The production cost of cellulolytic enzymes is a major contributor to the high cost
of ethanol production from lignocellulosics using enzymatic hydrolysis. The aim of
the present study was to investigate the cellulolytic enzyme production of Trichoderma
reesei Rut C 30, which is known as a good cellulase secreting micro-organism, using
willow as the carbon source. The willow, which is a fast-growing energy crop in Sweden,
was impregnated with 1-4% SO2 and steam-pretreated for 5 min at 206 degrees C. The
pretreated willow was washed and the wash water, which contains several soluble sugars
from the hemicellulose, was supplemented with fibrous pretreated willow and used for
enzyme production. In addition to sugars, the liquid contains degradation products
such as acetic acid, furfural, and 5-hydroxy-methylfurfural, which are inhibitory
for microorganisms. The results showed that 50% of the cellulose can be replaced with
sugars from the wash water. The
highest enzyme activity, 1.79 FPU/mL and yield, 133 FPU/g carbohydrate, was obtained
at pH 6.0 using 20 g/L carbon source concentration. At lower pHs, a total lack of
growth and enzyme production was observed, which probably could be explained by furfural
inhibition.
