The permeabilization was used to transform microorganisms in cell biocatalysts with high enzymatic activity. The Saccharomyces fragilis IZ 275 yeast cells were permeabilized with ethanol, as permeabilizing agent. To optimize the permeabilization conditions were used the design of Box-Behnken 15 trials (3 central points). The independent variables and their levels were ethanol (29, 32 and 35%), temperature (15, 20 and 25°C) and time (15, 20 and 25 min). The answer (Y) function has betagalactosidase activity (U mg-1). The optimum conditions for obtaining a high enzymatic activity were observed in 35% ethanol concentration, temperature 15ºC and 20 min. treatment time. The maximum activity of the enzyme beta-galactosidase obtained was 10.59 U mg-1. The permeabilization of the S. fragilis IZ 275 cells was efficient.

Cheese whey is presented as an alternative for the production of ethanol to be a major source for growth of microorganisms, which catalyze lactose directly to ethanol and other products. Thus the aims of this study were to analyze the influence of nutrients in the cheese whey (15%w/v) fermentation by Saccharomyces fragilis IZ 275, to estimate the ethanol production and verify the repetition of the results of fermentation on a laboratory and pilot scale. Based on the results the nutrients, ammonium sulphate and yeast extract showed no significant difference at 5%, however, a positive ethanol productioin of 5.07% (w/v) and 5.43% (w/v), in laboratory and pilot scale, was respectively observed. In both kinetics, the ethanol yields were 5.6% (v/v), demonstrating that the use of deproteinized cheese whey for industrial fermentations is possible due to repetition of the results from laboratory to pilot scale, presenting as a way to reduce the pollution potential of this by-product, and at the same time to obtain value-added product.

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