Selection And Identification Of The Antagonistic Microbes Of Ginseng Rusted Root Disease

The 135 soil samples were collected from ginseng planting fields in Ji'an, Jingyu and Fusong in Jilin province during 2004-2005. 45 strains of fungi, 67 strains of bacteria and 221 strains of actinomycetes were isolated from the soil samples, The variations of microbal populations in ginseng rhizosphere were also studied.The variations of microbal populations of different ages ginseng planting fields and different depth were mainly studied. It showed that the microbal populations were decreased with the increasing planting ages. The variations of microbal populations between 5-year planting fields and replanting fields were more significant than the variations of microbal populations between preplanting fields and 1-year planting fields. It also showed that the microbal populations were decreased with the increasing soil depth. The variations of microbal populations between 0-5 cm layers and 5-10 cm were more significant than the variations between 5-10 cm layers and 10-15 cm layers. But the same trend did not appear in the same layers of different ages planting fields.The antagonistic tests were carried out among the microbes which isolated from all the soil samples against Cylindrocarpon destructans. None of 45 strains of fungi had antagonistic effects against C. destructans. Only 2 in 67 strains of bacteria had antagonistic effects, but the effects were not stable. 11 in 221 strains of actinomycetes had antagonistic effects. Then the 11 strains of actinomycetes were cultivated in liquid medium. The antagonistic tests were done again by the liquids. At last the best antagonistic actinomycetes called JY36 were selected.The liquid culture conditions of JY 36 were primarily studied including medium, pH, temperature and times. After that the orthogonal tests were done. Eventually the optimal conditions were determined: the corn flour and bean flour medium, 30 ℃, pH 9,120h.The morphological observation and physical and biochemical characters were examined. The sequences of 16SrDNA were analysed. JY 36 had the typical morphological characters of Streptomycetes.The results of physical and biochemical characters were the gelatine liquefication, no production of H₂S, no solidification and peptonization of milk, starch hydrolyzation. It utilized D-glucose, D- xylose, D-fructose, sucrose, gossypose, inositol as carbon source.The length of 16S rDNA sequences was 1264 bp. Comparing with the high homological 50 strains of Streptomyces in GenBank, the sequences of JY36 were the same as Streptomyces prunicolor. It indicated that JY36 was S. prunicolor.