Study of biocatalyst to produce ethanol from starch - Coimmobilization of glucoamylase and yeast in gel

This article presents a detailed study on the conditions for achieving a st able biocatalyst to be used in the production of ethanol from starch. Diffe rent pellets were used depending on which characteristic of the biocatalyst was being studied: (a) Saccharomyces cerevisiae entrapped in pectin or cal cium alginate gel particles; (b) silica containing immobilized glucoamylase entrapped in pectin gel particles; or (c) pectin gel particles, with the s ilica-enzyme derivative and yeast coimmobilized. The influence of several v ariables on the mechanical resistance of the particle, on the viability of the microorganism, and on the rate of substrate hydrolysis was studied with biocatalyst. The best conditions found were 6% pectin gel, 2-mm particle d iameter, and cure in 0.2 M CaCl2.2H(2)O/60 mM acetate buffer, pH 4.2, for g el preparation; and 6.0 g/L of CaCl2.2H(2)O in the fermentation medium. Bio catalyst (c) was successfully tasted for the production of ethanol from liq uefied manioc flour syrup.