Optimization of the liquid culture medium composition for high carotenoid production by Cordyceps militaris and the investigation on the improvement of carotenoid extraction

The cereal-based medium for liquid fermentation was optimized according to the carotenoids production of three strains of Cordyceps militaris CM-03, CM-04 and CM-11.The media components of this work contained several kinds of grains such as wheat ( W) , corn ( C) , bean ( B) , rice ( R) , bran ( Br) and inorganic salts like MgSO₄·7H₂O ( Mg) , KH₂PO₄ ( KHP) and vitamin B₁ ( VB₁) .The results showed that the best culture medium formula for the carotenoids accumulation by Cordyceps militaris CM-03 consisted of W ( 1.4 g·L^-1) , C ( 2.8 g·L^-1) , B ( 0.3 g·L^-1) , Mg ( 0.1 g·L^-1) , KHP ( 0.1 g·L^-1) and VB₁ ( 0.05 mg·L^-1) , with natural pH, with the carotenoids yield of ( 694.8 ± 15.4) μg/g.For Cordyceps militaris CM-04, its highest carotenoids output was ( 708.5 ± 25.8) μg/g under the formula consisted of R ( 1.2 g·L^-1) , C ( 0.6 g·L^-1) , B ( 0.3 g·L^-1) , Mg ( 0.1 g·L^-1) , KHP ( 0.1 g·L^-1) , VB₁ ( 0.05 mg·L^-1) with natural p H.The highest carotenoids output of Cordyceps militaris CM-11 was ( 700.5 ± 19.1) μg/g with natural p H, the formula formed by W ( 1.7 g·L^-1) , C ( 2.6 g·L^-1) , B ( 0.3 g·L^-1) , Mg ( 0.1 g·L^-1) , KHP ( 0.1 g·L^-1) and VB1 ( 0.05 mg·L^-1) .The extraction process with ethanol was also optimized in this work, and the results showed that the optimal extraction condition was as follows: grinding with quartz sand, ethanol concentration 60%, material to liquid ratio 1∶ 40, water bath temperature 80 ℃, extraction level 2, and extraction rate of92.8%.