Evaluation of the Fermentative Capacity of CAT-1 and BB9 Strains and BB2 at Simulated Industrial Conditions.

The search for promising yeasts that surpass the fermentative capacity of commercial strains, such as CAT-1, is of great importance for industrial ethanol processes in the world. Two yeasts, BB2 and BB9, were evaluated in comparison to the industrial yeast CAT-1. The objective was to evaluate the performance profile of the three studied strains in terms of growth, substrate consumption, and metabolite formation, aiming to determine their behaviour in different media and pH conditions. The results showed that under cultivation conditions simulating the medium used in the industrial process (must at 22° Brix at pH 3.0) the highest ethanol productivity was 0.41 g L h for CAT-1, compared to 0.11 g L h and 0.16 g L h for and BB2, respectively. CAT-1 produced three times more ethanol in must at pH 3.0 (28.30 g L) and in mineral medium at pH 3.0 (29.17 g L) and 5.0 (30.70 g L) when compared to the value obtained in sugarcane must pH 3.0 (9.89 g L). It was concluded that CAT-1 was not limited by the variation in pH in the mineral medium due to its nutritional composition, guaranteeing better performance of the yeast even in the presence of stressors. Only CAT-1 expressed he constitutive invertase enzyme, which is responsible for hydrolysing the sucrose contained in the must.