Herbidospora solisilvae sp. nov., a novel cellulose-degrading actinobacterium isolated from forest soil

An aerobic, non-motile, Gram-stain positive, cellulose-degrading actinobacterium, designated strain NEAU-GS84^T, was isolated from a forest soil sample collected from Linchun Ridge Forest Park in Sanya, Hainan Province, China, and characterized using a polyphasic approach. Morphological and chemotaxonomic characteristics indicated that strain NEAU-GS84^T could belong to the genus Herbidospora. The 16S rRNA gene sequence analysis indeed confirmed that strain NEAU-GS84^T belonged to the genus Herbidospora and was most closely related to Herbidospora yilanensis JCM 18062^T (99.2% 16S rRNA gene sequence similarity) and Herbidospora galbida NEAU-GS14^T (99.0%). The cell wall of strain NEAU-GS84^T contained meso-diaminopimelic acid as the major diamino acid and the whole-cell hydrolysates mainly contained glucose, madurose and ribose. The major polar lipids were diphosphatidylglycerol, phosphatidylmethylethanolamine, phosphatidylethanolamine, hydroxyphosphatidylethanolamin, phosphoglycolipids, two phosphatidylinositol mannosides and one unidentified phospholipid. The predominant menaquinone was MK-10(H₄). Major fatty acids were 10-methly C_17:0, C_17:0 and iso-C_16:0. These chemotaxonomic data substantiated the affiliation of strain NEAU-GS84^T to the genus Herbidospora. The DNA G+C content was 70.7 mol%. The genome size of strain NEAU-GS84^T is about 8.37 Mb and contained 41 cellulose-binding domain synthesis genes, 13 β-glucosidase synthesis genes, 6 endoglucanase synthesis genes and 9 xylanase synthesis genes. Based on digital DNA-DNA hybridization and average nucleotide identity values, the new strain NEAU-GS84^T could be differentiated from its closest relatives. Therefore, the strain represents a novel species of the genus Herbidospora, for which the name Herbidospora solisilvae sp. nov. is proposed. The type strain is NEAU-GS84^T (= CCTCC AA 2018041^T = JCM 33460^T).