolitan marine bacterial genus Microbulbifer. This genus is ubiquitous in saltwater microbiomes and is a validated source of biodegradation enzymes as well as high value small molecule natural products. Average nucleotide identity (ANI) to the closest known species, Microbulbifer variabilis ATCC 700307T, was less than 88.4% for all three novel species. Isolates of the three novel species, designated as PAAF003T (T = type strain), ZKSA006T, and SSSA003T were imaged to reveal their phormological characteristics. Based on phylogenetic data, strains PAAF003T, ZKSA006T, and SSSA003T represent three new species of the genus Microbulbifer, for which the names Microbulbifer maximicatervae sp. nov., Microbulbifer regidiadema sp. nov., and Microbulbifer mixtoriginis sp. nov. are proposed, respectively, under the SeqCode. We also reconstructed a robust phylogeny of available Microbulbifer genomes, which should faciliatate future isolation and strain description studies.

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Whole genome sequences and annotations of Japanese and French strains of Heterosigma akashiwo

Kondo, T.; Sakamoto, M.; Tokumaru, M.; Tanizawa, Y.; Nakamura, Y.; Toyoda, A.; Ueki, S.

2026-08-23 genomics 10.64898/2026.08.19.745619 medRxiv
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High-quality reference genomes provide an essential foundation for elucidating the molecular basis of organismal ecophysiology. Here, we sequenced and assembled chromosome-scale genomes of two Heterosigma akashiwo strains isolated from coastal waters of Japan and France. The assembly sizes were 1.18 Gb and 1.43 Gb for the Japanese and French strains, respectively. The scaffold N50 of the Japanese strain assembly was 66 Mb, whereas the one of the unscaffolded French strain assembly was 33 Mb. To our knowledge, these assemblies represent among the largest and most contiguous genome resources currently available for members of the Stramenopiles (Ochrophyta). Evidence-based gene prediction in the Japanese strain recovered approximately 90% of conserved stramenopile core genes, indicating a highly complete gene repertoire, and was complemented by extensive functional annotation. In the French strain, homology-based gene prediction recovered approximately 80% of conserved core genes. Comparative genome analysis revealed extensive synteny conservation between the two strains, although several putative duplication and translocation events were detected. These genomic resources provide a robust framework for investigating the molecular, cellular, and ecological mechanisms underlying the physiology, adaptation, and bloom-forming capacity of H. akashiwo.

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First outbreak of Lumpy Skin disease in Catalonia, Spain, 2025-2026

Obregon-Gutierrez, P.; Correa-Fiz, F.; Fonseca-Rodriguez, O.; Cortey, M.; Cobos, A.; Riera, C.; Soler, M.; Ribas, N.; Domenes, F.; Pailler-Garcia, L.; Domingo, M.; Majo, N.; Vidal, E.; Lorca-Oro, C.

2026-06-22 genomics 10.64898/2026.06.18.733166 medRxiv
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Lumpy skin disease (LSD) is an emerging cattle disease caused by lumpy skin disease virus (LSDV), with major impacts on the industry, being classified as a Category A disease. Although it was historically confined to Africa, LSD has expanded into the Middle East, Asia and Europe. Here, we report two LSDV genomes from the first outbreak detected in Catalonia, Spain, in October 2025. The genomes were assembled from high-throughput sequencing data generated from two homogenized skin nodules. Comparative phylogenetic analyses were performed using all available complete LSDV genomes and rpo30 gene sequences. These analyses placed the LSDV isolates detected in Catalonia within clade 1.2, closely related to the isolates recently reported in Sardinia, Italy. Our findings also support a connection between recent south-western Europe and central African strains, possibly through northern Africa, and highlight the need for more complete genomes to clarify the origin and connections among recent LSDV outbreaks.

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Detection and Genomic Characterization of Heartland and Bourbon Viruses in Amblyomma americanum ticks from Nebraska

Pella, Z.; Moody, J.; Rodriguez, S. A.; Chandler, S.; Smith, H.; Bartling, A. M.; Herzog, K. S.; Uhm, S. A.; Stein, S.; Iwen, P. C.; McCutchen, E. L.; Kenney, J. L.; Hamik, J.; Newman, B.; Fauver, J. R.

