Influence of the aeration and pH on the xylose fermentation to ethanol by Pichia stipitis
Roberto, Ines C.; De Mancilha, Ismael M.; Felipe, Maria G.A.; Silva, Silvio S.; Sato, Sunao
Arquivos de Biologia e Tecnologia 37(1): 55-63
The conversion of xylose into ethanol by Pichia stipitis was investigated under different degrees of oxygenation using several combinations of agitation rates and ratios between volume of flasks and volume of the medium (V-F/V-M). The influence of pH upon this bioconversion was also studied. Ethanol yields were found to be dependent on the aeration conditions used. Higher yields were achieved for flasks agitated at 100 and 150 rpm in which the V-F/V-M rations were 5.0 and 2.5, respectively. Under such conditions, it was obtained ethanol yields in the average of 0.36 g/g which corresponds to 70% of the theorical value. No significant difference on the process performance was observed for the various pH tested. However, a slight better yields and productivities were attained when the initial pH was set up to 4.5.