Abstract:In order to confirm the potential appliance of an antagonistic actinomycetes for biocontrol of plant diseases, 42 strains of actinomycetes were isolated from rhizosphere soil of Rehminnae glutinoso through conventional methods. Agar block method was used as preliminary screening, and disk diffusion method and growth speed rate method were used as secondary screening of the inhibition effect of strain DHR11. The taxonomic identification of strain DHR11 was studied through its morphological, cultural characteristics and 16S rDNA sequence alignment. The best liquid fermentation medium screening out six media was optimized by orthogonal array experiments. Results showed that 4 strains of actinomycetes exhibited better inhibition activity to plant pathogenic fungi tested than other strains. Among these 4 strains, strain DHR11 exhibited the strongest. The biggest inhibition zone was up to 30 mm in diameter, with an inhibition rate was 52.5% on Colletotrichum gloeosporioides. Strain DHR11 had the strongest antibacterial activity after being fermented for 9 days. Liquid fermentation medium for strain DHR11 was screened out through optimization experiment, with ingredients of sucrose 15g, soluble starch 25g, soybean meal 10g, yeast extract 7.5g, K2HPO4 0.5g, tap water 1000mL, the optimal fermentation condition being initial pH 7.5, inoculum volume 15%(v/v), stirring speed 220r/min, media volume 80mL/250 mL, fermented for 9 days at 28℃. Studies on its morphology, cultural characteristics and 16S rDNA sequence showed that strain DHR11 belongs to Streptomyces galilaeus.