Utilization of Corncob Biochar in Cultivation Media for Cordycepin Production and Biomass of <i>Cordyceps militaris</i>

Cordyceps militaris is an entomopathogenic fungus. It is well-known as a rich source of bioactive compounds called cordycepins and adenosines, which are useful in medicinal applications. The effects of medium components on cordycepin and adenosine production by C. militaris, obtained by adding different conditions of corncob biochar in solid media, were investigated in this study. The medium components, which mixed 0.1, 0.3, 0.5, 1, 5 and 10 g of biochar with rice berries, were optimized to improve the yield of biomasses, cordycepins, and adenosines. The results showed that 10 g of biochar mixed with a rice berry medium was the optimal medium condition for the highest dry fruiting body weight (DFW) and cordycepin yield (CY) at 3.6 kg/bottle and 20.5 mg/g, respectively, but the adenosine yield (AY) was similar to that in other conditions. Moreover, the SEM showed that the mycelia of C. militaris attached to the biochar surface (pores) and used it as the resident. EDS analysis from the basal medium indicated that C and O were present in the mycelia of C. militaris with the average values of 25.6% and 71.4%, respectively. This study provides an effective cultivation method by using agricultural residue, and biochar corncob as a high concentration of carbon for increasing the biomass, cordycepin, and adenosine yield of C. militaris. The information obtained in this study is fundamental and useful to the development of a C. militaris cultivation process for the efficient production of cordycepin on a large scale. The findings suggest that the system design of the cultivation medium is crucial for growth and cordycepin production