Abstract: In order to make better use of Cordyceps militaris, the optimization of medium components and culture conditions was investigated for improved zinc enrichment of C. militaris in liquid-sate fermentation. Meanwhile, the optimal LiCl concentration was chosen to mutate C. militaris. Finally, zinc concentrations in the mycelia of the parental and mutant strains were determined by graphite furnace atomic absorption spectrometry. Results showed that the optimal culture conditions for C. militaris to enrich zinc were as follows: 3% sucrose as the best carbon source, 3% peptone as the best nitrogen source, fermentation time, 6 d; inoculum size, 5%; medium volume, 100 mL/250 mL; and initial ZnSO4 concentration, 100 μg/mL. Under these conditions, the rate of zinc enrichment was 18.54%. The LiCl concentration of 0.15% was optimal for the mutation of C. militaris. Five strains with higher zinc enrichment ability were obtained, giving the highest rate of zinc enrichment of 24.68%, which was increased by nearly 42% as compared with that of the original strain. Therefore the mutants would have promising applications for industrial production.

Key words: Cordyceps militaris, microelement, zinc, enrichment, LiCl mutagenesis