The optimization of submerged culture conditions for mycelial growth and exopolysaccharide (EPS) production in an edible
mushroom Tremella fuciformis was studied in shake flasks and bioreactors. The temperature of 28 ◦C and pH 8 in the beginning
of fermentation in agitated flasks was the most efficient condition to obtain maximum mycelial biomass and EPS. The optimal
medium constituents were as follows (g L−1): glucose 20, tryptone 2, KH2PO4 0.46, K2HPO4 1 and MgSO4·7H2O 0.5. The fungus
was cultivated under various agitation and aeration conditions in a 5 L stirred-tank bioreactor. The maximum cell mass and
EPS production were obtained at a relatively high agitation speed of 200 rpm and at an aeration rate of 2 vvm. The flow behavior
of the fermentation broth was Newtonian and the maximum apparent viscosity (35 cP) was observed at a highly aerated condition
(2 vvm). The EPS productivity in an airlift reactor was higher than that in the stirred-tank reactor. The morphological study
revealed that the fungus grows in mainly three different yeast-like forms: ovoid, elongated, and double yeast forms. The high population
of the elongated yeast has a very close relationship to high EPS production. The EPS were protein-bound polysaccharides
consisted of mainly mannose, xylose, and fucose. The molecular weights of EPS were determined to be (1.3–1.5)×106.
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