Fuel ethanol industry presents different problems during bioreactors operation. One of them is the
unexpected variation in the output ethanol concentration from the bioreactor or a drastic fall in the
productivity. In this paper, a compilation of concepts and relevant results of several experimental and
theoretical studies about dynamic behavior of fermentation systems for bioethanol production with Saccharomyces
cerevisiae and Zymomonas mobilis is done with the purpose of understanding the stability
phenomena that could affect the productivity of industries producing fuel ethanol. It is shown that the
design of high scale biochemical processes for fuel ethanol production must be done based on stability
studies.