Formation of cordycepin in the fungus Cordyceps militaris grown on side-stream of black soldier fly (Hermetia illucens) rearing

Abstract This study investigated the formation of cordycepin in two Cordyceps militaris strains (DSM23612, DSM1153) and Cordyceps ophioglossoides DSM1206 grown on side-stream of black soldier fly (BSF, Hermetia illucens ) rearing, namely puparia and deceased flies. Preliminary submerged experiments showed that only C. militaris DSM23612 demonstrated notable cordycepin production with deceased BSF being the preferred substrate. After 21 days of cultivation, the highest amount of cordycepin with 283 mg/L (2.4 mg/g BSF ) was obtained in cultures with 120 g/L BSF. Addition of glucose and palm oil decreased cordycepin contents, while peptone and ammonium sulfate increased them. In cultures with 120 g/L BSF, the addition of peptone significantly increased the amount of cordycepin by 1.4-fold to 402 mg/L (3.4 mg/g BSF ), which was the highest amount of cordycepin in submerged cultures. In comparison to media with malt extract, potato dextrose broth or glucose, emersed cultures of C. militaris DSM23612 on BSF with water yielded the highest cordycepin content with 1,963 mg/kg (5.2 mg/g BSF ) after 42 days. Different ratios of rice and BSF showed that cordycepin production was mainly related to BSF content, with yields after 28 days being 21 times higher with BSF than when grown on rice alone. The addition of peptone to emersed cultures significantly increased cordycepin production, with the highest cordycepin concentration of 2,943 mg/kg (7.3 mg/g BSF ) being achieved with 100 g/L peptone after 28 days. The results show that BSF side stream is a promising substrate for cordycepin production with C. militaris .