2026-08-10 public and global health 10.64898/2026.08.06.26359924 medRxiv
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Heartland virus (HRTV) and Bourbon virus (BRBV) are emerging tick-borne arboviruses transmitted by the lone star tick (Amblyomma americanum) that have caused dozens of cases of human disease in the United States, including multiple fatalities. Despite their significance, entomological, clinical, and molecular surveillance remains sparse, limiting our understanding of HRTV and BRBV distribution and risk. The Nebraska Department of Health and Human Services and the Nebraska Public Health Laboratory expanded tick-borne pathogen surveillance to include HRTV and BRBV in A. americanum ticks beginning in 2024. Here, we report the first detections of HRTV and BRBV in Nebraska and present a multi-segment phylogenetic analysis of complete virus genomes. Using a newly developed amplicon-based whole genome sequencing strategy, we generated complete HRTV genomes from three PCR-positive A. americanum pools collected in two counties in eastern Nebraska. Additionally, we generated a complete BRBV genome from a single PCR-positive A. americanum pool. A time-calibrated phylogenetic analysis of the L segment containing all publicly available HRTV sequences determined that the 3 genomes from Nebraska form a monophyletic cluster that initially diverged from viruses isolated from Missouri in the early 2000s, corresponding with the expansion of A. americanum into Nebraska. A phylogenetic analysis of BRBV segment 2 indicates that the genome from Nebraska sits on a long branch and likely diverged from other genomes sequenced in the early 2010s. Topological concordance across each segment suggests minimal occurrences of reassortment among the HRTV and BRBV genome sequences. These findings document the expansion of HRTV and BRBV to the western margin of the A. americanum range and demonstrate the utility of enhanced surveillance and whole genome sequencing for characterizing the spread of tick-borne arboviruses.

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Phylogenomics and comparative genomics of the genus Erwinia reveal taxonomic inconsistencies and evolutionary diversification

Maurya, N.; Dobhal, S.; Sundin, G. W.; Rodoni, B.; Stack, J. P.; Arif, M.

2026-08-11 genomics 10.64898/2026.08.06.743344 medRxiv
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The genus Erwinia comprises a diverse group of bacteria associated with plants, insects, and the environment, including several economically important phytopathogens. The genus has been revised taxonomically many times, yet a thorough and genome-wide assessment of its evolutionary relationships and genomic diversity has been lacking. In this research, we carried out an extensive phylogenomic and comparative genomic analyses of the genus Erwinia using 104 genomes including historically important strains. Genome-wide analyses integrating average nucleotide identity (ANI), digital DNA-DNA hybridization (dDDH), core-genome phylogenomics, pan-genome analysis, and comparative genomics resolved evolutionary relationships across the genus and identified multiple taxonomic inconsistencies. The pan-genome analysis revealed a relatively small core genome alongside an extensive accessory genome, underscoring the substantial genomic plasticity and ongoing diversification within the genus. The comparative analyses further showed pronounced lineage-specific variation in secretion systems, exopolysaccharide biosynthetic loci, flagellar gene clusters, genomic islands, prophages, and iron acquisition systems, suggesting that virulence-associated determinants have evolved through differential gene gain, loss, and conservation across distinct lineages, thereby facilitating host and ecological niche adaptation. This lineage-specific variation indicates that pathogenicity in the genus is not driven by a single conserved set of virulence determinants but instead reflects distinct combinations of virulence-associated genes. These findings refine the genomic framework of the genus Erwinia, provide evidence for taxonomic revision of several lineages, and improve our understanding of the evolutionary relationships, genomic diversification, and lineage-specific adaptations associated with host interactions and ecological specialization. Impact StatementThis study provides the first comprehensive genome-wide phylogenomic framework for the genus Erwinia, integrating taxonomy, pan-genome diversity, virulence-associated determinants, and mobile genetic elements across all 18 currently recognized species. Analyses resolve evolutionary relationships, uncover multiple taxonomic inconsistencies, identify previously unrecognized species-level lineages, including a putative novel Erwinia species PL328 isolated from Cornus florida (dogwood), and reveal lineage-specific genomic features. These findings establish a valuable genomic foundation for future studies of Erwinia evolution, taxonomy, and plant-microbe interactions. Data SummaryGenomes sequenced in this study were submitted to the NCBI database under the accession numbers: JCBCPT000000000

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Regional endemicity of toxigenic Vibrio parahaemolyticus lineages associated with foodborne illness in Australia

Lacey, J. A.; Hedges, C. E.; Watt, A. E.; Torok, V. A.; Jenkins, C.; Franklin, N.; Knight, D. R.; Fearnley, E.; Mercoulia, K.; Papanicolas, L. E.; Graham, R. M. A.; Leong, L. E.; Jennison, A. V.; Sintchenko, V.; Howden, B.; Sherry, N. L.; Turnbull, A.

