sp. nov., a novel strain with plant growth-promoting properties.

A phosphate-solubilizing bacterial strain, designated C3, was isolated from the rhizosphere of sorghum. The taxonomic classification of this novel isolate was investigated by using a polyphasic approach. Cells of this strain were Gram-stain-negative, facultatively anaerobic and motile short rods with a polar flagellum. Phylogenetic analyses based on the 16S rRNA gene indicated that strain C3 showed high similarity (98.66%) to certain species, indicating that the isolate belongs to this genus. The genome of strain C3 was 5.05 Mb in size with a G+C content of 51.1 mol%. Whole-genome analysis revealed that the novel strain shared 21.60-27.10% digital DNA-DNA hybridization values and 78.35-83.87% average nucleotide identity with closely related species; both values below the accepted thresholds for defining a novel species. The predominant cellular fatty acids of strain C3 were C, summed feature 3 (C ω6c and/or C ω7c), summed feature 8 (C ω7c and/or C ω6c), summed feature 2 (C aldehyde and/or C 3OH and/or C iso I and/or an unidentified fatty acid of 10.9525 chain length) and C cyclo. Apart from the ability to solubilize phosphates, stain C3 exhibited other plant growth-promoting activities such as K, Ca and Si solubilization, and the production of indole-3-acetic acid (IAA) and siderophores. Several genes related to phosphate solubilization, siderophore biogenesis and IAA, cytokinin and gamma-aminobutyric acid production were identified in the C3 genome. Summarizing, based on phylogenetic, genomic, phenotypic and chemotaxonomic criteria, the isolate represents a novel species of the genus for which the name sp. nov. is proposed. The type strain is C3 (=CECT 31163=NCIMB 15596).