S.cerevisiae is the most commonly used microorganism for
bioethanol production because of its high production rate, but it
cannot use xylose for fermentation which is one of the main sugars
present in lignocellulosic biomass, especially in fruit pomaces.
Various filamentous fungi, such as certain Trichoderma and Aspergillus
species, have been reported to produce bioethanol as the
main fermentation product from lignocellulosic biomass, directly
[8,9]. These fungi are thought to contain two biological systems:
one system produces cellulase enzyme for degradation of cellulose
to fermentable sugars under aerobic conditions; the second system
produces ethanol under anaerobic conditions [10]. However,
although Trichoderma and Aspergillus are able to utilize five of the
lignocellulosic sugars (glucose, mannose, galactose, xylose and
arabinose) and the ability of direct fermentation of lignocellulose to
bioethanol, they do not produce bioethanol with high yield and
high rate. Therefore, in order to increase the fermentation yield,
utilization of cocultures could be a convenient way of producing
bioethanol from agricultural residues.