2026-08-22 public and global health 10.64898/2026.08.19.26360778 medRxiv
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Gastrointestinal Vibrio parahaemolyticus infections, primarily associated with consumption of oysters, are emerging in Australia, where previously little was known about the disease and epidemiology. Following a multijurisdictional outbreak in 2021 and additional smaller outbreaks in subsequent years, an opportunistic whole genome sequencing study was undertaken to characterise human illness-causing strains in Australia. Through a multijurisdictional collaboration that bridged research, government, pathology service providers, aquaculture and clinicians, 676 V. parahaemolyticus genomes were contributed for analysis from human clinical, food, and environmental samples. We identified ST36, ST50 and ST417 as the dominant multi-locus sequence types causing gastrointestinal illness nationally. Phylogeographic contextualisation of Australian V. parahaemolyticus sequences within the global dataset indicates the Australian and New Zealand ST36 strain originated from a single point of introduction from the US Pacific-Northwest and is now circulating locally. In contrast, ST50 and ST417 appear to be endemic across Australia, with multiple lineages co-circulating. These findings establish a baseline for future outbreak investigations of V. parahaemolyticus in Australia and the consolidation of Australian data provides a critical platform for ongoing research, public health surveillance and risk mitigation.

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Complete mitochondrial genomes of Arizona West Nile virus vectors, Culex quinquefasciatus and Culex tarsalis

Barrand, Z. A.; Ridenour, C. L.; Erickson, D. E.; Rivas, A. N.; Schmidt, B. K.; Will, J.; Young, S. J.; Busser, N.; Townsend, J.; Enriquez, D.; Murphy, D.; Wong, S.; Keats, J.; Carvalho, S. T.; Attardo, G. M.; Barker, C. M.; Hepp, C. M.

2026-08-21 genomics 10.64898/2026.08.14.744795 medRxiv
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Here we report a newly developed method utilizing long-range PCR and long-read Pacific Biosciences HiFi sequencing that successfully obtained two full-length and annotated mitochondrial genomes from Culex quinquefasciatus Say, 1823 and Culex tarsalis Coquillett, 1896, both from Maricopa County, Arizona, USA. Given the substantial burden of West Nile virus in Maricopa County over the past decade, and that these vectors are primarily responsible for spillover to human populations in the county, it is critical to better understand their distribution over time and space. This study begins to approach this need by contributing a novel approach that has resulted in the first West Nile virus vector mitochondrial genomes from Arizona. Our circular Cx. quinquefasciatus mitogenome is 15,587 bp in length, making it the first USA-based mitogenome sequenced through the AT-rich control region. The Cx. tarsalis mitochondrial genome is 16,416 bp long, longer than recently published California-based CTarK1 and Texas-based PQ585801 mitogenomes. The increased length of the Cx. tarsalis mitogenome is a result of a 905 bp insertion in the AT-rich control region, not present in the species publicly available mitogenomes. A maximum likelihood-based phylogenetic reconstruction supports the species designation of these newly-sequenced mitogenomes. The newly developed methodology offers a unique approach to study medically-important vector species around the globe, providing a solution to study populations through pooled vector pathogen surveillance programs.

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The genome sequence of Seabra's wing-gland bat, Cistugo seabrae Thomas, 1912

Benda, P.; Uelze, L.; Brown, T. F.; Winkler, S.; Myers, E. W.; Pippel, M.; Eiseb, S. J.; Howard, A.; Pieri, M.

