Development of a Kribbella-specific isolation medium and description of Kribbella capetownensis sp. nov. and Kribbella speibonae sp. nov., isolated from soil.

Two actinobacterial strains were isolated from samples collected from the University of Cape Town, South Africa. A third actinobacterial strain was isolated from soil collected in the town of Stellenbosch, South Africa, using a newly-developed Kribbella-selective medium. Analysis of the 16S rRNA genes showed that the three strains belonged to the genus Kribbella. A multilocus sequence analysis using the concatenated gene sequences of the gyrB, rpoB, relA, recA and atpD genes showed that strains YM55 and SK5 were most closely related to the type strains of Kribbella sindirgiensis and Kribbella soli, while strain YM53 was most closely related to the type strain of Kribbella pittospori. Digital DNA-DNA hybridisation and Average Nucleotide Identity (ANI) analyses showed that strains YM55 and SK5 belong to the same genomic species (OrthoANI value = 98.4%), but are distinct from the genomic species represented by the type strains of K. sindirgiensis (OrthoANI values < 95.6%) and K. soli (OrthoANI values < 91.4%). Strain YM53 is distinct from the genomic species represented by the type strain of K. pittospori (OrthoANI value = 94.0%). Phenotypic comparisons showed that strains YM55 and SK5 are distinct from the type strains of K. sindirgiensis and K. soli and that strain YM53 is distinct from the type strain of K. pittospori. Strains YM53 and YM55 are thus presented as the type strains of novel species, for which the names Kribbella capetownensis sp. nov. (= DSM 29426 = NRRL B-65062) and Kribbella speibonae sp. nov. (= DSM 29425 = NRRL B-59161), respectively, are proposed.