Studies On The Nematicidal Bio-Active Substances From Mycelial Fungus

The fermentation process of the nematicidal bio-active substances from Syncephalastrum racemosum, primary separation and the properties of the bio-active substances were studied.By single factor and statistical analysis, the optimum medium, which is composed of sucrose 20g/L and peeled potato 200g/L with natural pH, and the optimal condition were determined. The 2×106 spores of fungus were incubated in 500ml conical flask with 100ml liquid cultural medium under 170r/min for 4 days at 26 ℃. The nematicidal rate reached above 85% in the one time diluted fermentation solution. During fermentation process on fermenter the nematicidal rate of one time diluted fermentation solution reached above 95% from 44h to 52h.The relationship between the morpha of Sr. and the nematicidal activity of the bio-active substances was studied. It was found that the pellets with diameter from 2mm to 4mm were formed under the optimal conditions. On the basis of observing The morpha of fungus under different condition was observed by the Scan Electronic Microscope (SEM). The result showed that when the pellet was too big, the filamentous were compact on the surface of pellets and hollow was formed inside because of the nutrient prohibition; when pellet was too small, the filamentous were hard and the nematicidal activity of the bio-active substances was low. Only when the pellets with diameter from 2mm to 4mm were formed, the filamentous were plump and the nematicidal activity was high. The gist of fermentation was provided by the study of the relationship between the morpha of Sr. and the nematicidal activity of the bio-active substances.Some properties of the fermentation liquid were studied. The results showed that nematicidal bio-active substances were water-solubility and steady with heat. It kept high bio-activity after being dealed with 30min in 121 ℃.The primary separation of bio-active sunstances was studied, too. It was concluded that nematicidal bio-active substances was composed of organic acids and non-acids. It was found that oxalic acid, citric acid and some acids else were metabolized by Sr. through HPLC, GC-MS. In addition, it was probably saturated and unsaturated fatty acids were metabolized, too. Primary separated by TLC and Sephadex G25, the bio-active substances were composed of compounds with amido and gluco- excepting organic acids. The purification of bio-activesubstances was necessary in the future.