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, 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 could belong to the genus Herbidospora. The 16S rRNA gene sequence analysis indeed confirmed that strain NEAU-GS84 belonged to the genus Herbidospora and was most closely related to Herbidospora yilanensis JCM 18062 (99.2% 16S rRNA gene sequence similarity) and Herbidospora galbida NEAU-GS14 (99.0%). The cell wall of strain NEAU-GS84 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(H). Major fatty acids were 10-methly C, C and iso-C. These chemotaxonomic data substantiated the affiliation of strain NEAU-GS84 to the genus Herbidospora. The DNA G+C content was 70.7 mol%. The genome size of strain NEAU-GS84 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 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 (= CCTCC AA 2018041 = JCM 33460).