Description of Microbacterium foliorum sp nov and Microbacterium phyllosphaerae sp nov., isolated from the phyllosphere of grasses and the surface litter after mulching the sward, and reclassification of Aureobacterium resistens (Funke et al. 1998) as Microbacterium resistens comb. nov.

The taxonomic position of a group of coryneform bacteria isolated from the phyllosphere of grasses and the surface litter after sward mulching was investigated. On the basis of restriction analyses of 16S rDNA, the isolates were divided into two genotypes. According to the 16S rDNA sequence analysis, representatives of both genotypes were related at a level of 99.2% similarity and clustered within the genus Microbacterium. Chemotaxonomic features (major menaquinones MK-12, MK-11 and MK-10; predominating iso-and anteiso-branched cellular fatty acids; G+C content 64-67 mol%; peptidoglycan-type B2 beta with glycolyl residues) corresponded to this genus as well. DNA-DNA hybridization studies showed a reassociation value of less than 70% between representative strains of both subgroups, suggesting that two different species are represented. Although the extensive morphological and physiological analyses did not reveal any differentiating feature for the genotypes, differences in the presence of the cell-wall sugar mannose enabled the subgroups to be distinguished from one another. DNA-DNA hybridization with type strains of closely related Microbacterium spp. indicated that the isolates represent two individual species, which can also be differentiated from previously described species of Microbacterium on the basis of biochemical features. As a result of phenotypic and phylogenetic analyses, the species Microbacterium foliorum sp. nov., type strain P 333/02(T) (= DSM 12966(T) = LMG 19580(T)), and Microbacterium phyllosphaerae sp. nov., type strain P 389/06(T) (= DSM 13468(T) = LMG 19581(T)), are proposed. Furthermore, the reclassification of Aureobacterium resistens (Funke et al. 1998) as Microbacterium resistens (Funke et al. 1998) comb. nov. is proposed.