2026-08-05 genomics 10.64898/2026.07.30.741839 medRxiv
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We present a genome assembly from a female Cistugo seabrae (Seabras wing-gland bat; Chiroptera; Cistugidae). The genome sequence is 1.9 gigabases (Gb) in span. The majority of the assembly is scaffolded into 25 chromosomal pseudomolecules, with the XX chromosomes assembled. The assembly has a contig N50 of 51.9 Mb and a scaffold N50 of 91.4 Mb. Species taxonomyEukaryota; Metazoa; Chordata; Craniata; Vertebrata; Euteleostomi; Mammalia; Eutheria; Laurasiatheria; Chiroptera; Yangochiroptera; Vespertilionoidea; Cistugidae; Cistugo; Cistugo seabrae Thomas, 1912 (Teeling et al., 2005; Bickham et al., 2004; Lack et al., 2010).

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A chromosome-level genome of the franciscana dolphin, Pontoporia blainvillei

Canesin, L. E. D.; Aleixo, A.; Vidal, A.; Martins, A. B.; Farro, A. P. C.; Kolesnikovas, C. K. M.; Cordeiro, D. d. M.; Neuhaus, E. B.; Luna, F. O.; Araujo, F. A. A.; Nunes, G.; Cunha, H. A.; Mendes, I. S.; Mattos, J. S.; Albuquerque, L.; Magalhaes, L.; Oliveira, R. R. M.; Bonatto, S. L.; Barreto, S. B.; Kantek, D. L. Z.; Vilaca, S. T.

2026-08-06 genomics 10.64898/2026.07.31.742074 medRxiv
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The franciscana dolphin (Pontoporia blainvillei) is a small coastal cetacean endemic to the southwestern Atlantic Ocean and one of the most threatened marine mammals worldwide. It faces severe threats from bycatch, habitat degradation, and pollution. Classified as "Vulnerable" by the IUCN and "Critically Endangered" in Brazil, the species restricted range, strong fidelity to shallow waters, and low reproductive rate increase its extinction risk. Here, we present the first chromosome-level genome assembly for the franciscana dolphin, generated using PacBio HiFi long-read sequencing and Hi-C chromatin conformation capture. The final assembly totaled 3.13 Gb across 22 chromosomes (1500 scaffolds), consistent with the estimated karyotype of 2n = 44, with scaffold N50 of 111.18 Mb, high BUSCO completeness (99.42%), and a consensus quality value of 65.76. This high-quality genomic resource fills an important phylogenetic gap within Cetacea, enabling comparative and conservation studies. It provides an essential foundation for population genomics research to assess genetic diversity, structure, and connectivity, thereby supporting evidence-based conservation strategies for this endangered species.

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Sequencing, Chromosome-scale Assembly, and Annotation of the Genome of the Halophilic Nanoflagellate Halocafeteria seosinensis

Gallot-Lavallee, L.; Haro, R.; Jerlstrom-Hultqvist, J.; Tymoshenko, D.; Roger, A.; Archibald, J. M.

2026-06-30 genomics 10.64898/2026.06.25.734631 medRxiv
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Compared with bacterial and archaeal extremophiles, single-celled eukaryotes living in extreme habitats are understudied and underrepresented in genomic databases. An exception is the obligately halophilic stramenopile Halocafeteria seosinensis strain EHF34. A transcriptome-focused analysis of this extremophilic protists revealed the importance of organic osmolyte regulation and transport in its adaptation to hypersaline environments. However, genomic resources for H. seosinensis are currently limited to a highly fragmented assembly generated by short-read sequencing, which has hindered further investigation of the genome biology and evolution of this fascinating organism. Here, we used long-read Oxford Nanopore sequencing to generate a highly contiguous, chromosome-scale genome assembly for H. seosinensis. The assembly is 38.8 megabase pairs (Mbp) in size and contains 60 nuclear contigs, making it the most contiguous genome for a member of the order Bicosoecida. Approximately 19% of the genome is comprised of transposable elements. Of the 11,684 predicted protein-coding genes, many appear to be associated with DNA mobility-related functions, and several may be linked to adaptation to a hypersaline environment. Analysis of the H. seosinensis long-read genome assembly presented herein will facilitate our understanding of the ways in which protists have adapted to extreme environments. SignificanceHalocafeteria seosinensis is an extremophilic protist adapted to hypersaline environments. Previous analyses of a transcriptome and short-read draft genome assembly for this organism provided insights into the molecular mechanisms underlying osmotic regulation, which facilitate its adaptation to high-salt conditions. However, the lack of contiguity and quality of the draft assembly prevented the characterization of complex genomic regions, including transposable elements and viral insertions, as well as genomic comparisons with related species. Here we present a highly contiguous, chromosome-scale genome assembly for H. seosinensis that enables accurate gene prediction, detailed analysis of repeat content, and comparative genomic analysis. This long-read genome assembly will serve as a valuable resource for studying one of the few tractable halophilic protists sequenced to date.

