Pseudonocardia antarctica sp. nov. an Actinomycetes from McMurdo Dry Valleys, Antarctica

Abstract

Strain DVS 5a1 was isolated from a moraine sample from the McMurdo Dry Valleys region of Antarctica. The strain is aerobic, Gram-positive, with white aerial mycelia and brown substrate mycelia, sporulating, has meso-diaminopimelic acid, arabinose and galactose in the cell wall, MK-8 (H4) as the major menaquinone and a mol% G+C content of DNA of 71% thus confirming to the description of the genus Pseudonocardia. Phylogenetic analysis based on the 16S rRNA gene sequence analysis further confirms that DVS 5a1 which forms a robust clade with P. alni, P. compacta, P. autotrophica and P. kongjuensis is closely related to the genus Pseudonocardia and exhibits maximum similarity of 99.7% with Pseudonocardia alni. However, at whole genome level as determined by DNA-DNA hybridisation DVS 5a1 exhibits a similarity of only 50% with Pseudonocardia alni. Further, DVS 5a1 differs from Pseudonocardia alni in that it does not produce acid from D-arabinose, meso- erythritol, melizitose, sorbitol, sucrose, D-trehalose; but produces acid from D-mannitol, D-galactose, D-maltose, D-mannose, inulin, D-ribose and D-xylose. Further, compared to Pseudonocardia alni, it has two additional fatty acids namely Me-C_18:0 and Me-C_19:0 and also possesses one additional unidentified lipid. It also shows distinct differences with P. compacta, P. autotrophica and P. kongjuensis and the other species of Pseudonocardia. It is proposed to assign DVS 5a1 the status of a new species for which the name Pseudonocardia antarctica sp. nov. is suggested.