초록
<P><B>Highlights</B></P><P>► Wheat straw can be used efficiently for ethanol production using <I>Pichia stipitis</I>. ► Acetic acid, furfural and 5-hydroxymethylfurfural are the main inhibitors found. ► Acetic acid, furfural and 5-hydroxymethylfurfural show a synergic effect. ► Good ethanol yields are obtained with no detoxified steam exploded wheat straw.</P> <P><B>Abstract</B></P><P>The inhibitory effect of the main inhibitors (acetic acid, furfural and 5-hydroxymethylfurfural) formed during steam explosion of wheat straw was studied through ethanol fermentations of model substrates and hydrolysates from wheat straw by <I>Pichia stipitis</I>. Experimental results showed that an increase in acetic acid concentration led to a reduction in ethanol productivity and complete inhibition was observed at 3.5g/L. Furfural produced a delay on sugar consumption rates with increasing concentration and HMF did not exert a significant effect. Fermentations of the whole slurry from steam exploded wheat straw were completely inhibited by a synergistic effect due to the presence of 1.5g/L acetic acid, 0.15g/L furfural and 0.05g/L HMF together with solid fraction. When using only the solid fraction from steam explosion, hydrolysates presented 0.5g/L of acetic acid, whose fermentations have submitted promising results, providing an ethanol yield of 0.45g ethanol/g sugars and the final ethanol concentration reached was 12.2g/L (10.9g ethanol/100g DM).</P>