Screening Of Antagonistic Actinomycetes Against Alternaria Solani And Study On Antifungal Actions

Tomato early blight occurred worldwide and significantly affected the quality and yield of many economically important plants. The most effective control measure was frequent application of protectant fungicides from early in the growing season. However, long-term and repeated application of synthetic pesticides for early blight control had resulted in a rapid increase in resistance, undesirable effects on non-target organisms and the intensity of public concerns about environmental and human health. Thus, there was need to discover new products that can control Alternaria solani effectively, as flexibly as possible. Soil antagonistic actinomycetes had a variety of breeds and cultivate easily, many species had the capacity to produce antibiotics and became the main subject to develop new pesticide as bio-control agent. With the objective of exploring and developing new antibiotics pesticide, 130 strains of actinomycete seaparted from Xinjiang soil samples were tested against Tomato early blight, and a systematic study on strains with high antibacterial activity had been done, the main results as follows:1,The fungicidal activities of the fermentation broths of 130 strains of actinomycete isolated from soil samples collected from Xinjiang,were evaluated by tissue culture method and potted plant method against Tomato early blight.The results showed that fermentation broths of 124 strains of actinomycetes had different levels of control effect, which were inhibited 90% by seven actinomycetes; The strain named 104-3 showed strongest inhibition effect, the control effect of fermentation production treatment and its 5 times dilute treatment reached 91.30% and 71.40%, respectively. The results of the pot experiment showed that the efficacy of 104-3 reached 72.74%, better than the others.2,The fermentation broth of actinomycete strain 104-3 had broad-spectrum, strong antibacterial activity.It had high inhibition effect rate (>90%) against E. turcicum,G. graminis,C.cinyulate,B. maydis,P. oryzaecar,V. mali when diluted by ten times. Meanwhile , it also showed strongest inhibition effect against Bacillus subtilis and Bacillus thuringiensis,the inhibition zone diameter was above 18.00 mm.3,Based on growth characteristics, the morphological characteristics, biochemical and physiological characteristics of strain 104-3, it was identified as Streptomyces flavus sp.4,Strain 104-3 was mutated by UV mutation, chemical mutation, A high producing strain named 10s-9 was obtained through the UV mutation for 10s and the inhibition effect increased 38.73% against Bacillus subtilis.5,The fermentation conditions and medium component of strain 104-3 were studied。The results were 0.5% glucose,0.2% Tryptone,0.25% Nacl,0.2%CaCO3,40% medium volume,temperature 24℃,initial pH 7.0,optimal ermentation time 72h,rotary speed 190r/m,inculation volume 8%.After optimization,the antibiotic activity of strain 104-3 improved by 8.16% and 34.14% against Alternaria solani and Bacillus subtilis,respectively.