FLOCCULENT YEAST POPULATION DYNAMICS IN A CONTINUOUS TOWER REACTOR FOR ETHANOL FUEL PRODUCTION

摘要

The purpose of this work was to follow the population dynamics of 6 yeast strains in a tower reactor for continuous ethanol production. The strains studied have grown flocculently and shown a fermentation performance appropriate to industrial use. Thetwo glass reactors used were connected in line and fed with a sucrose based synthetic medium. For 15 days, the yeast populations were quantified through colony count over a differential medium (WLN). In such medium, the 6 strains tested were differentiated for presenting colonies of morphological patterns distinct from one another. The results have shown that there was a selection pressure within the reactors, since only two (Y5 and Y6) of the six inoculated strains were found in the process at the endof the trial. It is clear that when this type of unit is projected for industrial use, in addition to using a flocculent strain with suitable fermentation performance, it is equally necessary that a careful study of the raw material be used and the conditions in which one intends to act.