Publications

4369

AbstractThe Candidate Phyla Radiation (CPR) constitutes a large group of mostly uncultured bacterial lineages with small cell sizes and limited biosynthetic capabilities. They are thought to be symbionts of other organisms, but the nature of this symbiosis has been ascertained only for cultured Saccharibacteria, which are epibiotic parasites of other bacteria. Here, we study the biology and the genome of Vampirococcus lugosii, which becomes the first described species of Vampirococcus, a genus of epibiotic bacteria morphologically identified decades ago. Vampirococcus belongs to the CPR phylum Absconditabacteria. It feeds on anoxygenic photosynthetic gammaproteobacteria, fully absorbing their cytoplasmic content. The cells divide epibiotically, forming multicellular stalks whose apical cells can reach new hosts. The genome is small (1.3 Mbp) and highly reduced in biosynthetic metabolism genes, but is enriched in genes possibly related to a fibrous cell surface likely involved in interactions with the host. Gene loss has been continuous during the evolution of Absconditabacteria, and generally most CPR bacteria, but this has been compensated by gene acquisition by horizontal gene transfer and de novo evolution. Our findings support parasitism as a widespread lifestyle of CPR bacteria, which probably contribute to the control of bacterial populations in diverse ecosystems.

Abstract Zebra chip, is a potato disease associated with the bacterium ‘Candidatus Liberibacter solanacearum’ (Lso) and vectored by the potato psyllid, Bactericera cockerelli Šulc. Potato psyllids are native to North America, where four haplotypes have been described. They are able to colonize a wide range of solanaceous species, crops, and weeds. The epidemiology of zebra chip disease is still poorly understood and might involve the different haplotypes of psyllids as well as two haplotypes of Lso. As several perennial weeds have been recognized as potential host for potato psyllids and Lso, a yearly monitoring of several patches of bittersweet nightshade (Solanum dulcamara) and field bindweed (Convolvulus arvensis) located in the potato-growing region of southern Idaho was conducted from 2013 to 2017, to gain insight into psyllid dynamics in non-potato hosts and Lso presence in the fields. Potato psyllids caught on each host were individually tested for Lso, and a subset were haplotyped based on the CO1 gene, along with the haplotyping of Lso in positive samples. On bittersweet nightshade, the Northwestern haplotype was numerically dominant, with around 2.7% of psyllids found to be carrying either Lso haplotype A or B, suggesting a limited role in zebra chip persistence, which has infected Idaho fields at a low occurrence since the 2012 outbreak. Field bindweed was found to be a transient, non-overwintering host for potato psyllid of Northwestern, Western and Central haplotypes late in the season, suggesting minor, if any, role in persistence of Lso and field infestation by potato psyllids.

Background and Aim: Hemoplasmas are defined as small, epicellular parasitic bacteria that can infect the red blood cells of several mammalian species. Diseases caused by these bacteria range from asymptomatic infections to acute hemolytic anemia. However, data on hemoplasmas in non-human primates in Thailand remain to be limited. Therefore, this study aims to determine the occurrence and genetic diversity of hemoplasmas among long-tailed macaques in Thailand. Materials and Methods: Blood samples were collected from 339 long-tailed macaques in three provinces of Thailand. DNA was then extracted from the blood samples and tested for hemoplasma using broad-range nested polymerase chain reaction (PCR) based on the 16S rRNA gene. PCR-positive samples were sequenced, and phylogenetic analysis for species identification was conducted. Results: In total, 38 (11.2%) out of the 339 samples were found to be positive for hemoplasmas, based on the broad-range nested PCR assay of the 16S rRNA gene. The 16S rRNA sequences of Mycoplasma spp. were highly similar (98-99% identity) to "Candidatus Mycoplasma haemomacaque." Furthermore, phylogenetic analysis using maximum likelihood demonstrated that the sequences were located in the same cluster of "Ca. M. haemomacaque." Conclusion: The detection of hemoplasmas among long-tailed macaques in Thailand is reported. Genetic characterization confirmed that these hemoplasmas are closely related to "Ca. M. haemomacaque." These results indicate that long-tailed macaques in several locations in Thailand may be infected and serve as reservoirs for this parasite.

Abstract Phytoplasmas are wall-less, phloem-limited unculturable bacteria that are naturally spread by sap-sucking insects. 'Candidatus Phytoplasma australiense', subgroup 16SrXII-B, is associated with a wide range of diseases in Australia and New Zealand. Important commercial crop hosts of 'Ca. Phytoplasma australiense' include grapevine, papaya and strawberry. This phytoplasma is associated with rapid death of its papaya and cabbage tree hosts. In New Zealand, the insect vectors have been confirmed to be the endemic Cixiid planthoppers, Zeoliarus atkinsoni and Z. oppositus, while in Australia no vector has yet been determined, although the leafhopper, Orosius argentatus, has been implicated. Long distance spread of the phytoplasma is possible through infected vegetative propagating material. 'Ca. Phytoplasma australiense' is on the A1 list of regulated organisms for Canada and Bahrain, and is listed as a quarantine pest for the USA.

