Azospirillum soli sp nov., a nitrogen-fixing species isolated from agricultural soil

An aerobic, Gram-stain-negative, rod or spiral-shaped diazotrophic bacterium (designated strain CC-LY788(T)), was isolated from agricultural soil in Taiwan. Strain CC-LY788(T) was able to grow at 25-40 degrees C, pH 6.0-8.0 and tolerated NaCl to 2.0% (w/v). Positive for nitrogen fixation with the activity recorded as 6.5 nmol ethylene h(-1). Strain CC-LY788(T) showed highest 16S rRNA gene sequence similarity to Azospirillum picis DSM 19922(T) (97.2%) and Azospirillum rugosum DSM 19657(T) (97.1%) and lower sequence similarities (<96.6%) to all other species of the genus Azospirillum. According to the DNA-DNA hybridization, the relatedness values of strain CC-LY788(T) with A. picis DSM 19922(T) and A. rugosum DSM 19657(T) were 51.1 +/- 5.5% and 46.8 +/- 2.1%, respectively. Strain CC-LY788(T) was positive for the rapid identification of the genus-specific primer set. The respiratory quinone system was ubiquinone (Q-10) and the DNA G-FC content was 69.8 mol%. The major fatty acids found in strain CC-LY788(T) were C-16 : 0, C-18 : 1 2-OH, C-14 : 0 3-OH/C-16 : 1 iso I (summed feature 2), C-16 :1 omega 7c/C-16 : 1 omega 6c (summed feature 3), C-18 : 0 ante/C-18 : 2 omega 6,9c (summed feature 5) and C-18 : 1 omega 7c/C-18 :1 omega 6c (summed feature 8). Based on the phylogenetic, phenotypic and chemotaxonomic features, strain CC-LY788(T) represents a novel species of the genus Azospirillum, for which the name Azospirillum soli sp. nov. is proposed. The type strain is CC-LY788(T) (=BCRC 80569(T)=JCM 18820(T)).