Luteipulveratus flavus sp. nov. isolated from two lichen species

Two novel strains, YIM 133132T and YIM 133296, were isolated from lichen samples collected from Yunnan Province, Southwest PR China. YIM 133132T and YIM 133296 are aerobic, Gram-staining-positive, non-motile actinomycetes. They are also catalase-positive and oxidase-negative, and YIM 133132T formed flat yellowish colonies that were relatively dry on YIM38 agar medium. Flat yellowish colonies of YIM 133296 were also observed on YIM38 agar medium. YIM 133132T grew at 25-35 °C (optimum 25-30 °C), pH 6.0-9.0 (optimum pH 7.0) and in the presence of 0-8% (w/v) NaCl. Phylogenetic analysis based on 16S rRNA gene sequences revealed that strains YIM 133132T and YIM 133296 represented members of the genus Luteipulveratus and exhibited high sequence similarity (96.93%) with Luteipulveratus halotolerans C296001T. The genomic DNA G+C content of both strains was 71.8%. The DNA-DNA hybridisation (dDDH) values between YIM 133132T and YIM 133296 were 85.1%, and the DNA-DNA hybridisation value between YIM 133132T and YIM 133296 and L. halotolerans C296001T was 23.4%. On the basis of the draft genome sequences, the average nucleotide identity (ANI) between strains YIM 133132T and YIM 133296 and L. halotolerans C296001T was 80.8%. The major menaquinones that were identified were MK-8(H4), MK-9 and MK-8(H2). The polar lipids were diphosphatidylglycerol and phosphatidylinositol. On the basis of the morphological, physiological, biochemical, genomic, phylogenetic and chemotaxonomic characteristics, strains YIM 133132T and YIM 133296 can be clearly distinguished from L. halotolerans C296001T, and the two strains represent a novel species for which the name L. flavus sp. nov. is proposed. The type strain is YIM 133132T (CGMCC= 1.61357T and KCTC= 49824T).

Leekyejoonella antrihumi gen. nov., sp. nov., a new member of the family Dermacoccaceae isolated from a cave soil

A novel Gram-stain-positive, actinobacterial strain, designated C5-26^T, was isolated from soil from a natural cave in Jeju, Republic of Korea, and its taxonomic position was investigated using a polyphasic approach. The organism was aerobic, and cells were non-spore-forming, non-motile cocci that occurred singly, in pairs, in triplets, in tetrads, in short chains or in irregular clusters. Colonies of the cells were circular, convex, entire and white. The peptidoglycan type was A4α with an l-Ser-d-Asp interpeptide bridge. The whole-cell sugars comprised glucose, rhamnose, mannose, arabinose, galactose and ribose. The major menaquinone was MK-8(H₄). The polar lipids contained diphosphatidylglycerol, phosphatidylglycerol, phosphatidylinositol and an unidentified phospholipid. The major fatty acids were iso-C_16 : 0 and iso-C_16 : 1 h. The size of the draft genome was 5.32 Mbp with depth of coverage of 161×. The G+C content of the genomic DNA was 67.1 mol%. Phylogenetic analyses based on 16S rRNA gene sequences showed that the novel isolate belonged to the family Dermacoccaceae and formed a distinct subcluster at the base of the radiation of the genus Luteipulveratus. Highest sequence similarities of the novel isolate were found to the type strains of Luteipulveratus halotolerans (96.2 %), Branchiibius hedensis (95.4 %), Luteipulveratus mongoliensis (95.4 %) and Branchiibius cervicis (95.3 %). The whole genome-based phylogeny supported the novelty of the isolate at the genus level in the family Dermacoccaceae. On the basis of data from this polyphasic study, strain C5-26^T (=KCTC 39632^T=DSM 108676^T) represents a novel species of a new genus in the family Dermacoccaceae, for which the name Leekyejoonella antrihumi gen. nov., sp. nov. is proposed.

Genome-Based Taxonomic Classification of the Phylum Actinobacteria

The application of phylogenetic taxonomic procedures led to improvements in the classification of bacteria assigned to the phylum Actinobacteria but even so there remains a need to further clarify relationships within a taxon that encompasses organisms of agricultural, biotechnological, clinical, and ecological importance. Classification of the morphologically diverse bacteria belonging to this large phylum based on a limited number of features has proved to be difficult, not least when taxonomic decisions rested heavily on interpretation of poorly resolved 16S rRNA gene trees. Here, draft genome sequences of a large collection of actinobacterial type strains were used to infer phylogenetic trees from genome-scale data using principles drawn from phylogenetic systematics. The majority of taxa were found to be monophyletic but several orders, families, and genera, as well as many species and a few subspecies were shown to be in need of revision leading to proposals for the recognition of 2 orders, 10 families, and 17 genera, as well as the transfer of over 100 species to other genera. In addition, emended descriptions are given for many species mainly involving the addition of data on genome size and DNA G+C content, the former can be considered to be a valuable taxonomic marker in actinobacterial systematics. Many of the incongruities detected when the results of the present study were compared with existing classifications had been recognized from 16S rRNA gene trees though whole-genome phylogenies proved to be much better resolved. The few significant incongruities found between 16S/23S rRNA and whole genome trees underline the pitfalls inherent in phylogenies based upon single gene sequences. Similarly good congruence was found between the discontinuous distribution of phenotypic properties and taxa delineated in the phylogenetic trees though diverse non-monophyletic taxa appeared to be based on the use of plesiomorphic character states as diagnostic features.