Abstract:

In the present study, investigations were carried out to optimize the medium components for enhanced
enrichment of the dietary microelement selenium (Se) in Cordyceps militaris mycelia. The Cordyceps militaris strain
No.13 preserved in our laboratory was improved by low-energy nitrogen ion beam implantation under optimal operating
conditions to increase Se enrichment in the mycelia. The Se contents in the original and mutant strains were determined
by graphite furnace atomic absorption spectrometry (GFAAS). Results showed that the optimal medium components
for Se enrichment in Cordyceps militaris mycelia were determined as follows: peptone 3 g/100 mL, glucose 3 g/100 mL
and Na2SeO3 8 μg/mL at pH 7.0, resulting in a selenium enrichment rate of 21.58%. The optimal parameters for lowenergy
nitrogen ion beam implantation were achieved at an energy of 10 keV and a dose of 1.82×1015 ions/cm2. Ten
mutant strains showing higher Se-enriching capacity were obtained. The highest Se enrichment rate of 30.97% was
observed, nearly 42% higher than that of the original strain.

Key words: Cordyceps militaris, selenium, low-energy ion beam, enrichment, implantation