Dactylosporangium solaniradicis sp. nov., a novel actinobacterium isolated from a root of tomato (Solanum lycopersicum L.).

Abstract

A novel actinobacterium, designated strain NEAU-FJL2(T), was isolated from a tomato root (Solanum lycopersicum L.) and characterised using a polyphasic approach. Morphological and chemotaxonomic properties of strain NEAU-FJL2(T) are consistent with the description of the genus Dactylosporangium. Finger-shaped sporangia were observed to form on short sporangiophores branching from the substrate hyphae. The cell wall peptidoglycan was found to contain meso- and 3-hydroxy-diaminopimelic acids; arabinose, mannose, rhamnose and xylose were found as whole-cell sugars. The phospholipid profile was found to consist of diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylglycerol and phosphatidylinositol. The predominant menaquinones were identified as MK-9(H8) and MK-9(H6). The major fatty acids were identified as iso-C16:0, C16:1 ω7c and iso-C15:0. Phylogenetic analysis based on 16S rRNA gene sequences demonstrated that strain NEAU-FJL2(T) belongs to the genus Dactylosporangium, with Dactylosporangium sucinum JCM 19831(T) (99.3% 16S rRNA gene sequence similarity), Dactylosporangium darangshiense JCM 17441(T) (99.2%), Dactylosporangium fulvum JCM 5631(T) (98.9%) and Dactylosporangium roseum JCM 3364(T) (98.8%) as the nearest phylogenetic relatives. However, a combination of DNA-DNA hybridization results and some phenotypic characteristics demonstrated that strain NEAU-FJL2(T) can be distinguished from them. Consequently, it is proposed that strain NEAU-FJL2(T) represents a novel species of the genus Dactylosporangium, for which the name Dactylosporangium solaniradicis sp. nov. is proposed. The type strain is NEAU-FJL2(T) (=CGMCC 4.7302(T)=DSM 100814(T)).