Studies on submerged fermentation of Pleurotus tuber-regium (Fr.) Singer. Part 2: effect of carbon-to-nitrogen ratio of the culture medium on the content and composition of the mycelial dietary fibre

The effects of different carbon/nitrogen (C/N) ratios in liquid media with equal amounts of total organic matter used for submerged fermentation, on the yield of biomass, total dietary fibre (TDF) content and monosaccharide composition of the mycelium of Pleurotus tuber-regium were studied. The mycelial growth was best at a C/N ratio ranging from 18:1 to 36:1 with an optimum value at 24:1. On increasing the C/N ratio of the medium, both the amount of TDF and chitin content in the mycelium of P. tuber-regium decreased while glucan content increased. These results indicate that the proportions of the nitrogen and carbon source in a fermentation medium affect the biosynthesis of cell wall non-starch polysaccharide in mushroom mycelium. The potential use of the mycelium of P. tuber-regium produced by submerged fermentation, as a high fibre food ingredient, is discussed.