[Biosynthesis of vitamins B by the fungus Pleurotus ostreatus in a submerged culture].

The intra- and extracellular contents of vitamins were studied in the course of submerged cultivation of the higher basidial mushroom Pleurotus ostreatus (Jacq.: Fr.) Kummer st. IMBF-1300 on liquid nutrient media. This strain was found to be autotrophic in respect of thiamin (vitamin B1), riboflavin (vitamin B2), niacin (vitamin B5), pyridoxine (vitamin B6) and biotin (vitamin B7), but it failed to synthesize cyanocobalamin (vitamin B12). The composition and pH of the culture medium, containing such complex biostimulating supplements as maize extract and concentrated potato sap noticeably influence the contents of vitamins B1, B5 and B7 in the mycelium, and to a less degree they change the level of the intracellular biosynthesis of vitamins B2 and B6. Higher excretion of vitamins B5, B7 and especially B6 was observed on the semisynthetic media during the postexponential growth. Under experimental conditions vitamins B1 and B2 were accumulated only in the cells. The dry mycelium of P. ostreatus obtained by submerged cultivation on liquid media is a valuable source of B vitamins and, especially, of niacin. Thus the oyster mushroom and other edible mushrooms can be put at one of the top places among food-stuffs by the content of niacin.