sp. nov., a novel cellulase-producing actinobacterium isolated from coconut palm rhizosphere soil.

A novel cellulase-producing actinomycete, designated strain NEAU-H7, was isolated from coconut palm rhizosphere soil collected from Wenchang City, Hainan Province, PR China. A polyphasic taxonomic study was carried out to establish the status of this strain. Results of 16S rRNA gene sequence analysis indicated that strain NEAU-H7 belonged to the genus , with highest similarity to NEAU-M9 (99.2 % 16S rRNA gene sequence similarity). The diagnostic sugars in cell hydrolysates were determined to be ribose, galactose and mannose. The major fatty acids (>10%) were C, C 9 and C. The predominant menaquinones were identified as MK-9(H) and MK-9(H). The major polar lipids were phosphatidylethanolamine, phosphatidylinositol and two phosphatidylinositol mannosides. The amino acid of the cell-wall peptidoglycan was determined to be -diaminopimelic acid. The DNA G+C content was 71.2 mol%. Phylogenetic analysis using 16S rRNA gene sequences showed that strain NEAU-H7 formed a stable phyletic line with NEAU-M9. However, whole-genome phylogeny showed strain NEAU-H7 formed a stable phyletic line with NEAU-M9 (99.2%), DSM 43148 (98.6%), DSM 44859 (98.3%) and DSM 43150 (97.6%). The digital DNA-DNA hybridization (dDDH) results between them were 53.6 (50.9-56.2), 54.1 (51.3-56.9), 53.1 (50.3-55.9) and 52.9 % (50.1-55.6 %), and whole-genome average nucleotide identity (ANI) values between them were 93.7, 93.6, 93.5 and 93.5 %. The low dDDH and ANI values demonstrated that strain NEAU-H7 could be distinguished from its reference strains. Moreover, genomic analysis indicated that the strain NEAU-H7 had the potential to decompose cellulose and produce bioactive compounds. On the basis of morphological, chemotaxonomic and phylogenetic characteristics, strain NEAU-H7 is proposed to represent a novel species of the genus , with the name sp. nov. The type strain is NEAU-H7 (=CCTCC AA 2020034=DSM 112042).