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Characterization of an Arctic-like 1a rabies virus from a 54-day-old puppy with atypical presentation, Pune, India, 2026

Ullas, P. T.; Sharma, V.; Vipat, V.; Choudhari, S.; Ashraf, A. F.; Raju, R. M.; Kotturi, V.; Sakhare, K. S.; Bondre, V. P.

2026-07-13 infectious diseases 10.64898/2026.07.09.26357633 medRxiv
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Rabies remains a significantly underreported fatal zoonosis in India, where the Arctic-like 1a (AL1a) lineage predominates in dog populations. While atypical clinical presentations in dogs can delay diagnosis and increase human exposure risk, genomic and clinical data on neonatal canine rabies remain limited. This study reports an exceptional case of rabies in a 54-day old unvaccinated German shepherd puppy which presented with severe pruritus and self-biting behaviour. The puppy was euthanized due to poor clinical response. Post-mortem testing revealed viral antigen (by Direct Fluorescent Antibody Test) and viral RNA (by real-time RTPCR) in the brain tissue. Whole-genome sequencing recovered a near-complete rabies virus genome (11,947 nucleotides; 99.5% genome coverage), classified within the AL1a_A1.1 sublineage. Phylogenetic analysis revealed close genetic relatedness to contemporary Indian rabies virus strains. Comparative genomic analysis identified 4, 3, 6, and 8 non-synonymous substitutions in the phosphoprotein, matrix, glycoprotein, and polymerase genes, respectively. This case is one of the youngest documented cases of canine rabies with atypical manifestations, caused by the AL1a viral clade. Our findings highlight the risks associated with neonatal canine rabies, the need for heightened clinical suspicion in atypical cases, and the importance of genomic surveillance to monitor evolving rabies virus lineages in endemic regions.

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Description of canine- and feline-derived strains of the bile acid-converting bacterium Peptacetobacter hiranonis: P. hiranonis subsp. deconjugans subsp. nov. and P. hiranonis subsp. nondeconjugans subsp. nov.

Correa Lopes, B.; Turck, J.; Blake, A.; da Costa Medina, L. F.; Lawhon, S. D.; Suchodolski, J. S.; Pilla, R. K.

2026-08-22 microbiology 10.64898/2026.08.21.746369 medRxiv
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The bile acid-converting Peptacetobacter hiranonis is a Gram-positive, anaerobic, potentially spore-forming bacterium. It was first isolated from human feces and was subsequently shown to convert bile acids (BA) in both in vitro and in vivo experiments. The conversion of BA relies on the presence of the 7alpha-dehydroxylation multi-step pathway, encoded by the BA-inducible (bai) operon, harbored by P. hiranonis. In companion animals, P. hiranonis has been characterized as a biomarker for intestinal health, with its loss associated with dysbiosis. However, characterization of P. hiranonis cultured from companion animals is limited. An in-depth characterization of P. hiranonis was published by Chen et al. recently, including the proposal of a new species, Peptacetobacter hominis. We have sequenced the whole genome of both canine- and feline-derived strains of P. hiranonis, characterized these strains biochemically, and assessed their in vitro BA-converting ability as well as their antimicrobial resistance profiles. The strains described here can convert primary into secondary BAs and are whole-genome inhibited by low concentrations of amoxicillin-clavulanate, cefepime, ceftriaxone, chloramphenicol, ciprofloxacin, clindamycin, and metronidazole. Based on whole genome analysis, we propose dividing P. hiranonis into two host-adapted subspecies: P. hiranonis subsp. deconjugans and P. hiranonis subsp. nondeconjugans, based on their genomic differences and divergent ability to deconjugate BAs; a function that appears widely distributed among P. hiranonis strains cultured from dogs, but absent from those cultured from cats. Taken together, our results confirmed the BA conversion ability of P. hiranonis cultured from dogs and cats and reveal host-associated genomic and functional differences within the species.

