Selection of High-avermectin Strain by Protoplast Mutation

Avermectin,which has the antiparasitic activity, is a secondary metabolite produced by srteptomyces avermitilis. The improvement of the strain is the key factor to raise theaverrmectin production. By inducing the avermectin protoplast and L-Ile being as a select model, the high production strain fistly was selected, the avermectin protoplast was prepared. The protoplasts were induced by UV radiation at the condition of stiring, lastly they were cultured on the plate containing 0.5% L-Ile. A new strain was obtained which potency of B1a has raised 35.4% than the beginning strain.