Nitrogen Sources and the Growth Response of Pleurotus ostreatus Mushroom Mycelium

Abstract The effect of different sources of nitrogen on the mycelial growth of the edible mushroom Pleurotus ostreatus has been studied. The organic nitrogen sources tested were yeast extract, peptone, and urea, and the inorganic nitrogen sources were ammonia solution, ammonium phosphate dibasic, ammonium citrate, ammonium nitrate and potassium nitrate. The concentrations of the different sources of nitrogen were calculated to provide 0.5 g/L of nitrogen to both a synthetic and a peat extract medium. The ammonia solution was used to provide nitrogen and also to adjust the pH of the peat extract medium. Different concentrations of yeast extract (1.0, 3.0, 5.0, 7.5 and 10.0 g/L), and (NH4)2HPO4 (0, 2.5, 5.0 and 7.5 g/L) (which were the best nitrogen sources added to the peat extract medium) were studied for their effects on growth and on crude protein production. Ammonium citrate was the best nitrogen source added to the synthetic medium, producing 14.7 g/L of dry mycelium, which was the highest biomass concentration obtained in this work. The effect of the carbon: nitrogen ratios in the culture media on the mycelial growth is presented.