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Genomics and biogeography of novel Trichodesmium isolates from the Sargasso Sea

Cleveland, C. S.; Bhatnagar, A. M.; Barnes, S. J.; Zhao, Y.; Webb, E. A.

2026-07-31 microbiology 10.64898/2026.07.30.741789 medRxiv
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The cyanobacterium Trichodesmium is important in ocean nitrogen (N) and carbon (C) biogeochemistry through fixation of N2 gas and CO2 into NH3, amino acids, and carbohydrates. These essential compounds then fuel primary productivity, bacterial and grazing communities, and upper trophic levels. In the oligotrophic surface oceans, they are one of few taxa capable of utilizing both atmospheric C and N. Trichodesmium fall into 2 diazotrophic phylogenomic clades named "Thieb" and "Tery" after the most well characterized botanical species, Trichodesmium thiebautii and Trichodesmium erythraeum. Thieb is commonly the most abundant clade in all major ocean regions and paradoxically, is also the least characterized in terms of morphology, genomics, and ecophysiology due to underrepresentation in culture collections. In this study, 25 novel strains of Thieb were enriched in culture from the Sargasso Sea, phenotypically characterized, and whole genome sequenced. Cultures were found to belong to four well-supported subclades (i.e., ThiebA, ThiebB, ThiebC, and ThiebD). Trichodesmium subclades were found to have environmentally relevant differences in colony shape, gene content, cell dimensions, and inferred temperature range. Specifically, ThiebD and ThiebC had the largest biovolumes whereas ThiebA and ThiebB had the smallest. Importantly ThiebB also became relatively more abundant only in bulk seawater metagenomes collected at high temperature (>28{degrees}C). This finding indicates that as ocean warming continues, there may be shifts in Trichodesmium community structure towards smaller cells, which would affect overall C+N standing stocks.

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Ruminococcus hollandia sp. nov. and Ruminococcus vasco sp. nov., two novel starch-degrading Ruminococcus isolated from the rumen of Holstein dairy cattle

Calapa, K. A.; Bock, R.; Embree, J.; LoBrutto, J.; Embree, M.

2026-07-11 microbiology 10.64898/2026.07.10.737842 medRxiv
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This study investigated the genomic and biochemical characteristics of two amylolytic microbial strains, NATIVEDY160T (= JE7B6T = NRRL B-68523T) and NATIVEDY161T (= JL13D9T, = NRRL B-68524T) isolated from the rumen of healthy Holstein dairy cattle. Both strains are obligately anaerobic, non-motile, Gram positive, catalase-negative, and oxidase-negative. Morphologically, NATIVEDY160T grows in long coccoid chains while NATIVEDY161T grows in short chains or pairs. NATIVEDY160T can catabolize amygdalin, esculin/ferric citrate, and starch, compared to NATIVEDY161T which utilizes amygdalin, arbutin, esculin/ferric citrate, glycogen, and D-maltose as determined by API 50 CH carbon panels. Starch degradation ability was verified for both strains, but neither showed cellulolytic activity as confirmed by starch agar and Congo red agar assays, respectively. HPLC analysis revealed that lactate was the primary end product of both strains carbohydrate fermentation, while strain NATIVEDY161T also produced small amounts of acetate. 16S rRNA sequences from both strains cluster with the Oscillospiraceae (formerly Ruminococcaceae) lineage Ruminococcus species, but average nucleotide identity of either strain compared to closely related Ruminococcus members was under the species threshold (95%). Genomic, phylogenetic, and phenotypic interrogation support NATIVEDY160T and NATIVEDY161T as novel species. Each strain was isolated from the rumen of dairy cows located within the central valley of southern California, which has a rich history of Dutch and Basque dairy farm ownership and is still the case today in the region. In recognition of the contributions and heritage of the central and southern California dairy industry, the names Ruminococcus hollandia and Ruminococcus vasco are proposed with NATIVEDY160T and NATIVEDY161T as their respective type strains.

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Hidden diversity and expanded host range of sarthroviruses, including terrestrial vertebrates

Mandojana, E.; Lim, L.; Melade, J.; Rieken, J.; Hall, J.; Petrone, M. E.; Mifsud, J. C. O.; Marzinelli, E. M.; Rose, K.; Holmes, E. C.; Van Brussel, K.

