sp. nov., a plant growth-promoting bacterium isolated from yam ( species).

This study investigated endophytic nitrogen-fixing bacteria isolated from two species of yam (water yam, L.; lesser yam, L.) grown in nutrient-poor alkaline soil conditions on Miyako Island, Okinawa, Japan. Two bacterial strains of the genus , S-93 and S-62, were isolated. The phylogenetic tree, based on the almost-complete 16S rRNA gene sequences (1476 bp for each strain), placed them in a distinct clade, with CCBAU 41251, I66, HAMBI 2975, PRF 81 and CIAT 899 being their closest species. Their bacterial fatty acid profile, with major components of C cyclo 8 and summed feature 8, as well as other phenotypic characteristics and DNA G+C content (59.65 mol%) indicated that the novel strains belong to the genus . Pairwise average nucleotide identity analyses separated the novel strains from their most closely related species with similarity values of 90.5, 88.9, 88.5, 84.5 and 84.4 % for HAMBI 2975, CIAT 899, CCBAU 57015, HAMBI 2971 and PRF 81, respectively; digital DNA-DNA hybridization values were in the range of 26-42 %. Considering the phenotypic characteristics as well as the genomic data, it is suggested that strains S-93 and S-62 represent a new species, for which the name is proposed. The type strain is S-93 (=NRIC 0988=NBRC 114257=DSM 110498).