Optimizing vitamin B12 biosynthesis by mycelial cultures of Lentinula edodes (Berk.) Pegl.

Preparations derived from Lentinula edodes (Berk.) Pegl. are widely used as dietary supplements, they contain compounds with immune system enhancing and chemopreventive properties. These preparations contain a blend of minerals and vitamins, including vitamins A, D, B1, B2, C, and niacin, but only scant vitamin B12. Our goal was to optimize the growth conditions of submerged mycelial cultures of L. edodes in order to obtain a new dietary supplement enriched in vitamin B12. We designed a biotechnological process in which cobalamin precursors, cobalt chloride and the methyl donors betaine, methionine, and choline, were added to the culture medium. The vitamin B12 content in mycelial extracts was determined by RP-HPLC, while total Co2+ content was determined by HPIC. At the optimal Co2+ concentration (40 μg/mL), the vitamin B12 level in L. edodes mycelium reached 95 μg/g of dry weight. All methyl donors had a positive effect on cobalamin biosynthesis, at least doubling its concentration in mycelia as compared mycelia grown in non-enriched medium. The amount of cobalamin in submerged cultivated mycelia of L. edodes was 10,000-fold higher than that recorded for fruiting bodies. Our results suggest that these optimized culture conditions could be applied to obtain a new cobalamin-enriched dietary supplement derived from L. edodes.