Actinoplanes aureus sp. nov., a novel protease-producing actinobacterium isolated from soil
Abstract A novel protease-producing actinobacterium, designated strain NEAU-A11T, was isolated from soil collected from Aohan banner, Chifeng, Inner Mongolia Autonomous Region, China, and characterised using a polyphasic approach. On the basis of 16S rRNA gene sequence analysis, strain NEAU-A11T was indicated to belong to the genus Actinoplanes and was most closely related to Actinoplanes rectilineatus JCM 3194T (98.9 %). Cell walls contained meso-diaminopimelic acid as the diagnostic diamino acid and the whole-cell sugars were arabinose, xylose and glucose. The phospholipid profile contained diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylglycerol, phosphatidylinositol and two phosphatidylinositol mannosides. The predominant menaquinones were MK-9(H4), MK-9(H6) and MK-9(H8). The major fatty acids were C18:0, C16:0, C18:1 ω9c, C17:0 and C15:0. Genome sequencing revealed a genome size of 10,742,096 bp, a G + C content of 70.5 % and 9,514 protein-coding genes (CDSs), including 102 genes coding for protease. Genome mining analysis using antiSMASH 5.0 led to the identification of 20 putative gene clusters responsible for the production of diverse secondary metabolites. Phylogenetic analysis using the 16S rRNA gene sequences showed that the strain formed a stable clade with A. rectilineatus JCM 3194T in the genus Actinoplanes. However, whole-genome average nucleotide identity (ANI) value and the levels of digital DNA-DNA (dDDH) hybridization between strain NEAU- A11T and A. rectilineatus JCM 3194T was 81.1 % and 24.6 % (22.2–27.0 %), respectively. The values were well below the criteria for species delineation of 70% for dDDH and 95–96% for ANI, suggesting that the isolate differed genetically from its closely related type strain. In addition, evidences from phenotypic, chemotaxonomic and genotypic studies indicate that strain NEAU-A11T represents a novel species of the genus Actinoplanes, for which the name Actinoplanes aureus sp. nov. is proposed, with NEAU-A11T (= CCTCC AA 2019063T = JCM 33971T) as the type strain.