Azospirillum tabaci sp. nov., a bacterium isolated from rhizosphere soil of Nicotiana tabacum L

Strain W712(T) was isolated from rhizosphere soil of Nicotiana tabacum L. collected from Kunming, south-west China. Cells were Gram-staining negative, aerobic, motile and rod shaped. The isolate grew at 20-45 degrees C (optimum 30 degrees C), pH 6.0-8.0 (optimum pH 7.0) and in the presence of up to 3.0% (w/v) NaCl (optimum 1%, w/v). Ubiquinone-10 was the only respiratory quinone type. Polar lipids contained diphosphatidylglycerol, phosphatidylmehtylethanolamine, phosphatidylglycerol, phosphatidylcholine and an unidentified aminolipid. The major fatty acids were detected as summed feature 8 (C-18:1 omega 7c or C-18:1 omega 6c), summed feature 3 (C-16:1 omega 7c or C-16:1 omega 6c) and C-18:1 2OH. The genomic DNA G + C content was 68.7%. The ANI values were 94.3%, 93.3% and 93.6% between Azospirillum baldaniorum Sp245(T), Azospirillum brasilense ATCC 49958(T), Azospirillum formosense CC-Nfb-7(T) and strain W712(T), respectively, which were lower than the prokaryotic species delineation threshold of 95.0-96.0%. The digital DNA-DNA hybridization values between A. baldaniorum Sp245(T), A. brasilense ATCC 49958(T), A. formosense CC-Nfb-7(T) and strain W712(T) indicated that the candidate represents a novel genomic species. According to the phenotypic and genotypic characteristics, we propose that strain W712(T) warrants the assignment to a novel species, for which the name Azospirillum tabaci sp. nov. (type strain W712(T) = CGMCC 1.18567(T) = KCTC 82186(T)) is proposed.

Automated summary

Strain W712(T) was isolated from rhizosphere soil of Nicotiana tabacum L. collected from Kunming, south-west China. Based on its phenotypic and genotypic characteristics, it represents a novel genomic species, named Azospirillum tabaci sp. nov.