Leucobacter tardus sp. nov., isolated from the phyllosphere of Solanum tuberosum L.

In the course of studying the composition of the microbial community in the phyllosphere of potato plants, a Gram-positive bacterium, strain K 70/01(T), was isolated. On the basis of 16S rRNA gene sequence analysis, it was shown that the investigated isolate represents a novel species in the genus Leucobacter; the closest phylogenetic neighbour was Leucobacter chromiireducens subsp. chromiireducens, with a sequence similarity of 96.8 % to the type strain. Chemotaxonomic characteristics supported affiliation to the genus Leucobacter. Strain K 70/01(T) displayed the diagnostic diamino acid 2,4-diaminobutyric acid in the cell-wall peptidoglycan. The major fatty acids were anteiso-C(15 : 0,) anteiso-C(17 : 0) and iso-C(16 : 0), which are typical of the genus. The quinone system consisted of the menaquinones MK-10, MK-11 and MK-9. Differences in several physiological features and the absence of the cell-wall amino acids gamma-aminobutyric acid and threonine enabled the isolate to be differentiated from all recognized Leucobacter species. Based on these phylogenetic and phenotypic results, it can be concluded that the isolate from the phyllosphere of potato plants represents a novel species, for which the name Leucobacter tardus sp. nov. is proposed. The type strain is K 70/01(T) (=DSM 19811(T) =LMG 24388(T)).