Rathayibacter tanaceti sp. nov., a Novel Actinobacterium from Tanacetum vulgare Infested by Foliar Nematode Aphelenchoides sp.

Abstract

Two novel yellow-pigmented, rod-shaped and non-motile coryneform actinobacteria, strains VKM Ac-2596T and VKM Ac-2761, were isolated from a plant Tanacetum vulgare (Asteraceae) infested by foliar nematode Aphelenchoides sp. The strains exhibited the highest 16S rRNA gene sequence similarities to Rathayibacter agropyri CA4T (99.71%), Rathayibacter rathayi DSM 7485T (99.65%) and Rathayibacter iranicus VKM Ac-1602T (99.65%). The pairwise average nucleotide identity (ANI) and digital DNA-DNA hybridization (dDDH) values between VKM Ac-2596T and VKM Ac-2671 towards the type strains of Rathayibacter species did not exceed 85.24% and 29.40%, respectively, that are well below the thresholds for species delineation. The target strains had key chemotaxonomic properties typical of the genus Rathayibacter, namely, the DAB-based peptidoglycan, rhamnose and mannose as the predominant sugars and a rhamnomannan in the cell, the major menaquinone MK-10 and fatty acids of iso-anteiso type, with a large proportion of anteiso-15:0. The strains showed clear differences from the recognized Rathayibacter species in several phenotypic characteristics, including the difference in the composition of cell wall glycopolymers. Based on the results obtained in this study and the data published previously, we provide a description of a new species, Rathayibacter tanaceti sp. nov., with DL-642T (= VKM Ac-2596T = LMG 33114T) as the type strain.