Matsumoto_2013_Int.J.Syst.Evol.Microbiol_63_3404

Bacterial strains YM16-303(T) and YM16-304(T) were isolated from a sample of seashore sand using a medium with an artificial seawater base. Both isolates grew slowly on marine agar, and were found to be Gram-reaction-positive, aerobic, non-motile and rod-shaped. The cell-wall peptidoglycan contained ll-diaminopimelic acid, glycine, alanine and hydroxyglutamic acid, and the acyl type of the muramic acid was glycolyl. The predominant menaquinone was MK-9(H8). The 16S rRNA gene sequences of strains YM16-303(T) and YM16-304(T) were most similar to that of Ilumatobacter fluminis YM22-133(T), and phylogenetic analyses also indicated that they belong to the genus Ilumatobacter. Ilumatobacter fluminis YM22-133(T) and strains YM16-303(T) and YM16-304(T) should be classified as distinct species in the genus Ilumatobacter, however, since the 16S rRNA gene sequence similarity between them was low and the major cellular fatty acids and some physiological properties were different. Moreover, average nucleotide identity and maximal unique exact matches index values also supported the conclusion that they represent different species. On the basis of the above analyses, two novel species, Ilumatobacter nonamiense sp. nov. (type strain YM16-303(T) = NBRC 109120(T) = KCTC 29139(T)) and Ilumatobacter coccineum sp. nov. (type strain YM16-304(T) = NBRC 103263(T) = KCTC 29153(T)), are proposed. The order Acidimicrobiales, which contains the genus Ilumatobacter, currently includes six genera and only six species, and they are phylogenetically very far from each other. Phylogenetic analyses revealed that strains YM16-303(T) and YM16-304(T) clustered with closely related uncultured actinobacteria but not Ilumatobacter fluminis YM22-133(T), suggesting that many uncultured bacteria related to these isolates exist in the environment. This is the first report on interspecies relationships in the order Acidimicrobiales.