Description of Patulibacter americanus sp. nov., isolated from biological soil crusts, emended description of the genus Patulibacter Takahashi et al. 2006 and proposal of Solirubrobacterales ord. nov. and Thermoleophilales ord. nov.

Abstract

Two bacterial strains, CP153-3 and CP177-2T, were isolated from biological soil crusts on the Colorado Plateau, USA, and assigned to the genus Patulibacter, according to 16S rRNA gene sequence analysis and phenotypic characteristics. The strains were Gram-positive, aerobic and psychrotolerant and showed positive catalase and negative oxidase reactions. Cells were motile in young cultures, motility consisting of subtle jerking motions, but no flagella could be detected. The strains shared high 16S rRNA gene sequence similarity (99.7 %) and DNA-DNA relatedness (99 %). They contained meso-diaminopimelic acid in the cell wall, the major menaquinone was MK-7(H2) and the predominant fatty acids were C(18 : 1)omega9c and iso-C(15 : 0). A low DNA-DNA hybridization value of 20 % with the type strain of the type species of the genus Patulibacter, Patulibacter minatonensis, as well as phenotypic differences, indicated that the isolates belong to a novel species, for which the name Patulibacter americanus sp. nov. is proposed. Strain CP177-2T (=ATCC BAA-1038(T) =DSM 16676T) was chosen as the type strain. An emended description of the genus Patulibacter is also presented. Further, two new orders are created to accommodate several families previously classified in the order Rubrobacterales Rainey et al. 1997. The first, Solirubrobacterales ord. nov., encompasses the families Solirubrobacteraceae, Conexibacteraceae and Patulibacteraceae, and the second, Thermoleophilales ord. nov., includes the family Thermoleophilaceae.