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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.

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Title: 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.
Authors: Candia-Herrera D; Instituto De Investigaciones Agropecuarias (INIA), Av. Vicente Méndez, 515, Chillán, Chile., Guerra M; Instituto De Investigaciones Agropecuarias (INIA), Av. Vicente Méndez, 515, Chillán, Chile., Carrasco-Fernández J; Instituto De Investigaciones Agropecuarias (INIA), Av. Vicente Méndez, 515, Chillán, Chile., Campos-Quiroz C; Instituto De Investigaciones Agropecuarias (INIA), Av. Vicente Méndez, 515, Chillán, Chile., Garcia-Gomez M; Microbiology and Genetics Department, University of Salamanca, Salamanca, Spain; Institute of Investigation in Agrobiotechnology (CIALE), Villamayor De La Armuña, Salamanca, Spain., Igual JM; Unidad Asociada De Investigación En Interacción Planta-Microorganismo, USAL-CSIC (IRNASA), 37008 Salamanca, Spain; Instituto De Recursos Naturales Y Agrobiología De Salamanca, Consejo Superior De Investigaciones Científicas (IRNASA-CSIC), c/Cordel De Merinas 40-52, 37008 Salamanca, Spain., Carro L; Microbiology and Genetics Department, University of Salamanca, Salamanca, Spain; Institute of Investigation in Agrobiotechnology (CIALE), Villamayor De La Armuña, Salamanca, Spain; Unidad Asociada De Investigación En Interacción Planta-Microorganismo, USAL-CSIC (IRNASA), 37008 Salamanca, Spain; Unidad De Excelencia Producción, Agrícola Y Medioambiente (AGRIENVIRONMENT), Universidad De Salamanca, 37185 Salamanca, Spain., Castro JF; Instituto De Investigaciones Agropecuarias (INIA), Av. Vicente Méndez, 515, Chillán, Chile. Electronic address: jean.castro@inia.cl.
Source: Systematic and applied microbiology [Syst Appl Microbiol] 2026 Jul; Vol. 49 (4), pp. 126734. Date of Electronic Publication: 2026 May 26.
Publication Type: Journal Article
Language: English
Journal Info: Publisher: Elsevier GmbH Country of Publication: Germany NLM ID: 8306133 Publication Model: Print-Electronic Cited Medium: Internet ISSN: 1618-0984 (Electronic) Linking ISSN: 07232020 NLM ISO Abbreviation: Syst Appl Microbiol Subsets: MEDLINE
Imprint Name(s): Publication: [Munich, Germany] : Elsevier GmbH
Original Publication: Stuttgart ; New York : G. Fischer Verlag, c1983-
MeSH Terms: Bacillaceae*/classification , Bacillaceae*/genetics , Bacillaceae*/isolation & purification , Genome, Bacterial*/genetics , Phylogeny* , Soil Microbiology*, DNA, Bacterial/genetics ; RNA, Ribosomal, 16S/genetics ; Fatty Acids/chemistry ; Sequence Analysis, DNA ; Bacterial Typing Techniques ; Base Composition
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).
(Copyright © 2026 Elsevier GmbH. All rights reserved.)
Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
Comments: Erratum in: Syst Appl Microbiol. 2026 Sep 5:126758. doi: 10.1016/j.syapm.2026.126758.. (PMID: 42701064)
Contributed Indexing: Keywords: Metabacillus; New genera; Novel species; Polyphasic taxonomy
Substance Nomenclature: 0 (DNA, Bacterial)
0 (RNA, Ribosomal, 16S)
0 (Fatty Acids)
Entry Date(s): Date Created: 20260603 Date Completed: 20260704 Latest Revision: 20260905
Update Code: 20260906
DOI: 10.1016/j.syapm.2026.126734
PMID: 42235107
Database: MEDLINE
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  Data: 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.
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  Data: <searchLink fieldCode="AU" term="%22Candia-Herrera+D%22">Candia-Herrera D</searchLink>; Instituto De Investigaciones Agropecuarias (INIA), Av. Vicente Méndez, 515, Chillán, Chile.<br /><searchLink fieldCode="AU" term="%22Guerra+M%22">Guerra M</searchLink>; Instituto De Investigaciones Agropecuarias (INIA), Av. Vicente Méndez, 515, Chillán, Chile.<br /><searchLink fieldCode="AU" term="%22Carrasco-Fernández+J%22">Carrasco-Fernández J</searchLink>; Instituto De Investigaciones Agropecuarias (INIA), Av. Vicente Méndez, 515, Chillán, Chile.<br /><searchLink fieldCode="AU" term="%22Campos-Quiroz+C%22">Campos-Quiroz C</searchLink>; Instituto De Investigaciones Agropecuarias (INIA), Av. Vicente Méndez, 515, Chillán, Chile.<br /><searchLink fieldCode="AU" term="%22Garcia-Gomez+M%22">Garcia-Gomez M</searchLink>; Microbiology and Genetics Department, University of Salamanca, Salamanca, Spain; Institute of Investigation in Agrobiotechnology (CIALE), Villamayor De La Armuña, Salamanca, Spain.<br /><searchLink fieldCode="AU" term="%22Igual+JM%22">Igual JM</searchLink>; Unidad Asociada De Investigación En Interacción Planta-Microorganismo, USAL-CSIC (IRNASA), 37008 Salamanca, Spain; Instituto De Recursos Naturales Y Agrobiología De Salamanca, Consejo Superior De Investigaciones Científicas (IRNASA-CSIC), c/Cordel De Merinas 40-52, 37008 Salamanca, Spain.<br /><searchLink fieldCode="AU" term="%22Carro+L%22">Carro L</searchLink>; Microbiology and Genetics Department, University of Salamanca, Salamanca, Spain; Institute of Investigation in Agrobiotechnology (CIALE), Villamayor De La Armuña, Salamanca, Spain; Unidad Asociada De Investigación En Interacción Planta-Microorganismo, USAL-CSIC (IRNASA), 37008 Salamanca, Spain; Unidad De Excelencia Producción, Agrícola Y Medioambiente (AGRIENVIRONMENT), Universidad De Salamanca, 37185 Salamanca, Spain.<br /><searchLink fieldCode="AU" term="%22Castro+JF%22">Castro JF</searchLink>; Instituto De Investigaciones Agropecuarias (INIA), Av. Vicente Méndez, 515, Chillán, Chile. Electronic address: jean.castro@inia.cl.
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  Data: 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-250<superscript>T</superscript>, 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-250<superscript>T</superscript> (=RGM 3146<superscript>T</superscript> = IMI 507634<superscript>T</superscript>).<br /> (Copyright © 2026 Elsevier GmbH. All rights reserved.)
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  Data: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
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  Data: Erratum in: Syst Appl Microbiol. 2026 Sep 5:126758. doi: 10.1016/j.syapm.2026.126758.. (PMID: <searchLink fieldCode="PM" term="%2242701064%22">42701064)</searchLink>
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      – SubjectFull: RNA, Ribosomal, 16S genetics
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              Text: 2026 Jul
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