Evidence for a Close Phylogenetic Relationship Between Members of the Genera Frankia, Geodermatophilus, and “Blastococcus” and Emdendation of the Family Frankiaceae

Summary The phylogenetic position of two Frankia strains, isolated from two different host plants, was analyzed by reverse transcriptase sequencing and/or oligonucleotide cataloguing of their 16S ribosomal RNA. The two strains are highly related, showing a distinct relationship to Geodermatophilus obscurus and a strain of “Blastococcus” . These organisms constitute a main subline of descent within the phylogenetic radiation of the order Actinomycetales . In contrast to the present classification the genera Geodermatophilus and Dermatophilus cannot be considered members of the same family. Geodermatophilus is transferred into the family Frankiaceae for which an emended description is given.