Cohnella capsici sp. nov., a novel nitrogen-fixing species isolated from Capsicum annuum rhizosphere soil, and emended description of Cohnella plantaginis.

Abstract

A novel bacterial strain designated YN-59(T) was isolated from Capsicum annuum rhizosphere soil in China. The isolate was found to be aerobic, Gram-positive, rod-shaped and to form ellipsoidal or oval spores positioned centrally in swollen sporangia. On the basis of 16S rRNA gene sequence analysis, the isolated strain YN-59 was determined to be related to members of genus Cohnella. High levels of 16S rRNA gene sequence similarity were found between strain YN-59 and Cohnella plantaginis DSM 25424(T) (98.5%) and Cohnella ginsengisoli DSM18997(T) (97.3%); the 16S rRNA gene sequence similarities between strain YN-59 and the other strains recognized members of the genus Cohnella were below 97%. The DNA-DNA hybridization values of strain YN-59 with C. plantaginis DSM 25424(T) and C. ginsengisoli DSM18997(T) were 44.2±8.4 and 28.8±5.8%, respectively. The DNA G+C content of strain YN-59(T) was determined to be 59.32mol%. The major isoprenoid quinone was identified as MK-7 and the predominant fatty acids as anteiso-C15:0 (45.32%), iso-C16:0 (19.19%), iso-C15:0 (9.65%) and C16:0 (8.91%). The polar lipids of strain YN-59(T) were found to consist of diphosphatidylglycerol, phosphatidylethanolamine and phosphatidylglycerol; several unidentified phospholipids were also detected. The diagnostic diamino acid in the cell wall was identified as meso-diaminopimelic. On the basis of its phenotypic and genotypic characteristics and levels of DNA-DNA hybridization, strain YN-59(T) is considered to represent a novel species of the genus Cohnella, for which the name Cohnella capsici sp. nov. (type strain YN-59(T)=CGMCC 1.12046(T)=JCM 19168(T)) is proposed.