Estudo da imobilização de células de Saccharomyces cerevisiae em gel de alginato de cálcio no processo de fermentação alcoólica

Abstract

This work aims to offer a contribution for the development of an economic technology for ethanol production by the biotechnological approach. In this direction, it investigates the conditions for Saccharomyces cerevisiae cells immobilization in calcium alginate and addresses the operational stability aspects of a stirred batch bioreactor in order to deal with important factors in the immobilized cell bioreactor operation. A Response Surface Methodology (RSM), using a statistical screening design and a central composite design, allied with a desirability function analysis, were used to evaluate the fermentation efficiency of the pellets and to optimize the cells immobilization conditions. A 2 liters stirred batch bioreactor with temperature control was used to monitor the free and immobilized cell concentrations, ethanol and glucose concentrations were sampled at each 2 hours during the duration of the fermentation process. The results in the explored experimental range indicate that the proposed methodology leads up to a sufficiently robust immobilization procedure. The pellets treated with Al(NO3)3 presented a great deal of stability and metabolic activity for ethanol production, reaching conversion of up to 94% of the Pasteur yield.