Exploring the Diversity of the Genus Nitrospirillum: Description of Six Novel Nitrogen-Fixing Bacteria Species
Listed in
This article is not in any list yet, why not save it to one of your lists.Abstract
In this study, we characterized 86 plant growth-promoting bacterial strains belonging to the genus Nitrospirillum , isolated from diverse host plants and geographic regions. To investigate their evolutionary relationships, we employed phylogenetic analyses based on 16S rRNA and recA genes, as well as phylogenomic approaches including average nucleotide identity (ANI) and digital DNA–DNA hybridization (dDDH). The classification of type strains was further supported by in silico analyses of chemotaxonomic markers, particularly genes involved in fatty acid biosynthesis and elongation, phospholipid and quinone production, and nitrogen fixation ( nifHDK operon). Phenotypic and chemotaxonomic characterization was performed using matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry, fatty acid methyl ester (FAME) profiling, and physiological assays. These included evaluations of nitrogen fixation capacity, antibiotic resistance, carbon source utilization, and enzymatic activity. This integrative approach provided detailed insight into the characteristics and diversity of the studied strains. Phylogenetic and genomic analyses revealed six novel taxa within the genus Nitrospirillum , in addition to the previously described species N. amazonense , N. iridis , and N. viridazoti . The distinctiveness of these new lineages was supported by both genomic metrics and phenotypic traits. All novel strains also exhibited ethylene production, confirming their nitrogen-fixing ability under in vitro conditions. Based on these findings, we propose the formal description of six novel species: Nitrospirillum bahiense sp. nov. (= BR 11865ᵀ, =UCCCB 233ᵀ), Nitrospirillum guanabarense sp. nov. (= BR 11163ᵀ, =UCCCB 228ᵀ), Nitrospirillum guaranorum sp. nov. (= BR 11164ᵀ, =UCCCB 229ᵀ), Nitrospirillum karajorum sp. nov. (= BR 11752ᵀ, =UCCCB 231ᵀ), Nitrospirillum guiasense sp. nov. (= BR 11828ᵀ, =UCCCB 232ᵀ), and Nitrospirillum pindoramense sp. nov. (= BR 11622ᵀ, =UCCCB 230ᵀ).
