On the Biotechnological Production of Erinacine C based on Biogenic Byproducts

The demand for medicinal mushrooms as dietary supplement is steadily increasing as mushrooms exhibit various positive effects on the human health. Especially secondary metabolites can be detected in the fruiting bodies and account for those effects. Erinacine C is such a secondary metabolite that is synthesized by the edible mushroom Hericium erinaceus. This medicinal mushroom is as functional food available in the dosage forms of powder and extracts of fruiting bodies. Nevertheless, the products contain low amounts of erinacine C only. The production of erinacine C in large amounts has not been achieved by submerged cultivation, yet. Based on the potential as therapeutic to treat Alzheimer's disease, it is of interest to develop a bioprocess providing increased amounts of this compound. The aim of this study is to investigate the production of erinacine C resulting in two different dosage forms. On the one hand a bioprocess is developed to generate the food grade product edible biomass with an increased erinacine C content. On the other hand the fermentation product is further treated to generate purified erinacine C as product for functional food and pharmaceutical applications. Besides synthetic precultivation media, the utilization of biogenic byproducts was investigated resulting in a precultivation using acidic treated wheat bran or acidic treated brewer's spent grain as medium component only. The subsequent main fermentation using biomass precultivated on biogenic byproducts yielded significantly decreased erinacine C contents in the biomass. Hence, the production of erinacine C using biomass grown on synthetic precultivation media is more meaningful. Highest erinacine C concentrations of 2.7 g/L, which corresponds to a content of 300 mg erinacine C per g cell dry weight, were achieved using an inoculation ratio of 5:10 (v/v) and medium buffered to the pH value of 7.5. The biomass, containing erinacine C, was extracted with ethyl acetate and the extracts further purified by centrifugal partition chromatography (CPC). Hereby, 100 mg of erinacine C with a purity above 99 % were isolated in one CPC trial. The corresponding production costs for both dosage forms were estimated to 16,000 € per kg purified erinacine C and to 4,000 € per kg erinacine C regarding the product food grade biomass with an erinacine C content of 16 wt.-%. The corresponding production costs for biomass containing erinacine C are 600 € per kg dry matter.