Azospirillum formosense sp nov., a diazotroph from agricultural soil

A Gram-negative, spiral or rod-shaped, non-spore-forming diazotrophic bacterium, designated CC-Nfb-7(T), was isolated from agricultural soil in Yunlin County, Taiwan. 16S rRNA gene sequence analysis showed that strain CC-Nfb-7(T) was most closely related to Azospirillum brasilense DSM 1690(T) (97.4% 16S rRNA gene sequence similarity), Azospirillum rugosum IMMIB AFH-6(T) (96.8%) and Azospirillum oryzae JCM 21588(T) (96.6 %); <96.5% 16S rRNA gene sequence similarity was found with all other members of the genus Azospirillum. DNA-DNA relatedness between strain CC-Nfb-7(T) and A. brasilense DSM 1690(T), A. rugosum DSM 19657(T) and A. oryzae JCM 21588(T) was 38.9, 30.1 and 31.8%, respectively. The respiratory quinone was ubiquinone Q-10. The major fatty acids were summed feature 8 (consisting of C-18:1 omega 7c and/or C(18:1)w6c), summed feature 3 (consisting of C-16:1 omega 7c and/or C-16:1 omega 6c), summed feature 2 (consisting of C-14:0 3-OH and/or iso-C-16:1 I), C-16:0, C-18:0 2-OH and C-16:0 3-OH. The polar lipids consisted mainly of phosphatidylglycerol, phosphatidylcholine and one unidentified phospholipid. Furthermore, moderate amounts of phosphatidylethanolamine, phosphatidyl-dimethylethanolamine and one unidentified aminophospholipid were also detected. Strain CC-Nfb-7(T) could be distinguished from members of phylogenetically related species by differences in phenotypic properties. On the basis of morphological, chemotaxonomic and phylogenetic data, strain CC-Nfb-7(T) represents a novel species within the genus Azospirillum, for which we propose the name Azospirillum formosense sp. nov. The type strain is CC-Nfb-7(T) (=BCRC 80273(T)=JCM 17639(T)=DSM 24137(T)).