5. Saccharification Process of Napier Grass
SA of non-treated and LMAA-pretreated Napier grass
(10.0 g) were performed using a cellulase from Acremonium
cellulolyticus (Acremozyme KM, Kyowa Kasei, 1.0 g) at
45°C in an acetate buffer (60 mL, pH 5.0). SA of nontreated
Napier grass produced the total saccharides in 54%
yield. In the case of Napier grass which was subjected the
LMAA-pretreatments for four weeks, the yield of saccharides
was 67% which was the higher than those of one and two
weeks. Fig. 3 shows the time-conversion of the SA yields
of the LMAA-pretreated Napier grass. Although the glucose
increased rapidly to reach the maximum amounts until 48 h,
xylose increased gradually even at SA for 360 h. Thus the
SA of xylan was very slow.
In order to shorten the SA time, a xylanase from
Trichoderma longibrachiatum (reesei) (Sumizyme X, Shin
Nihon Chemicals) was used in addition to cellulase. In the
SA of LMAA-pretreated Napier grass, dependence of the
saccharide yields on the fraction (FX) of xylanase in mixed
enzyme was examined: FX = weight of xylanase/(weight of
cellulase + weight of xylanase). Optimal FX value was
determined to be 0.50. In SA of the LMAA-pretreated