Mitchell et al (2010) [15] produced crude
unprocessed cellulase extracts by solid-state
fermentation of Trichoderma reesei on ground
wheat straw. While cellulase yields were not high
they were sufficient to produce ethanol from
wheat straw in simultaneous saccharification and
fermentation with Saccharomyces cerevisiae. As
little as an additional 5% of the material converted
to ethanol may be employed for cellulase
production suggesting an inordinate quantity of
additional substrate would not be required. These
findings suggest a simplified crude cellulase
process at the site of ethanol production using a
common lignocellulosic substrate which employed
in lieu of commercial enzyme preparations. A
series of solid-state fermentations were carried
out starting with 25 or 50 g dry ground wheat
straw and 50 or 100 ml nutrient solution in 500 ml
Schott bottles with cotton bungs and aluminum foil. Initially batch solid-state fermentations,
inoculated with a common spore suspension, were
run in duplicate for 10 and 14 days. Diluted crude
cellulase extract obtained from solid-state
fermentations was used to carry out the
simultaneous saccharification and fermentation of
ground wheat straw to ethanol. It was desired to
see if the crude unprocessed cellulase could
actually be used to produce ethanol, to get an
indication of the levels of cellulase activity
required and to see the effect of varying cellulase
activity on the amount of ethanol produced. Two
batch fermentations and one fed-batch
fermentation were carried out.