Taxonomy of the Streptomyces torulosus strain exhibiting potential for biological control

Abstract:

The actinomycete strain SCY311, which exhibited antifungal activity against various plant pathogenic fungi, was isolated from the soil samples collected from Fenghuang Mountain in Henan province in China. Identification of strain SCY311 was conducted by the methods of traditional and molecular biological taxonomy, including determination of morphological characteristics, cultural characteristics, physiological and biochemical properties, cell wall components and 16S rRNA sequences analysis. Results showed that strain SCY311 grew well on Gause′s synthetic agar plate. The color of substrate mycelium appeared brown, while that of aerial mycelium went from gray to mouse gray. The strain SCY311 neither produced the soluble pigment nor exhibited hygroscopicity. Spores were arranged in coil chains and the branched spore chains formed open or closed spirals. Spores were oval or columned in ship and the spore wall ornamentation category was knobby. Physiological properties and cultural characteristics of the strain SCY311 on the ISP media were in close agreement with that of the Streptomyces torulosus. The 16S rRNA gene sequence of strain SCY311 showed 99.9% similarity to that of S. torulosus. Based on the results above, the strain SCY311 was identified as S. torulosus.