Description of Jidongwangia harbinensis gen. nov. sp. nov

Phylogenomic analyses of the genus Actinoplanes: description of four novel genera

The genus Actinoplanes comprises 57 species (in February 2024) that are important components of ecosystems and are widely used in biotechnology, especially pharmaceuticals. Phylogenetic analysis of the family Micromonosporaceae (based on the 16S rRNA gene sequence) allowed us to group members of different genera into separate clades; however, the genus Actinoplanes was divided into three separate clades. Such phylogenetic heterogeneity could be due to the limitations of 16S rRNA gene analysis. In response to this heterogeneity, genomic phylogeny was performed. Phylogenomic reconstruction based on 324 single-copy orthologous genes allowed us to divide the genus Actinoplanes first into four clades and then, based on average nucleotide identity analysis, into five clades. Finally, chemotaxonomic analysis of each clade confirmed each clade's distinctiveness and the necessity to reclassify the genus Actinoplanes. The obtained data allowed us to divide the genus Actinoplanes into five genera: Actinoplanes, Paractinoplanes, Winogradskya, Symbioplanes and Amorphoplanes.

Speluncibacter jeojiensis gen. nov. sp. nov., a novel bacterium of the order Mycobacteriales isolated from a cave and a proposal of Speluncibacteraceae fam. nov

Two Gram-stain-positive, aerobic, non-spore-forming, non-motile, irregular rod-shaped actinobacteria, designated as D2-41T and D3-21, were isolated from soil samples collected in a natural cave in Jeju, Republic of Korea. Both of the isolates were shown to share 100 % 16S rRNA sequence identity. The cell wall contained meso-diaminopimelic acid, arabinose and galactose. The predominant menaquinone was MK-8(H2). The polar lipids contained phosphatidylethanolamine, phosphatidylglycerol, phosphatidylinositol, phosphatidylinositol mannoside, an unidentified aminolipid, an unidentified aminoglycolipid, an unidentified phospholipid and two unidentified lipids. The predominant fatty acids were C16 : 0 and summed feature 3 (C16 : 1  ω7c and/or iso-C15 : 0 2-OH). Mycolic acids of C30-C38 were present. The 16S rRNA gene trees showed that the organisms occupied a distinct position remotely located from recognized genera within the order Mycobacteriales, albeit with the 16S rRNA gene similarities of 97.0-97.1 % with Rhodococcus olei, Rhodococcus rhodnii and Rhodococcus triatomae. The genome sizes and DNA G+C contents of strains D2-41T and D3-21 were 4.77-4.88 Mbp and 69.8 mol%, respectively. Both of the isolates shared an average nucleotide identity of 99.4 % and digital DNA-DNA hybridization of 95.2 % to each other, revealing that strains D2-41T and D3-21 belonged to the same species. In the core genome-based phylogenomic tree, both of the isolates were found to be closely associated with members of the genus Tomitella. However, strains D2-41T and D3-21 revealed the highest amino acid identity values (mean 66.5 %, range 66.2-67.0 % with the genus Prescottella of the family Nocardiaceae, followed by the genus Tomitella (mean 64.1 %, range 63.6-64.7 %) of the family Tomitellaceae. Based on the combined data obtained here, the novel isolates belong to a new genus of the new family for which the name Speluncibacter jeojiensis gen. nov. sp. nov. is proposed, with Speluncibacteraceae fam. nov. The type strain is strain D2-41T (=KACC 17930T=DSM 101875T).