Abstract: A 27－3IV fractional factorial design (FFD) was employed to determine culture medium ingredients affecting extracellular polysaccharide (EPS) production by P. baumii Pilát, such as glucose, peptone, yeast extract, ammonium oxalate, KH2PO4, MgSO4 and thiamine (VB1). Glucose, yeast extract and ammonium oxalate were identified as key affecting factors, and their optimal levels were further investigated by means of a central composite design. The average EPS yield from 5 parallel fermentation experiments carried out using a culture medium (g/L) composed of glucose 34.12, yeast extract 5.01, peptone 4, MgSO4 0.75, KH2PO4 1, VB1 0.0075 and ammonium oxalate 0.88 was (2.363 ± 0.04)g/L, which was in substantial agreement with the predicted value (2.342 g/L). It can be seen clearly that the developed regression model is applicable for the optimization of culture medium for EPS production.

Key words: Phellinus baumii Pil á t, extracellular polysaccharide, fractional factorial design, central composite design