Expansion and revision of the genus and proposal of gen. nov.

International journal of systematic and evolutionary microbiology
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Keywords
Abstract

The nitrogen-fixing, chemolithoautotrophic genus is found across numerous diverse environments worldwide and is an important member of many ecosystems. These species serve as model systems for their metabolic properties and have industrial applications in bioremediation and sustainable protein, food and fertilizer production. Despite their abundance and utility, the majority of strains are without a genome sequence, and only eight validly published species are known to date. To expand our understanding of the diversity and evolutionary history of the genus, we sequenced the genomes of 37 repository strains and 26 novel environmental strains we isolated. After performing comparative phylogenomic analyses, we expand and revise the genus and propose the novel genus gen. nov. For , we describe 9 novel species (bringing the total to 17): sp. nov. (V0C-6=DSM 117699=ATCC TSD-450), sp. nov. (V4C-4=DSM 117704=ATCC TSD-451), sp. nov. (V3C-3=DSM 117706=ATCC TSD-452), sp. nov. (14g=DSM 431=JCM 1201=CIP 105432=NCIMB 10811), sp. nov. (KA=DSM 11602=KCTC 8467), sp. nov. (V8C-5=DSM 117708=ATCC TSD-453), sp. nov. (V4C-8=DSM 117713=ATCC TSD-454), sp. nov. (Py2=DSM 118458=ATCC BAA-1158) and sp. nov. (RH 10=DSM 597=JCM 7864=CIP 105437). For gen. nov., we describe five novel species formerly classified as : sp. nov. (VTT E-85241=BIO GISA 20=DSM 117884), sp. nov. (VTT E-85242=BIO GISA 21=DSM 117885), sp. nov. (VTT E-85238=BIO GISA 16=DSM 117882), sp. nov. (VTT E-85240=BIO GISA 19=DSM 117883) and sp. nov. (W30=DSM 24535=KCTC 8466). We characterized the phenotypic properties of these type strains, including temperature, salinity and pH ranges, carbon substrate utilization, motility, slime production, autotrophic growth and enzymatic activities. We discovered a more diverse range of phenotypes across the genus than previously known and elucidated the evolutionary history within the genus. These findings and genome sequences will help further the application of biology in academic, industrial and environmental settings and provide additional insight into the unique biological properties that make these species attractive for such applications.

Year of Publication
2025
Journal
International journal of systematic and evolutionary microbiology
Volume
75
Issue
9
Date Published
09/2025
ISSN
1466-5034
DOI
10.1099/ijsem.0.006909
PubMed ID
40928969
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