sp. nov., a novel cellulase-producing actinobacterium isolated from rhizosphere soil of wheat ( L.) and emended description of the genus .

A Gram-positive, cellulose-degrading actinobacterium, designed strain NEAU-YM18, was isolated from rhizosphere soil of wheat ( L.) sampled in Langfang, Hebei Province, PR China. The novel strain was characterized using a polyphasic approach. Morphological and chemotaxonomic characteristics confirmed that strain NEAU-YM18 belonged to the genus . Cells of strain NEAU-YM18 were observed to contain - and 3-hydroxy-diaminopimelic acids as diagnostic cell-wall amino acids. The acyl type of the cell-wall muramic acid was glycolyl. The whole-cell hydrolysates were xylose, glucose and ribose. The phospholipids consisted of diphosphatidylglycerol, phosphatidylethanolamine and phosphatidylinositol. The major fatty acids were iso-C, iso-C, C 9 and summed feature 5 (anteiso-C/C 6,9). The menaquinones were MK-9(H), MK-9(H) and MK-9(H). The DNA G+C content was 71.1 %. The results of 16S rRNA gene sequence and phylogenetic analyses indicated that strain NEAU-YM18 was closely related to 2-25(1) (98.4 % 16S rRNA gene sequence similarity), NEAU-JM1 (98.3%) and H14505 (98.3 %) and formed a branch with H14505. Furthermore, the whole genome phylogeny of strain NEAU-YM18 showed that the strain formed an independent clade. The digital DNA-DNA hybridization results between NEAU-YM18 and 2-25(1), NEAU-JM1 and H14505 were 25.0, 24.7 and 24.7 %, respectively, and the whole-genome average nucleotide identity values between them were 81.5, 81.4 and 81.4 %, respectively. These genetic results and some phenotypic characteristics could distinguish strain NEAU-YM18 from its reference strains. In addition, genomic analysis confirmed that strain NEAU-YM18 had the potential to decompose cellulose and produce bioactive compounds. Therefore, strain NEAU-YM18 represents a novel species of the genus , for which the name sp. nov. is proposed. The type strain is NEAU-YM18 (=CCTCC AA 2020040=JCM 33977).