Aritifical Cultivation Of Cordyceps Militaris On Bombyx Mori And The Analysis Of ITS DNA Sequence

Cordyceps militaris is also called north Cordyceps sinensis or north Cordyceps. Cordyceps militaris is one of precious officinal fungi in our country, of which medicinal value is similar to Cordyceps sinensis that are well known both at home and abroad. Its wild resource is reducing day by day that makes the price of Cordyceps higher than it was. Therefor, it is in a good position in the international market. Presently, Cordyceps militaris's biological characters, artifical cultivation and value of application have been researched deeply at home and abroad. There are a lot of reports about the different ways of infecting Bombyx mori larvae with Cordyceps militaris to cultivate sporophore. However, the output and stability of fruit body is lower. So, in this paper the author did some studies as following:1.Experiments on artifical culture medium: firstly, active culture medium would be screened out for the growth of hypha in order to enrich PDA culture medium. Then through doing the experiments with different strains on artifical culture medium, we would find the better condition that is suit for its growth.2.Experiments on the infection of Bombyx mori with Cordyceps militaryis: through infecting fifth instar Bombyx mori larvae, surface sterilization and infection method and spores liquid injection method were screened out. It proved that this method is the most effective. Meanwhile, Bombyx mori pupae have been also infected. Then the optimal condition could be found. Consequently, the strain 04718 was sceened out by infecting Bombyx mori larvae and pupae.3. Rejuvenation experiment of degenerative strains and genealogy analysis based on ITS DNA of tested strains: Degenerative phenomenon of strains often appears during the process of artifical cultivation of Cordyceps militaris. To deal with this problem, on one hand, we have done some rejuvenation experiments of tested strains and found the fine method is worm body inoculation. On the other hand, nucleic acid sequence analysis methods were applied in the experiment. ITS regions of 16 tested strains were amplified and sequenced. System analysis indicated that a great change in the level of molecule was caused between rejuvenative strains and degenerative strains. Rejuvenative strains and undegenerative strains have a great comparability after rejuvenation. Kindredship and system evolvement among the tested strains were analyzed by phylogenesis tree.