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 (H4, ω-cyclo). ... mehrThe 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$^{T}$).