The family Dietziaceae

Abstract

Members of Dietziaceae, actinomycetes characterized by the presence of mycolic acids, especially high molecular weight 3-hydroxy fatty acids substituted in the two positions with a long alkyl branch, have previously been classified in the suborder Corynebacterinae. The suborder Corynebacterinae was originally placed in the order Actinomycetales. According to Bergey's road map of the Actinobacteria, the six families Corynebacteriaeceae, Tsukumarellaceae, Mycobacteriaceae, Nocardiaceae, Segniliparaceae, and Dietziaceae were removed from the order Actinomycetales and assigned to the order Corynebacterales. The family Dietziaceae comprises solely the genus Dietzia which consists of 13 species with validly published names. The morphology and physiology of Dietzia species is similar to that of Rhodococcus equi, which in the past often led to misidentification of Dietzia strains by traditional identification techniques. Nowadays molecular based methods like 16S rRNA gene sequencing can be used to discriminate Dietzia strains from the type strain of Rhodococcus equi. This is of ecological significance, as members of Dietzia have been isolated from diverse environments including clinical specimens, which led to conclusion that Dietzia species may act as an opportunistic pathogen.