Actinomycetospora callitridis sp. nov., an endophytic actinobacterium isolated from the surface-sterilised root of an Australian native pine tree.

An endophytic actinobacterium, strain CAP 335, was isolated from a root sample of a native pine tree growing on the Bedford Park campus of Flinders University, Adelaide, South Australia. The result of a polyphasic study showed that this strain was identified as a new member of the genus Actinomycetospora. This strain was observed to be a Gram stain-positive, aerobic actinobacterium with well-developed substrate mycelia and to form short chains of spores. Actinomycetospora chibensis TT04-21 and Actinomycetospora straminea IY07-55 were found to be close phylogenetic neighbours, each sharing 99.1% 16S rRNA gene similarity. Chemotaxonomic data including major fatty acids, cell wall components and major menaquinones confirmed the affiliation of strain CAP 335 to the genus Actinomycetospora. The phylogenetic analysis, physiological and biochemical studies and DNA-DNA hybridization, allowed the genotypic and phenotypic differentiation of strain CAP 335 and the closely related species with valid names. The name proposed for the new species is Actinomycetospora callitridis sp. nov. The type strain is CAP 335 (= DSM 101857 = NRRL B-65350).