A new species of nitrogen-fixing bacteria, Azospirillum irakense, was found associated with roots and the rhizosphere of rice in the region of Diwaniyah (Qadisya), Iraq. The seven isolates, on which the species description is based, have vibrioid to S-shaped cells with one polar flagellum in liquid medium. Additional lateral flagella are seen on cells grown on nutrient agar. Poly-beta-hydroxybutyrate granules are present in cells. Nitrogen fixation occurs in microaerobic conditions. The phenotypic characters were found to be very close to those of A. amazonense with the following differences: growth occurred in the presence of 3% NaCl, and at pH 5.5 and 8.5, myo-inositol was not utilized as sole source of carbon and energy and pectin was slowly (6 to 9 days) hydrolysed. The seven studied strains formed a DNA-relatedness group distinct from other Azospirillum and Herbaspirillum species. The G + C content of the DNA was 64 to 67 mol %. The type strain is KBC1 (CIP 103311).

A taxonomic study was carried out on a novel aerobic bacterial strain (designated CC-LY736(T)) isolated from a fermentor in Taiwan. Cells of strain CC-LY736(T) were Gram-stain negative, spiral-shaped and motile by means of a monopolar flagellum. Strain CC-LY736(T) shared the greatest degree of 16S rRNA gene sequence similarity to Azospirillum irakense DSM 11586(T) (97.2 %), Rhodocista centenaria JCM 21060(T) (96.3 %) and Rhodocista pekingensis JCM 11669(T) (96.1 %). The major fatty acids were C16:0, C16:1 �s5c, C19:0 cyclo �s8c, C18:1 �s7c/C18:1 �s6c, C16:0 3-OH and C18:1 2-OH. The predominant polar lipids included phosphatidylcholine, phosphatidylglycerol, diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylmethylethanolamine, phosphatidyldimethylethanolamine and two unidentified glycolipids. The common major respiratory quinone was ubiquinone Q-10 and predominant polyamines were sym-homospermidine and putrescine. The DNA G+C content of strain CC-LY736(T) was 67.6 �� 0.1 mol %. During phylogenetic analysis, strain CC-LY736(T) formed a unique phyletic lineage associated with Rhodocista species. However, the combination of genetic, chemotaxonomic and physiological data clearly indicated that strain CC-LY736(T) was a novel representative of the family Rhodospirillaceae. Based on the polyphasic comparison, the name Niveispirillum fermenti gen. nov., sp. nov. is proposed; the type strain of the type species is CC-LY736(T) (= BCRC 80504(T) = LMG 27263(T)). In addition, the reclassifications of Azospirillum irakense as Niveispirillum irakense comb. nov. (type strain KBC1(T) = ATCC 51182(T) = BCRC 15764(T) = CIP 103311(T)), and Azospirillum amazonense as Nitrospirillum amazonense gen. nov., sp. nov. (type strain Am14(T) = ATCC 35119(T) = BCRC 14279(T) = DSM 3787(T)) are proposed based on the polyphasic taxonomic data obtained in this study.