Extraction and impact factors on biological activity of crude toxin produced by Fusarium heterosporum

The biological activity and its stability of crude toxin produced by Fusarium heterosporum were assayed with leaf disk of Alternanthera philoxeroides for identifying the toxin extraction method and impact factors on bioactivity of toxin.The results indicated that the highest bioactivity was from crude toxin,which was harvested by both n-butanol extraction method and active carbon absorption method.The disease index of leaf disk exposed to crude toxin reached 78.57% and 76.19% respectively.The lowest was the method of petroleum ether.The disease index of leaf disk of A.philoxeroide exposed to crude toxin concentration of 2.0-5.0 g·L-1 was from 82.38% to 83.81%,and its concentration was less than 2.0 g·L-1.The results of series experiments on impact factors on bioactivity of crude toxin showed that no obvious influence of the storage time,temperature,light time on the stability of crude toxin bioactivity was found.And the bioactivity of crude toxin was not significant different in the solution pH 3.0-11.0 excluding the influence from background pH of the solution.