1. Introduction
Simultaneous saccharification and fermentation (SSF) processes firstly described by Takagi et al. [1], combine enzymic hydrolysis of cellulose with simultaneous fermen- tation of the sugars obtained to ethanol. In the SSF process, the stages are virtually the same as in separate hydrolysis and fermentation systems, except that both are performed in the same reactor. Thus, the presence of yeast together with the cellulolytic enzyme complex reduces the accu- mulation of sugars within the reactor—thereby increasing yield and saccharification rate with respect to separate sac- charification and fermentation [2]. Another advantage of this approach is that a single fermenter is used for the entire process—thereby curbing the investment costs. In addi- tion, the presence of ethanol in the culture medium causes the mixture to be less vulnerable to invasion by undesired microorganisms [3].