Allostreptomyces psammosilenae gen. nov., sp. nov., an endophytic actinobacterium isolated from the roots of Psammosilene tunicoides and emended description of the family

A Gram-stain-positive actinobacterium, designated strain YIM DR4008, was isolated from the root sample of Psammosilene tunicoides collected from Lijiang, Yunnan, China. Strain YIM DR4008 could grow at temperatures ranging from 10 to 50 C (optimum 28–30 C), at pH 5.0–11.0 (optimum pH 7.0) and in the presence of up to 4% (w/v) NaCl. Sequence analysis of the 16S ribosomal RNA gene revealed that strain YIM DR4008 shared highest similarity (95.0%) with Streptomyces griseoplanus NBRC 12779 and <95% similarity with other known members of the genera Streptomyces, Kitasatospora and Streptacidiphilus. The diagnostic cell-wall diamino acid of strain YIM DR4008 was found to be LL-diaminopimelic acid. The whole-cell hydrolysates contained a major amount of galactose and mannose along with a small proportion of fucose, glucose, rhamnose and ribose. The polar lipids consisted of diphosphatidylglycerol, phosphatidylinositol mannosides and three unidentified phospholipids. The respiratory menaquinones were MK-9(H6) and MK-9(H8), while the major cellular fatty acids (>10%) were anteiso-C15 : 0, C16 : 0, iso-C16 : 0, iso-C15 : 0 and anteiso-C17 : 0. The genomic DNA G+C content was determined to be 75.3mol%. Based on the phenotypic, chemotaxonomic and molecular characteristics, strain YIM DR4008 is proposed to be recognized as a novel species of a new genus in the family Streptomycetaceae, with the name Allostreptomyces psammosilenae gen. nov., sp. nov. The type strain of the type species is YIM DR4008 (=DSM 42178=CGMCC 4.7247). An emended description of the family Streptomycetaceae is also provided. The family Streptomycetaceae was established in 1943 by Waksman and Henrici to accommodate aerobic, Grampositive, non-acid–alcohol-fast actinomycetes bearing extensively branched substrate mycelium that are rarely fragmented [1]. At the time of writing, the family consists of three genera namely Streptomyces [1], Kitasatospora [2] and Streptacidiphilus [3]. Members of this family are a hub for industrially important bioactive compounds [4], and have been isolated from various niches such as soil [5, 6], rhizosphere [7], forest soil [8], sand dune soil [9], lake [10] and marine sediment [11]. Of late, much emphasis has been given to isolate microbes residing within plant tissues due to the fact that they are a naturally rich source of genetic diversity and remain relatively unexplored [12]. During the last few years, our laboratory has been actively engaged in exploring novel endophytic bacteria including those belonging to the family Streptomycetaceae from economically important plants [13–15]. This paper reports a novel endophytic actinobacterium isolated from the roots of Psammosilene tunicoides collected from Lijiang, Yunnan, China. The strain showed phenotypic characters similar to those of the genus Streptomyces, however with low sequence similarities. Author affiliations: College of Landscape Architecture, Southwest Forestry University, Kunming 650224, PR China; Yunnan Institute of Microbiology, Yunnan University, Kunming 650091, PR China; State Key Laboratory of Biocontrol and Guangdong Provincial Key Laboratory of Plant Resources, School of Life Sciences, Sun Yat-Sen University, Guangzhou 510275, PR China. *Correspondence: Min Xiao, [email protected]; Hai-Quan Huang, [email protected]; Wen-Jun Li, [email protected]