Studies On Screening And Secondary Metabolite Of Antagonistic Actinomycete In Soil

The primary studies on screening of actinomycetes which metabolize the insecticidal,fungicidal and herbicidal components in soil have been carried out from May, 2002 to May,2004. Taking Gause's Synthetic medium as the separating medium, 329 strains ofactinomycetes were separated from the soil collected in 5 provinces of China.The mainresults are as follows: 1. The herbicidal activity of fermentation extracts of 329 strains were tested againstthe Amaranthus retroflexus , Polypogeon fugar. The results of bioassay showed that theherbicidal activity of fermentation products of Z40 exhibited growth inhibition .The valueof EC50 was 0.274 mg?mL-1 and 1.402mg?mL-1 against the taproot, caulis of Amaranthusretroflexus, 0.857 mg?mL-1and 0.623 mg?mL-1 against the taproot, caulis of Polypogonfugax respectively. 2. By means of mycelium growth rate , spore germination and agar diffusion method,the fermentation products of 329 strains were tested against agricultural pathogen. Theresults show that the fermentation products of Z139 had a certain degree fungicidal activity.The results of mycelium growth rate showde that the value of EC50 against Macrophomakawatsukai , Fusarium oxysporum , Fusarium solani , Bipolaria maydis and Fusariumoxysporium were 0.505 ml?L-1,1.733 mL?L-1,0.425 mL?L-1,0.979 mL?L-1 and 0.849mL?L-1 respectively. The results of spore germination proved that the value of EC50 againstAlternaria longipes , Exserohilum turcicum , Fulvia fulva and Fusarium solani were 1.333mL?L-1,1.709 mL?L-1,0.375 mL?L-1,0.445 mL?L-1 respectively. The results of pot testindicated that the fermentation products of Z139 exhibited 98.6% of protective efficacy and86.1% of therapeutic efficacy. 3. The stability of the antibiotic productivity and cultural characteristics of the strainZ139 was not altered either by serial subculture or by modifying the preservedtemperature conditions. The fungicidal substance produced by strain Z139 could sustainhigh tempreture, acid and basic condition. 4. By means of observation on substrate mycelium, aerial mycelium, spore andsporothrix, Cultural characteristics,Biochemical and physiological characteristics, Z139strain was primaryly identified as a variety of Micropolyspora rabrobranea.