Abstract:

An orthogonal array design involving 9 tests of four crucial factors including medium type, fill volume of medium in a 250 ml flask, culture time and selenium concentration at three levels for maximizing selenium enrichment in mycelia of Cordyceps militaris. The selenium content in mycelia of Cordyceps militaris was determined by ICP-MS method. The effects of the four factors on biomass of mycelia declined in the following order: culture time ＞ selenium concentration ＞ medium type ＞ fill volume of medium in a 250 ml flask, and those on selenium enrichment ratio in the following order: selenium concentration ＞ medium type ＞ culture time ＞ fill volume of medium in a 250 ml flask. The maximum selenium enrichment was achieved by the culture for 6 d with a defined medium containing 10 μg/ml selenium at 3/5 fill proportion in a 250 ml flask and the contents of two major medicinal components, cordycepic polysaccharide and cordycepin, in cultured mycelia of C. militaris reached 226.3 and 2.22 mg/g, which were 3.4 and 5.8 times of those in normal mycelia, indicating selenium enrichment was beneficial to the sharp increase of medicinal value C. militaris.

Key words: Cordyceps militaris, selenium, cordycepic polysaccharide, cordycepin