Potential of a soil-borne Streptomyces hygroscopicus for biocontrol of a anthracnose disease caused by Colletotrichum gloeosporioides in orchid

Abstract

The aims of this study are to isolate the antagonist from rhizosphere soil and evaluate its potential for biocontrol of anthracnose disease in orchid. The potential microbial antagonist, designated SRA14, was isolate and identified as Streptomyces hygroscopicus. Cell-free culture filtrates of Streptomyces hygroscopicus SRA14 inhibited the growth of Colletotrichum gloeosporioides. The percentage of growth inhibition by the stationary culture filtrate was significantly higher than that of exponential-culture filtrate. Additionally, morphological changes such as hyphal swelling and abnormal shapes were observed in fungi grown on potato dextrose agar that contained the culture filtrates. Application of culture filtrates was able to prevent the expression of anthracnose disease on orchid, indicating that disease inhibition was due to antifungal metabolites in the culture filtrates. No significantly the prevention of anthracnose development was observed in the stationary culture filtrate and mancozeb-treated leaves. Present data suggested the stationary culture filtrate of SRA14 can be used as biofungicide for control of anthracnose diseases in Dendrobium orchid. © 2008 Asian Network for Scientific Information.