Whole genome-based reclassification of the genus Metabacillus: Proposal for five novel genera, Chryseobacillus gen. nov., Cohnibacillus gen. nov., Salimetabacillus gen. nov., Pantoeobacillus gen. nov., and Lutimetabacillus gen. nov. and the description of one novel bacterial species, Chryseobacillus diguaensis sp. nov. isolated from soil in the Digua reservoir.

Daniel Candia-Herrera; Mat&#xed;as Guerra; Jorge Carrasco-Fern&#xe1;ndez; Carolina Campos-Quiroz; Marina Garcia-Gomez; Jos&#xe9; M Igual; Lorena Carro; Jean Franco Castro

doi:10.1016/j.syapm.2026.126734

PubMed · 42235107

Whole genome-based reclassification of the genus Metabacillus: Proposal for five novel genera, Chryseobacillus gen. nov., Cohnibacillus gen. nov., Salimetabacillus gen. nov., Pantoeobacillus gen. nov., and Lutimetabacillus gen. nov. and the description of one novel bacterial species, Chryseobacillus diguaensis sp. nov. isolated from soil in the Digua reservoir.

Daniel Candia-Herrera·Matías Guerra·Jorge Carrasco-Fernández·Carolina Campos-Quiroz·Marina Garcia-Gomez·José M Igual·Lorena Carro·Jean Franco Castro

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Abstract

Comprehensive phylogenomic and comparative genomic analyses were conducted to clarify the taxonomic boundaries of the genus Metabacillus. Phylogenetic trees reconstructed from a set of single-copy orthologous proteins (SCOPs) revealed that the genus, as currently defined, is polyphyletic. The type species of the genus Metabacillus and its closest relatives formed a consistent clade, herein designated as Metabacillus sensu stricto. The remaining species were grouped into three well-supported clades: Kandeliae, Indicus, and Mangrovi, and two single-taxon lineages: M. arenae and M. lacus. The phylogenomic delineation found in these divergent taxa was corroborated by either inconsistent distribution patterns or the absence of previously defined conserved signature indels (CSIs) specific to Metabacillus. Genomic metrics, including Average Nucleotide Identity (ANI), Average Amino acid Identity (AAI), and digital DNA-DNA hybridization (dDDH) further supported the taxonomic delineation proposed here. The observed genomic divergence was mirrored by phenotypic differences, including variations in GC content ranges. Based on this polyphasic evidence, we propose the reclassification of the genus Metabacillus taxa into five novel genera: Chryseobacillus gen. nov. (encompassing the Kandeliae clade), Cohnibacillus gen. nov. (M. lacus), Salimetabacillus gen. nov. (M. arenae), Pantoeobacillus gen. nov. (Indicus clade), and Lutimetabacillus gen. nov. (Mangrovi clade). The core lineage is retained as Metabacillus sensu stricto, for which an emended description of the genus Metabacillus is also provided. A novel bacterial strain, designated as MAU-250T, was isolated from a soil sample collected on the shore of an artificial reservoir in the Andean foothills of the Maule Region in central Chile. Public metagenome screening supported a low-abundance taxon with broad ecological adaptability, preferentially associated with soil habitats. A polyphasic analysis based on phenotypic traits and genomic distances (78.0% ANIb and 19.8% dDDH against its closest relative) also supported its designation as a novel species, for which the name Chryseobacillus diguaensis sp. nov. is proposed. The type strain is MAU-250T (=RGM 3146T = IMI 507634T).

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Phylogeny DNA, Bacterial RNA, Ribosomal, 16S Bacillaceae Genome, Bacterial Soil Microbiology Sequence Analysis, DNA Bacterial Typing Techniques Base Composition Fatty Acids Metabacillus New genera Novel species Polyphasic taxonomy Journal Article

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Daniel Candia-Herrera, Matías Guerra, Jorge Carrasco-Fernández, Carolina Campos-Quiroz, Marina Garcia-Gomez, José M Igual, Lorena Carro, Jean Franco Castro. 2026-05-26. Whole genome-based reclassification of the genus Metabacillus: Proposal for five novel genera, Chryseobacillus gen. nov., Cohnibacillus gen. nov., Salimetabacillus gen. nov., Pantoeobacillus gen. nov., and Lutimetabacillus gen. nov. and the description of one novel bacterial species, Chryseobacillus diguaensis sp. nov. isolated from soil in the Digua reservoir.. https://doi.org/10.1016/j.syapm.2026.126734

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