Study of starch degradation by yeasts during fermentation for using in animal feed.

Sixteen amylolytic yeasts, drawn from culture collections or isolated from different environments, were used in the present study. Experiments were performed to evaluate the starch degradation due to exocellular activity. The culture media of growth was optimized to find the maximum activity, and some strains produced an extracellular amylolytic enzyme when cultured in presence of starch in the medium. On the other hand, one yeast showed activity in cell extract when cultured under varying conditions in a bench bioreactor; this strain would thus be suitable for use as an animal feed supplement, both as a source of proteins and nucleic acids and in terms of its amylolytic activity.