Erinacine C: A novel approach to produce the secondary metabolite by submerged cultivation of Hericium erinaceus.

Erinacine C is a cyathane scaffold-based secondary metabolite, which is naturally produced by the filamentous fungus Hericium erinaceus and has a high potential to treat nervous diseases such as Alzheimer's disease. The investigated approach consists of combining an optimised precultivation of H. erinaceus with an enhanced erinacine C production by developing a suitable main cultivation medium enabling the utilisation of high biomass contents. The final erinacine C production medium is buffered by 100 mM HEPES to ensure a stable pH value of 7.5 during main cultivation at inoculation ratios of up to 5:10 (v/v). The medium components, such as 5.0 g L(-1) oatmeal, 1.5 g L(-1) calcium carbonate, and 0.5 g L(-1) Edamin(®) K are crucial for an increased erinacine C production. Besides, different carbon to nitrogen ratios of 25, 64, and 103 do not affect the erinacine C synthesis. The investigated approach enables the production of 2.73 g erinacine C per litre main cultivation broth, which is tenfold higher than published data. In addition, erinacine C biosynthesis is determined to occur mainly in the first six days of main cultivation.