Streptomonospora alba sp. nov., a novel halophilic actinomycete, and emended description of the genus Streptomonospora Cui et al. 2001.

Abstract

A halophilic actinomycete, strain YIM 90003(T), was isolated from a soil sample collected from Xinjiang Province, China, by using starch-casein agar with a salt concentration of 20 % (w/v), pH 7.0. The strain grew well on most media tested. No diffusible pigment was produced. Aerial mycelium and substrate mycelium were well developed on most media. The aerial mycelium formed short spore chains, bearing non-motile, straight to flexuous spores with wrinkled surfaces. The cell walls of strain YIM 90003(T) contained meso-diaminopimelic acid as the diagnostic diamino acid. Cell-wall hydrolysates contained galactose and arabinose. Menaquinone composition varied with the medium used for cell cultivation; on glucose-yeast extract medium supplemented with 10 % NaCl, the major menaquinone was MK-9(H(4)), while, on vitamin-enriched ISP 2 medium, the major menaquinones were MK-10(H(2)), MK-9(H(8)) and MK-10(H(4)). Phospholipids were phosphatidylglycerol, phosphatidylethanolamine, phosphatidylinositol, diphosphatidyl glycerol, methylphosphatidylethanolamine, phosphatidylserine, phosphatidylcholine and an unidentified phospholipid. 16S rRNA gene sequence analysis showed Streptomonospora salina as the closest phylogenetic neighbour. On the basis of these analyses, strain YIM 90003(T) is a member of the genus Streptomonospora, though its properties do not match the generic description fully with respect to the menaquinone composition and peptidoglycan amino acid. Analyses of mechanically disrupted cell walls of the type species, Streptomonospora salina DSM 44593(T), and strain YIM 90003(T), purified by tryptic digestion and subsequent SDS treatment, revealed the exclusive presence of meso-diaminopimelic acid as the diagnostic diamino acid of peptidoglycan. Thus, the genus description of Streptomonospora, indicating the presence of several amino acids usually not found in the peptidoglycan moiety, is therefore emended. DNA-DNA hybridization and comparison of physiological and chemotaxonomic characteristics demonstrated strain YIM 90003(T) to be different from Streptomonospora salina. The name Streptomonospora alba sp. nov. is proposed, with strain YIM 90003(T) (=CCTCC AA001013(T)=DSM 44588(T)) as the type strain.