| Alternaria zinniae is a natural pathogen to Xanthium sibiricum, one of the worst weeds in the world. The phytotoxin produced by the fungus is the main factor that can cause the disease on Xanthium sibiricum and Zinniae elegans, Eupatoriun adenophorum, Solidago canadensis, Conyza canadensis and other weeds in the field, garden and lawn. The deep-fermentation condition, mass-production technique, abstraction procedure and pathogenic mechanism were studied, and it's the potential of using metablite of this fungus as microbial-product herbicide that was evaluated. By way of isolation and purification of the phytotoxin using modern organic analysis technics, its metabolite was obtained and its chemical structure was identified.The experiments of toxin-producing capability of the fungi under different carbon, nitrogen nutrition and environmental cultural condition were conducted. The optimal cultural conditions for producing phytotoxin were temperature 25℃, pH6.5, cultured period 9-12 days and enough darkness. The oxygen amount, rotation rate and cultural volumn were set up, based on which the culture medium was improved. The gradual addition of C and N nutrition could decrease the amount of cultural material while promoting phytotoxin-producing capability. At last, the primary exploration was studied by way of 20L fermentation device.Three different extraction methods of direct extraction, concentrating extraction by Microreticular resin, concentrating extraction by Microreticular resin+ organic solvent extraction were compared using ligroine, dichloroethane, chloroform, ethyl ethanoate, n butoxide, Diethyl ether different solvents with different polarity properties. The results showed that the preferable method was concentrating extraction by Microreticular resin + organic-solvent-extraction and the best efficient solvent was n butoxide, by which the extraction ratio could reach 89.7%. The extraction procedure was using the concentrating... |
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