Biomass and exopolysaccharide production in submerged cultures of Pleurotus ostreatoroseus Sing. and Pleurotus ostreatus "florida" (Jack.: Fr.) Kummer.

The species of the genus Pleurotus produce large amounts of biomass and exopolysaccharide (EPS) in submerged cultures, which may be used for biotechnological purposes. In the present work two Brazilian autochthonous strains of edible Pleurotus (P. ostratoroseus Sing. and P. ostreatus "florida") were used. The fungi grown in liquid Potato Dextrose medium (PD) were used as inocula to cultivate those microorganisms in the POL culture medium. After a 9-day incubation, the optimal growth time for biomass production, P. ostreatus "florida" presented higher biomass production (22.8 g d.w./l) than P. ostreatoroseus (16.8 g d.w./l). After a 7-day incubation, the optimal growth time for EPS production, P. ostreatoroseus produced higher amounts of crude EPS (5.8 g d.w./l) than P. ostreatus "florida" (1.4 g d.w./l). Relative carbohydrate composition for P. ostreatoroseus and P. ostreatus "florida" EPS were: glucose (95.5-87.7), galactose (traces - 4.9), mannose (traces - 3.1), xylose (1.3-2.5), and arabinose (3.2-1.8). Lower ammonium sulfate concentration in the POL culture medium increased the exopolysaccharides production by P. ostreatoroseus.