Abstract The Atlantic tall, the most prevalent coconut ecotype throughout the Caribbean region and Atlantic coast of the Americas (Harries, 1978a), is highly susceptible to LY disease. During the past three decades, at least 50% of Florida's estimated one million coconut palms and over 80% of Jamaica's five million coconut palms have been eliminated by LY (McCoy et al., 1983). Similar epidemic losses of coconut to LY continued along the Atlantic coasts of southern Mexico and Honduras (Oropeza and Zizumbo, 1997). Although rarely affecting palms less than 5 years old, the disease prevents any re-establishment of highly susceptible coconut ecotypes in LY-endemic locations such as Florida and Jamaica.

Abstract Hal.ec.to.sym.bi.o'ta. Gr. masc. n. hals , halos salt, salt water; Gr. prep. ektos outside; N.L. masc. n. symbiota (from Gr. n. symbiotes ) one who lives with a companion, partner; N.L. masc. n. Halectosymbiota an ectosymbiont from salt water organisms. The genus Candidatus Halectosymbiota corrig., originally described as Ca . Haloectosymbiotes, was established based on a 16S rRNA taxonomic marker gene sequence of the only identified species in this genus, Candidatus Halectosymbiota riaformosensis. Ca . Halectosymbiota riaformosensis was observed to live as ectosymbiont on a halophile scuticociliate, which was isolated from a thalassohaline solar saltern pond (12% salinity) in Faro, Portugal. Comparisons of 16S rRNA gene sequences showed that Ca . Halectosymbiota is phylogenetically affiliated to the genera Halolamina (sequence similarity to H. pelagica : 87%) and Halobaculum (sequence similarity to H. magnesiiphilum 85%). Based on scanning electron microscopy micrographs and fluorescence in situ hybridization, cells are rod‐shaped and approximately 1.8 × 0.6 μm in size. Cells are densely covering the surface of the host, with approximately 0.52 epibiotic cells per μm 2 . Free‐living forms were not observed. Candidatus Halectosymbiota riaformosensis is sensitive to anisomycin. Known habitats are aquatic hypersaline environments. Type species : Not applicable. Taxonomic and Nomenclature Notes According to the List of Prokaryotic names with Standing in Nomenclature (LPSN), the taxonomic status of the genus Candidatus Halectosymbiota is: preferred name (not correct name) (last update, February 2025) * . LPSN classification: Archaea / Methanobacteriati / Methanobacteriota / Halobacteria / Halobacteriales / Halobacteriaceae / Candidatus Halectosymbiota Candidatus Halectosymbiota could not be recovered in GTDB ** . * Meier‐Kolthoff et al. ( 2022 ). Nucleic Acids Res , 50 , D801 – D807 ; DOI: 10.1093/nar/gkab902 ** Parks et al. ( 2022 ). Nucleic Acids Res , 50 , D785 – D794 ; DOI: 10.1093/nar/gkab776

Background The chicken is the most abundant food animal in the world. However, despite its importance, the chicken gut microbiome remains largely undefined. Here, we exploit culture-independent and culture-dependent approaches to reveal extensive taxonomic diversity within this complex microbial community. Results We performed metagenomic sequencing of fifty chicken faecal samples from two breeds and analysed these, alongside all (n = 582) relevant publicly available chicken metagenomes, to cluster over 20 million non-redundant genes and to construct over 5,500 metagenome-assembled bacterial genomes. In addition, we recovered nearly 600 bacteriophage genomes. This represents the most comprehensive view of taxonomic diversity within the chicken gut microbiome to date, encompassing hundreds of novel candidate bacterial genera and species. To provide a stable, clear and memorable nomenclature for novel species, we devised a scalable combinatorial system for the creation of hundreds of well-formed Latin binomials. We cultured and genome-sequenced bacterial isolates from chicken faeces, documenting over forty novel species, together with three species from the genus Escherichia, including the newly named species Escherichia whittamii. Conclusions Our metagenomic and culture-based analyses provide new insights into the bacterial, archaeal and bacteriophage components of the chicken gut microbiome. The resulting datasets expand the known diversity of the chicken gut microbiome and provide a key resource for future high-resolution taxonomic and functional studies on the chicken gut microbiome.