Xylose from Eucalyptus globulus wood as a raw material for bioethanol production

Extracts from auto- and acid-hydrolysis of Eucalyptus globulus wood Chips Were Used as fermentation media to produce ethanol by the yeast Pichia stipitis. pH adjustment with Ca(OH)(2) led to higher yeast activity than with NaOH, probably due to a detoxification effect. Furfural, in the range 0.1 to 0.8 g L-1, did not act as an inhibitor of yeast growth. Substrate inhibition did not occur as well for xylose concentration as high as 60 g L-1. Auto-hydrolysis extracts were submitted to a secondary hydrolysis. The use of different contents of auto- and acid-hydrolysis extracts as natural media, with the yeast previously adapted, showed that 75% (v/v) of acid-hydrolysis extract neutralized with Ca(OH)(2), led to 10 g L-1 ethanol concentration and a yield of 0.36 g(bioethanol) G(sugars)(-1) micro-aerobic conditions, at 30 degrees C and pH 6.0. Although the maximum ethanol concentration reached was still very low, these results compare well to those obtained When Using a synthetic medium with an equivalent concentration of xylose.