A Gram-stain-positive, aerobic actinobacterium, designated strain NEAU-24T, was isolated from saline-alkali soil collected from Daqing City, Heilongjiang Province, PR China. Strain NEAU-24T was found to produce abundant substrate mycelia but no aerial hyphae. The substrate mycelia formed irregular pseudosporangia consisting of nuciform spores, and the surface of the spores was smooth. 16S rRNA gene sequence analysis showed that strain NEAU-24T clustered with Pseudosporangium ferrugineum 3-44-a(19)T, Couchioplanes caeruleus subsp. azureus DSM 44103T and C. caeruleus subsp. caeruleus DSM 43634T within the family Micromonosporaceae and was most closely related to P. ferrugineum 3-44-a(19)T (99.17 %). The strain contained meso-diaminopimelic acid as the cell-wall diamino acid and MK-9(H6) as the menaquinone. The whole cell sugar profile consisted of glucose, galactose, xylose and arabinose. The polar lipids were diphosphatidylglycerol, phosphatidylethanolamine, an unidentified phospholipid, phosphatidylinositol and an unidentified lipid. The major fatty acids were summarized as C16 : 0, C15 : 0, C17 : 0, iso-C16 : 0 and iso-C17 : 0. The low digital DNA-DNA hybridization and average nucleotide identity values could differentiate strain NEAU-24T from its related type strains. The phenotypic, genetic and chemotaxonomic data also indicated that strain NEAU-24T occupied a branch separated from those of known genera in the family Micromonosporaceae. In addition, genomic analysis confirmed that strain NEAU-24T had the potential to produce chitinase. Therefore, strain NEAU-24T represents a novel species of a new genus and species in the family Micromonosporaceae, for which the name Nucisporomicrobium flavum gen. nov., sp. nov. is proposed. The type strain of Nucisporomicrobium flavum is NEAU-24T (=CCTCC AA 2020016T=JCM 33973T).
Keywords: 16S rRNA gene; Nucisporomicrobium flavum gen. nov., sp. nov.; genome; polyphasic approach; saline-alkali soil.