The Biology Of Strain 357 For The Production Of Antagonistic Substance And The Cloning Of SHC Gene From Strain 357

Strain 357 conserved in our laboratory has antagonistic activities to some pathogenic fungi, and it can inhibit strongly the growth of Rhizoctonia solani. To find out the appropriate cultural conditions for the growth and for the maximum production of antagonistic substance by strain 357, the stains 357 was incubate in six media, i.e. KMB, LB, PDA, Davis, SMA and Danbo, the bacterial growth and the antagonistic activity were detected, respectively. The results showed that strain 357 grew best and produced the highest antagonistic activity after culture on KMB medium by using the same volume of cultured liquid. But the antagonistic activity was the greatest after cultured on Davis medium when some quantity of bacteria was used. The results also showed there was no difference on the antagonistic activity when 357 was cultured in the solid medium or liquid medium.When LB medium was added with glycerol, the antagonistic activity was increased; the antagonistic activity has no changes when KH2PO4 or MgSO4 was added. Based on the Davis medium, the effects of different C resources and N resources on the antagonistic activity produced by strain 357 were studied, the results showed that the use of C resources with the mixture of glucose and glycerol and N resources with (NH4)2SO4 could make best growth and greatest antagonistic activity.In addition, the antagonistic activities showed highest when 357 was cultured at 37℃ and pH7.5 after serial tests at various temperatures or various pH. Moreover, the antagonistic activity reached highest when 357 was cultured at the later logarithm growth period.All the studies above will be helpful for the isolation and purification of the antagonistic substance produced by B. cereus 357 in large scale in future, it will also be helpful for the continue study the factors related the growth and the antagonistic...