초록
<P><B>ABSTRACT</B><P> To improve the enzymatic hydrolysis (saccharification) of lignocellulosic biomass by <I>Trichoderma reesei</I> , a set of genes encoding putative polysaccharide-degrading enzymes were selected from the coprophilic fungus <I>Podospora anserina</I> using comparative genomics. Five hemicellulase-encoding genes were successfully cloned and expressed as secreted functional proteins in the yeast <I>Pichia pastoris</I> . These novel fungal CAZymes belonging to different glycoside hydrolase families ( <I>Pa</I> Man5A and <I>Pa</I> Man26A mannanases, <I>Pa</I> Xyn11A xylanase, and <I>Pa</I> Abf51A and <I>Pa</I> Abf62A arabinofuranosidases) were able to break down their predicted cognate substrates. Although <I>Pa</I> Man5A and <I>Pa</I> Man26A displayed similar specificities toward a range of mannan substrates, they differed in their end products, suggesting differences in substrate binding. The N-terminal CBM35 module of <I>Pa</I> Man26A displayed dual binding specificity toward xylan and mannan. <I>Pa</I> Xyn11A harboring a C-terminal CBM1 module efficiently degraded wheat arabinoxylan, releasing mainly xylobiose as end product. <I>Pa</I> Abf51A and <I>Pa</I> Abf62A arabinose-debranching enzymes exhibited differences in activity toward arabinose-containing substrates. Further investigation of the contribution made by each <I>P. anserina</I> auxiliary enzyme to the saccharification of wheat straw and spruce demonstrated that the endo-acting hemicellulases ( <I>Pa</I> Xyn11A, <I>Pa</I> Man5A, and <I>Pa</I> Man26A) individually supplemented the secretome of the industrial <I>T. reesei</I> CL847 strain. The most striking effect was obtained with <I>Pa</I> Man5A that improved the release of total sugars by 28% and of glucose by 18%, using spruce as lignocellulosic substrate. </P></P>