Pleurotus species are recognized for producing beta-glucans with important medicinal properties as a constituent of the cellular wall of the fruiting body or of the mycelium. The aims of this work were to select a culture medium that maximized the production of biomass and polysaccharides produced by Pleurotus ostreatus DSM 1833 and to evaluate the selected medium in two values of initial oxygen transfer rate -K(L)a (10.2 and 19.3 h(-1)). A 2**4 factorial design was constructed to evaluate the supplementation of wheat extract with corn steep liquor -CSL (10 or 20 g L-1), yeast extract -YE (2 or 5 g L-1), ammonium sulfate - AS (0 or 5 g L-1) and glucose (20 or 40 g L-1), In terms of maximum productivity in biomass and global productivity in polysaccharides, the best values were obtained when 5 g L-1 of YE and 40 g L-1 of glucose were used. In terms of maximum concentration of biomass, the best results were obtained when 20 g L-1 of CSL and 40 g L-1 of glucose were used. The best results in terms of production of biomass and polysaccharides were achieved when lower initial K(L)a (10.2 h(-1)) was used. (C) 2007 Elsevier Ltd. All rights reserved.