Dynamic spore outputs and antibiotic activities of asexual fungi (strain CY-8202) isolated from Cordyceps sinensis / 中草药

ABSTRACT

Object To study the growth speed and dynamic spore production of CY-8202, which is an asexual strain of entomopathogenic fungi isloated from Cordyceps sinensis (Berk.) Sacc., to explore the method of artificial culture of CY-8208 strain, to assay its antibiotic activity and spectrem and to provide the experimental basis for studies of its active components. Methods Variations in colony diameter of the cordyceps hypha cultured on the fungi media were measured. The spore-count was used to determine the dynamic colony spore outputs of the hypha on several fungi media and water agar. The agar-piece method was used to test its antibiotic activity.Results There were linear relationships between the colony extensions and the culture times on common fungi media such as PDA medium, etc.. The amounts of spore produced by the single colony of the fungi were more than 10 7 and gradually increased, but the rates of increase tended to be gentle after 200 h. Antimicrobial tests against 22 microbial strains showed strong inhibition of gram positve bacteria including Bacillus subtilis, Micrococcus tetragenus and Staphylococcus albus, and to gram negative bacteria, including Proteus vulgaris, Salmonella typhi, Aerobacter aerogenes and Salmonella sp., as well as weak inhibition of three mold strains and one actinomycetes strain, but no inhibition was observed in four yeast tested.Conclusion The growth activity and the spore-production ability of Cordyceps hypha are two important factors to infect validly its insect-host. For the growth activity, its strong penetration seems more important than its fast growth. The ability to product numerous spores of Cordyceps hypha may be an important mark of its strong infectivity to insect-host. The antimicrobial tests show that CY-8202 may secrete some metabolites which have a more broad-spectrum antibacterial activity than cordycepin isolated initially from Cordyceps militaris.