Enhanced saccharification of reed and rice straws by the addition of β-1,3-1,4-glucanase with broad substrate specificity and calcium ion

Abstract

The possibility of using additive enzymes to improve the saccharification of lignocellulosic substrates with commercial cellulolytic enzymes was studied. Reed (Phragmites communis) and rice (Oryza sativa) straw powders were pretreated with NaOH/steam via a high-temperature explosion system. The saccharification of untreated reed and rice straw powders by commercial enzymes (Celluclast 1.5 L + Novozym 188) was not significantly increased by the addition of xylanases (Xyn10J, XynX), a cellulase (Cel6H), and a β-1,3-1,4-glucanase (BGlc8H) with broad substrate specificity. The saccharification of the pretreated reed and rice straw powders by the commercial enzymes was increased by 10.4 and 4.8 %, respectively, by the addition of BGlc8H. In the presence of Ca2+ and BGlc8H, the saccharification of the pretreated reed and rice straw powders by the commercial enzymes was increased by 18.5 and 11.7 %, respectively. No such effect of Ca2+ was observed with Xyn10J, XynX, or Cel6H. The results suggest that the enzymatic conversion of lignocellulosic biomass to reducing sugars could be enhanced by certain additive enzymes such as β-1,3-1,4-glucanase, and that the enhancement could further be increased by Ca2+.