Effect of nitrogen sources on the growth and carotenoid production in Cordyceps militaris

Abstract:

[Background] Cordyceps militaris is one of the famous medicinal fungi. Carotenoid is not only an important active component but also affects the appearance of fruiting body. However, the factors regulating its production are unknown. [Objective] To reveal the effects of nitrogen sources on the growth and carotenoid production of C. militaris. [Methods] The growth rate, conidia and carotenoid production on media with different nitrogen sources were determined and the optimum nitrogen sources were selected. The effects of nitrogen concentration on carotenoid production of C. militaris fruiting body under different light conditions were further determined. [Results] There were significant differences in growth and carotenoid production of C. militaris on media with different nitrogen sources. The growth rate was the fastest in wheat bran and soybean powder media, showing as fluorescent yellow and very weak red, respectively. The conidia produced in peptone and yeast extract media were significantly more than that in other nitrogen sources (P<0.01), and the colony was orange. There was no pigment production in inorganic nitrogen source media except for trace pigments on the back of plate of glutamic acid and ammonium chloride. It was found that the carotenoid content increased with the increase of peptone concentration in the range of 0?3%. Blue light was more suitable for the carotenoid production in fruiting body than white light. The carotenoid contents were the highest with the peptone concentration of 1% under both white and blue light conditions, 2 809.38±386.24 μg/g and 4 093.75±518.37 μg/g respectively. [Conclusion] Nitrogen source and its concentration significantly affected the carotenoid production in C. militaris. Blue light and peptone concentration of 1% were the best conditions for carotenoid production in fruiting bodies. This study will be helpful for cultivating C. militaris fruiting body rich in carotenoid.