Studies On Biological Characteristic And Control Effect Of Six Strains Of Actinomyces Against Target Pathogens

The biological characteristic and inhibiting effect of six strains of actinomyces trapped from soil and proved having strong biocontrol potential capability were studied. The conditions of fermentation were optimized and the method for rejuvenating and conserving tested actinomyces candidates were determined. Four pathogenic fungi, including Colletotrichum gloeosporioides, Trichothecium roseum Botrytis cinerea and F. oxysporum f.sp. niveum were used as target pathogens to test the antagonistic capability of six actinomyces. The result demonstrated that six organisms named SC1, SC1-1, SE2, A3, A4 and 15-3 showed significant inhibiting effect and germentation of spores of target pathogens were suppressed obviously by the fermentation filtrate of them. Mixcultured respectively with six actinomyces respectively, target pathogens were inhibited by them. Apple postharvested decay caused by B. cinerea could be inhibited effectively by the fermentation broth of six actinomyces, the inhibition rate of SC1, A3, SE2 and 15-3 surpassing 80%; and the expansion of the disease even could be impacted by the suspension of 15-3. From May to November in 2004. Field experiment to evaluate control effect of six actinomyces were done, the result having shown that fungi on surfaces of apple fruits and leaves could be controlled by strains SC1 and 15-3. Six strains of actinomyces candidates with significant biocontrol potential were tagged with antibiotics, fungicides or combination of them. The result showed that cucumber, wheat and barley plant could been colonized by strain 15-3 and the amount of strain 15-3 in root of cucumber was more than that in the other two crops. Six strains of tested actinomyces had no inhibition on germination of seeds and growth in seedling stage of cucumber, wheat, barley and soybean, and the development of tested plants could be promoted by strain 15-3. The result also showed that the surface of apple fruits covered with paper bag and leaves could be colonized by strain 15-3. Optimized conditions for fermentation of five actinomyces were ascertained .The result showed that optimized mediums for strains SC1, SC1-1, SE2, A3 and A4 were SNB, SYB, SYB, SNB and DSB respectively; pH were 7.0, 6.0, 6.7, 6.0 and 7.0;and the fittest culture time for them were 48h-72h, 72h-96h, 48h-72h, 72h-96h and 48h-72h. Exploration on rejuvenating and conserving six strains of actinomyces indicated that the growth and antagonistic capability of strain A3 were enhanced in soil with chitin.