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 inv estigated. On the basis of restriction analyses of 16S rDNA, the isolates w ere divided into two genotypes. According to the 16S rDNA sequence analysis , representatives of both genotypes were related at a level of 99.2% simila rity 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 B 2 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 sp ecies are represented. Although the extensive morphological and physiologic al analyses did not reveal any differentiating feature for the genotypes, d ifferences in the presence of the cell-wall sugar mannose enabled the subgr oups 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 pre viously described species of Microbacterium on the basis of biochemical fea tures. As a result of phenotypic and phylogenetic analyses, the species Mic robacterium foliorum sp. nov., type strain P 333/02(T) (= DSM 12966(T) = LM G 19580(T)), and Microbacterium phyllosphaerae sp. nov., type strain P 389/ 06(T) (= DSM 13468(T) = LMG 19581(T)), are proposed. Furthermore, the recla ssification of Aureobacterium resistens (Funke et al. 1998) as Microbacteri um resistens (Funke et al. 1998) comb. nov. is proposed.