ABSTRAKT

The influences of submerged cultivation conditions on both mycelial biomass and exopolysaccharide (EPS) produced by the medicinal mushroom Oudemansiella radicata in shaken flasks and 5-L bioreactors were studied. In shaken flasks, the suitable conditions of the medium volume, rotation rate, and carbon source were 50 mL, 100 rpm, and lactose to obtain maximum mycelial biomass and EPS, respectively. The inoculum ratio and nitrogen source were 10% (v/v) and tryptone for the mycelial biomass yield and 5% (v/v) and peptone for the EPS production. Then, the central composite rotation design and response surface analysis were used to optimize the suitable medium compositions for the production of mycelial biomass and EPS. The model estimated that the maximal production of mycelial biomass (3.36 g/L) and EPS (1420 mg/L) could be obtained when Ou. radicata was cultivated under 5.00% (w/v) lactose, 7.02% peptone, and initial pH 5.20. In a 5-L stirred tank bioreactor, the maximum mycelial growth and EPS production by Ou. radicata with 10% of inoculum were 12.29 g/L and 3078 mg/L, respectively, under an aeration rate of 1 vvm and an agitation speed of 125 rpm after 11-day cultivation. The production of mycelial biomass and EPS in a 5-L stirred tank bioreactor was 3.66- and 2.17-fold, respectively, for predicted yields of mycelial biomass and EPS in a regression model and 1.78- and 8.02-fold for those in basal medium by shaken flasks.