Agrococcus versicolor sp nov., an actinobacterium associated with the phyllosphere of potato plants

The taxonomic position of a group of actinobacterial strains isolated from the phyllosphere of potato plants was investigated by using a polyphasic approach. Although the similarity values for their 16S rRNA gene sequences suggested an intermediate position between Microbacterium and Agrococcus, the phylogenetic tree demonstrated a clear clustering of the representative strain, K 114/01(T), within the genus Agrococcus. The presence of 2,4-diaminobutyric acid as the diagnostic diamino acid in the cell-wall peptidoglycan of strain K 114/01(T) substantiated the affiliation to the genus Agrococcus. An analysis performed using matrix-assisted laser desorption ionization-time-of-flight mass spectrometry revealed highly similar spectral patterns for the isolated strains, which, together with their conformity regarding a multitude of phenotypic features, supported their affiliation to the same species. Differences in several physiological features, peptidoglycan and menaquinone composition and whole-cell fatty acid profiles enabled discrimination of the phyllosphere isolates with respect to recognized Agrococcus species. As the 16S rRNA gene sequence similarity values were below 97 %, the strains isolated from the phyllosphere of potato plants represent a novel species of the genus Agrococcus, for which the name Agrococcus versicolor sp. nov. is proposed. The type strain is K 114/01(T) (=DSM 19812(T) = LMG 24386(T)).