Nocardia macrotermitis sp. nov. and Nocardia aurantia sp. nov., isolated from the gut of the fungus-growing termite Macrotermes natalensis

The taxonomic positions of two novel aerobic, Gram-stain-positive Actinobacteria, designated RB20(T) and RB56(T), were determined using a polyphasic approach. Both were isolated from the fungus-farming termite Macrotermes natalensis. Results of 16S rRNA gene sequence analysis revealed that both strains are members of the genus Nocardia with the closest phylogenetic neighbours Nocardia miyunensis JCM12860(T) (98.9 %) and Nocardia nova DSM44481(T) (98.5 %) for RB20(T) and Nocardia takedensis DSM 44801(T) (98.3 %), Nocardia pseudobrasiliensis DSM 44290(T) (98.3 %) and Nocardia rayongensis JCM 19832(T) (98.2 %) for RB56(T). Digital DNA–DNA hybridization (DDH) between RB20(T) and N. miyunensis JCM12860(T) and N. nova DSM 44481(T) resulted in similarity values of 33.9 and 22.0 %, respectively. DDH between RB56(T) and N. takedensis DSM44801(T) and N. pseudobrasiliensis DSM44290(T) showed similarity values of 20.7 and 22.3 %, respectively. In addition, wet-lab DDH between RB56(T) and N. rayongensis JCM19832(T) resulted in 10.2 % (14.5 %) similarity. Both strains showed morphological and chemotaxonomic features typical for the genus Nocardia , such as the presence of meso-diaminopimelic acid (A(2)pm) within the cell wall, arabinose and galactose as major sugar components within whole cell-wall hydrolysates, the presence of mycolic acids and major phospholipids (diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylinositol), and the predominant menaquinone MK-8 (H(4), ω-cyclo). The main fatty acids for both strains were hexadecanoic acid (C(16 : 0)), 10-methyloctadecanoic acid (10-methyl C(18 : 0)) and cis-9-octadecenoic acid (C(18 : 1) ω9c). We propose two novel species within the genus Nocardia : Nocardia macrotermitis sp. nov. with the type strain RB20(T) (=VKM Ac-2841(T)=NRRL B65541(T)) and Nocardia aurantia sp. nov. with the type strain RB56(T) (=VKM Ac-2842(T)=NRRL B65542(T)).