Amycolatopsis melonis sp. nov., a novel protease-producing and cellulose-degrading actinobacterium isolated from soil.

Abstract

A novel protease-producing and cellulose-degrading actinobacterium, designated strain NEAU-NG30^T, was isolated from a melon rhizosphere soil sample collected in Harbin, Heilongjiang Province, China, and established its status using a polyphasic taxonomic study. Phylogenetic analysis based on 16S rRNA gene sequences revealed that strain NEAU-NG30^T was closely related to Amycolatopsis bullii DSM 45802^T (98.7%) and Amycolatopsis vancoresmycina DSM 44592^T (98.3%). The phospholipid profile contained diphosphatidylglycerol, phosphatidyl methylethanolamine, phosphatidylethanolamine and phosphatidylinositol. The diagnostic sugars in cell hydrolysates were determined to be galactose and arabinose. Cell walls contained meso-diaminopimelic acid as the diagnostic diamino acid. The predominant menaquinone was MK-9(H₄). The major fatty acids were iso-C_15:0 and iso-C_16:0. Meanwhile, genome analysis of sequences revealed a genome size of 9 338 250 bp and a DNA G+C content of 71.6%. In addition, the average nucleotide identity values and the level of digital DNA-DNA hybridization between strain NEAU-NG30^T and its reference strains fall below the thresholds typically used for delineating prokaryote species. According to phenotypic, chemotaxonomic and genotypic studies, it is indicated that strain NEAU-NG30^T is considered to be a novel species of the genus Amycolatopsis, for which the name Amycolatopsis melonis sp. nov. is proposed, with NEAU-NG30^T (=MCCC 1K08677^T=JCM 35654^T) as the type strain.