A Gram-staining-positive actinobacterium, designated strain 1MR-8T, was isolated from the rhizoplane of ginseng and its taxonomic status was determined using a polyphasic approach. The isolate formed long chains of spores that were straight, cylindrical and smooth-surfaced. Strain 1MR-8T grew at 10–37 °C (optimum 28 °C), whilst no growth was observed at 45 °C. The pH range for growth was 4.0–11.0 (optimum pH 6.0–8.0) and the NaCl range for growth was 0–7 % (w/v) with optimum growth at 1 % (w/v). Strain 1MR-8T had cell-wall peptidoglycans based on ll-diaminopimelic acid. Glucose, mannose and ribose were the whole-cell sugars. The predominant isoprenoid quinones were MK-9 (H4), MK-9 (H6) and MK-9 (H8) and the major fatty acids were anteiso-C15 : 0, iso-C15 : 0, anteiso-C17 : 0 and iso-C16 : 0. 16S rRNA gene sequencing studies showed that the novel strain was closely related to the type strains of Streptomyces caeruleatus GIMN4T, Streptomyces curacoi NRRL B-2901T, Streptomyces capoamus JCM 4734T and Streptomyces coeruleorubidus NBRC 12761T with similarities of 98.8 %. However, DNA–DNA relatedness, as well as physiological and biochemical analyses, showed that strain 1MR-8T could be differentiated from its closest phylogenetic relatives. It is proposed that this strain should be classified as a representative of a novel species of the genus Streptomyces , with the suggested name Streptomyces panaciradicis sp. nov. The type strain is 1MR-8T ( = KACC 17632T = NBRC 109811T).
The phylogeny of the class Actinobacteria remains controversial, essentially because it is very sensitive to the choice of dataset and phylogenetic methods. We used a test proposed recently, based on complete genome data, which chooses among candidate species phylogenies based on the number of lateral gene transfers (LGT) needed to explain the diversity of histories among gene trees for a set of genomes. We used 100 completely sequenced genomes representing 35 families and 17 orders of the class Actinobacteria and evaluated eight different hypotheses for their phylogeny, including one based on a concatenate of 54 conserved proteins present in single copy in all these genomes, trees based on 16S and 23S rRNA gene sequences or their concatenation, and a tree based on the concatenation of MLSA genes (encoding AtpI, GyrA, FtsZ, SecA and DnaK). We used Prunier to infer the number of LGT in 579 proteins (different from those used to build the concatenated tree) present in at least 70 species, using the different hypothetical species trees as references. The best tree, with the lowest number of lateral transfers, was the one based on the concatenation of 54 proteins. In that tree, the orders Bifidobacteriales , Coriobacteriales , ‘Coryneb acteriales’, ‘Micromonosporales’, ‘Propionibacteriales’, ‘Pseudonocardiales’, Streptomycetales and ‘Streptosporangiales’ were recovered while the orders ‘Frankiales’ and Micrococcales were not. It is thus proposed that the order ‘Frankiales’, which has an effectively but not validly published name, be split into Frankiales ord. nov. (type family Frankiaceae ), Geodermatophilales ord. nov. ( Geodermatophilaceae ), Acidothermales ord. nov. ( Acidothermaceae ) and Nakamurellales ord. nov. ( Nakamurellaceae ). The order Micrococcales should also be split into Micrococcales (genera Kocuria , Rothia , Micrococcus , Arthrobacter , Tropheryma , Microbacterium , Leifsonia and Clavibacter ), Cellulomonales ( Beutenbergia , Cellulomonas , Xylanimonas , Jonesia and Sanguibacter ) and Brachybacteriales ( Brachybacterium ) but the formal proposal for this will have to wait until more genomes become available for a significant proportion of strains in this order.
A Gram-positive, spore-forming, rod-shaped actinomycete, designated XJ46T, was isolated from Xinjiang Uyghur Autonomous Region, China and subjected to a polyphasic taxonomic analysis. Morphological and chemotaxonomic characteristics of XJ46T were identified as being similar to those of members of the genus Prauserella . The phylogenetic tree based on 16S rRNA gene sequences showed that XJ46T shared the highest similarity (95.9 %) with Prauserella marina MS498T. Based on its phenotypic characteristics, chemotaxonomic analysis and 16S rRNA gene sequence analysis, strain XJ46T is proposed to represent a novel species of the genus Prauserella , named Prauserella shujinwangii sp. nov. The type strain is XJ46T ( = CGMCC 4.7125T = JCM 19736T).