The environment concern over the us

The environment concern over the use and depletion of
fossil fuels, the search for alternative fuel is desirable
(Liang et al., 2008). Ethanol has attracted worldwide
attention due to its potential use as a transportation fuel
(Kumar et al., 2009a). Ethanol is traditionally produced in
the batch fermentations by yeasts, mostly
Saccharomyces cerevisiae and their interspecies hybrids,
which provide the low productivity (Gunasekaran and Raj,
1999; Rebroš et al., 2005). High ethanol productivity from
cheaper and renewable sources and minimum energy