Effect of mineral elements on colony types of Cordyceps militaris in subculturing.

The effect of mineral elements on colony types of Cordyceps mi1itaris in subculturing was reaseached in order to explore a most suitable mineral elements formulation for maintainning the stablility of the excellent colony type.A good strain, named L20,was subcultured on different media with different mineral elements for twelve times by orthogonal experimental method.The results showed that there were seven colony types of L20 after subcultured,among which typeⅠ,Ⅱ,ⅢandⅤ could form fruit-body,Ⅳ,ⅥandⅦ,however,could not.TypeⅠhad the highest yield of fruit-body,Ⅲin the middle,Ⅱthe lowest;Ⅴhad all abnormal fruit-body.Distribution patterns of colony types in different media were as follow:typeⅠandⅢ mainly in 1~10 generations;typeⅡin 1~4 generations;typeⅤ,Ⅳ,ⅥandⅦmainly after 4 generation.TypeⅠwas the best kind of colony type and the medium contained K+(1.0g·L-1),Mg2+(0g·L-1),Ca2+(0.02g·L-1),Mn2+(0μg·L-1),Zn2+(250μg·L-1 or 375μg·L-1)and could maintain typeⅠmore stable.The main morphological features of typeⅠwere saffron yellow colony color; aerial of hyphae at middle level,dense floss colony texture with concentric circle;and sector in subculturing.The degradation of typeⅠcolony could be delayed by K+(1.0 g·L-1),Ca2+(0.02g·L-1),Zn2+(250μg·L-1or 375μg·L-1)and accelerated by Mn2+,Mg2+.