2026-06-16 microbiology 10.64898/2026.06.16.732546 medRxiv
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The Sarthroviridae are a family of highly compact satellite RNA viruses comprising one recognised species, extra small virus (XSV). Macrobrachium rosenbergii nodavirus (MrNV) is the associated helper virus of XSV and their co-infection has been linked to white tail disease in freshwater prawns globally, although the role of XSV is remains unclear. Here, we describe the discovery and characterisation of ten novel, highly divergent sarthrovirus species from a range of hosts and environments within a small geographical region in Australia. These comprise novel sarthroviruses associated with marine sponges, seal and dingo faeces, environmental marine sediment samples and Indo-Pacific geckos (Hemidactylus garnotii). All the novel viruses possess only a capsid protein, consistent with the genome of XSV, yet exhibit substantial sequence divergence. Notably, some sarthrovirus variants seem to utilise different replication systems despite being genetically identical and present in the same host species. Sequences from nodaviruses, which could plausibly act as helpers, were associated with some, but not all, the sarthroviruses identified here. Phylogenetic analyses support the expansion of the Sarthroviridae into multiple distinct lineages, comprising at least seven genera. Collectively, these findings reveal a broader ecological distribution and evolutionary diversity of sarthroviruses and highlight the possibility of alternative replication strategies and tissue tropism in diverse animal host. SignificanceSarthoviruses are small ([~]800 nucleotides) satellite RNA viruses associated with a nodavirus of crustaceans that acts as a helper. To date, the only known sarthovirus is extra small virus (XSV), which also represents the sole species within the Sarthroviridae. Here, we report the detection of ten divergent sarthroviruses sampled from diverse animal hosts, including vertebrates, that expand the family to 11 species and at least seven genera. These viruses were detected from various host taxa and environmental samples from a confined geographical region in eastern Australia, suggesting that they are ecologically connected. Notably, we did not detect nodaviruses in all samples containing sarthroviruses, suggesting that different viruses may act as helpers for sarthovirus replication.

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Reysenbachia aerophila gen. nov., sp. nov., a facultatively anaerobic, hydrogen-oxidizing, thermophilic bacterium isolated from Kuirau Park, Rotorua, New Zealand

Marshall, M. E. A.; Stott, M. B.; Welford, H. E.; Lagutin, K.; Mitchell, K. A.; Carere, C. R.

2026-06-15 microbiology 10.64898/2026.06.14.732183 medRxiv
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A facultatively anaerobic, hydrogen-oxidizing, thermophilic bacterium (strain KUI-RBT) was isolated from a geothermal spring biofilm in Rotorua, New Zealand. Strain KUI-RBT is a motile, straight rod, measuring approximately 0.7 {micro}m by 1.0 to 1.5 {micro}m with a diderm cell wall. Growth of KUI-RBT occurred from 39 to 74 {degrees}C (Topt 64.5 {degrees}C), pH 5.0 to 7.5 (pHopt 6.5), and 0 to 1% (w/v) NaCl (NaClopt 0.4-0.7%, w/v). KUI-RBT utilizes carbon dioxide and various organic carbon substrates as carbon sources and hydrogen as an electron donor. KUI-RBT can use oxygen (0-21%, v/v), elemental sulfur, thiosulfate, sulfite, nitrate, arsenate, and selenate as terminal electron acceptors. Major fatty acids of strain KUI-RBT include C20:1, C18:1, and C18:0 and the primary quinone is MTK-7. The whole genome G+C content is 34.23 mol%. Phylogenetic analyses indicate KUI-RBT to be a member of the family Hydrogenothermaceae, with Sulfurihydrogenibium azorense Az-Fu1T its closest characterised relative (94.51% 16S rRNA gene sequence similarity, 78.01% whole genome ANI, 61.34% whole genome AAI). Based on phylogenetic and phenotypic analyses, we propose KUI-RBT represents a novel genus and species within the family Hydrogenothermaceae, for which we propose the name Reysenbachia aerophila gen. nov., sp. nov. The type strain is KUI-RBT (=KCTC accession =JCM accession). The GenBank accession number for the 16S rRNA gene sequence of strain KUI-RBT is PZ052650. The GenBank accession number for the whole genome of strain KUI-RBT is JBVODP000000000.