Proposal of Novosphingobium rhizosphaerae sp. nov., isolated from the rhizosphere.

A yellow, Gram-stain-negative, rod-shaped, non-spore-forming bacterium (strain JM-1(T)) was isolated from the rhizosphere of a field-grown Zea mays plant in Auburn, AL, USA. 16S rRNA gene sequence analysis of strain JM-1(T) showed high sequence similarity to the type strains of Novosphingobium capsulatum (98.9%), Novosphingobium aromaticivorans (97.4%), Novosphingobium subterraneum (97.3%) and Novosphingobium taihuense (97.1%); sequence similarities to all other type strains of species of the genus Novosphingobium were below 97.0%. DNA-DNA hybridizations of strain JM-1(T) and N. capsulatum DSM 30196(T), N. aromaticivorans SMCC F199(T) and N. subterraneum SMCC B0478(T) showed low similarity values of 33% (reciprocal: 21%), 14% (reciprocal 16%) and 36% (reciprocal 38%), respectively. Ubiquinone Q-10 was detected as the major respiratory quinone. The predominant fatty acid was C18:1ω7c (71.0%) and the typical 2-hydroxy fatty acid C14:0 2-OH (11.7%) was detected. The polar lipid profile contained the diagnostic lipids diphosphatidylglycerol, phosphatidylethanolamine, sphingoglycolipid and phosphatidylcholine. Characterization by 16S rRNA gene sequence analysis, physiological parameters, pigment analysis, and ubiquinone, polar lipid and fatty acid composition revealed that strain JM-1(T) represents a novel species of the genus Novosphingobium. For this species we propose the name Novosphingobium rhizosphaerae sp. nov. with the type strain JM-1(T) ( = LMG 28479(T) =CCM 8547(T)).