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.
© 2006 Elsevier B.V. All rights reserved.
The optimization of submerged culture conditions for mycelial growth and exopolysaccharide (EPS) production in an ediblemushroom Tremella fuciformis was studied in shake flasks and bioreactors. The temperature of 28 ◦C and pH 8 in the beginningof fermentation in agitated flasks was the most efficient condition to obtain maximum mycelial biomass and EPS. The optimalmedium constituents were as follows (g L−1): glucose 20, tryptone 2, KH2PO4 0.46, K2HPO4 1 and MgSO4·7H2O 0.5. The funguswas cultivated under various agitation and aeration conditions in a 5 L stirred-tank bioreactor. The maximum cell mass andEPS production were obtained at a relatively high agitation speed of 200 rpm and at an aeration rate of 2 vvm. The flow behaviorof 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 studyrevealed that the fungus grows in mainly three different yeast-like forms: ovoid, elongated, and double yeast forms. The high populationof the elongated yeast has a very close relationship to high EPS production. The EPS were protein-bound polysaccharidesconsisted of mainly mannose, xylose, and fucose. The molecular weights of EPS were determined to be (1.3–1.5)×106.© 2006 Elsevier B.V. All rights reserved.
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