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

ABSTRACT: 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 (A₂pm) 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). 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).

SUBMITTER: Benndorf R 

PROVIDER: S-EPMC7660896 | biostudies-literature | 2020 Oct

REPOSITORIES: biostudies-literature