Candidatus Mancarchaeum

Abstract Manc.ar.chae'um. L. masc. adj. mancus , crippled, maimed; N.L. neut. n. archaeum , an archaeon; N.L. neut. n. Mancarchaeum , a crippled archaeon, an archaeon with absence of many pathways in the genome. The archaeon Candidatus Mancarchaeum was identified in a binary culture during the isolation of Cuniculiplasma divulgatum strain PM4. The culture was established with water saturated sediment sample from acidic stream flowing on Parys Mountain copper mine, Isle of Anglesey, UK. The proportion of genomic reads of Ca . Mancarchaeum in the binary culture was ca. 10%. Ca . Mancarchaeum is phylogenetically affiliated with members of the phylum Microcaldota , class Microcaldia , order Ca . Micrarchaeales, family Ca . Micrarchaeaceae. The cultivation experiments and analysis of the 952,257 bp genome suggest aerobic/microaerobic, organoheterotrophic (proteolytic/peptidolytic), acidophilic, and mesophilic lifestyle. The genome analysis showed the lack of complete central pathways and limited respiratory capacities, indicating reliance on the host, in that particular case, C. divulgatum PM4. The metagenomic analysis also suggested the lateral gene transfer events between the Ca . Mancarchaeum and host in situ . Ca . Mancarchaeum was found as a minor member of microbial community of Parys Mountain acid mine drainage stream. Further environmental distribution of representatives of this Candidatus genus showed preferences to habitats with low pHs and temperatures between 35 and 50°C. DNA G + C content (mol%) : 39.5 (genome sequence). Type species : Candidatus Mancarchaeum acidiphilum Golyshina et al. 2017, CL1. Taxonomic and Nomenclature Notes According to the List of Prokaryotic names with Standing in Nomenclature (LPSN), the taxonomic status of the genus Candidatus Mancarchaeum is: preferred name (not correct name) (last update, February 2025) * . LPSN classification: Archaea / Nanobdellati / Candidatus Micrarchaeota / Candidatus Micrarchaeia / Candidatus Micrarchaeales / Candidatus Micrarchaeaceae / Candidatus Mancarchaeum The genus Candidatus Mancarchaeum can also be recovered in the Genome Taxonomy Database (GTDB) as g__Mancarchaeum (version v220) ** . GTDB classification: d__Archaea / p__Micrarchaeota / c__Micrarchaeia / o__Micrarchaeales / f__Micrarchaeaceae / g__Mancarchaeum * 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