Isolation, Screening, and Identification of Actinomycetes with Antifungaland Enzyme Activity Assays against Colletotrichum dematium ofSarcandra glabra

ABSTRACT

A serious leaf disease caused by Colletotrichum dematium was found during the cultivationof Sarcandra glabra in Jingxi, Rong’an, and Donglan Counties in Guangxi Province, whichinflicted huge losses to plant productivity. Biological control gradually became an effectivecontrol method for plant pathogens. Many studies showed that the application of actinomycetesin biological control has been effective. Therefore, it may be of great significance tostudy the application of actinomycetes on controlling the diseases caused by S. glabra.Strains of antifungal actinomycetes capable of inhibiting C. dematium were identified, isolatedand screened from healthy plants tissues and the rhizospheres in soils containing S.glabra. In this study, 15 actinomycetes strains were isolated and among these, strains JT-2F,DT-3F, and JJ-3F, appeared to show antagonistic effects against anthracnose of S. glabra.The strains JT-2F and DT-3F were isolated from soil, while JJ-3F was isolated from plantstems. The antagonism rate of strain JT-2F was 86.75%, which was the highest value amongthe three strains. Additionally, the JT-2F strain also had the strongest antagonistic activitywhen the antagonistic activities were tested against seven plant pathogens. Strain JT-2F isable to produce proteases and cellulase to degrade the protein and cellulose componentsof cell walls of C. dematium, respectively. This results in mycelia damage which leads toinhibition of the growth of C. dematium. Strain JT-2F was identified as Streptomyces tsukiyonensisbased on morphological traits and 16S rDNA sequence analysis.