Screening and Identifying of Antagonistic Actinomycetes against Ralstonia Solancearum

In order to select effective antagonistic actinomycetes against Ralstonia solanacearum, we isolated 56 strains of actinomycetes from healthy tobacco rhizosphere soils. By pairing culture on plate method to screen antagonistic actinomycetes, we attained 3 strains of antagonistic actinomycetes, whose average inhibition diameters were more than 20 mm. We identified 3 strains of actinomycetes according to culture characteristics on differential culture mediums, spore and spore chain morphology, physiological and biochemical, molecular biology methods. The results showed that the 3 strains of actinomycetes were Streptomyces roseofulvus, Streptomyces olivaceoviridis and Streptomyces corchorusii. Among them, the best was S. roseofulvus, and average inhibition diameter was 54.66 mm. Average inhibition diameter of S.olivaceoviridis was 43.20 mm, and average inhibition diameter of S. corchorusii was 20.34 mm.