Effect of Different Variables on the Efficiency of the Baker's Yeast Cell Disruption Process to Obtain Alcohol Dehydrogenase Activity

Cell disruption process of dry baker's yeast was studied in this work to obtain maximum activity of alcohol dehydrogenase (ADH). Disruption by ultrasonication, glass beads, and combination of these two methods was compared. A 1.8-fold increase of ADH activity can be achieved by combining glass beads with ultrasonication in comparison to ultrasonication. To achieve maximum volume activity of ADH, the effect of different variables on the cell disruption process was investigated (time, glass bead diameter, mass of glass beads, and ultrasound amplitude). Using the Design-Expert© software, 2 4 factorial experimental design was performed. Two ultrasound probes were tested: MS 73 and KE 76. Optimal conditions (process variables) for cell disruption process were obtained. Optimal ADH activities after cell disruption with MS 73 and KE 76 probes were 1,890.9 and 1,531.7 U cm −3 , respectively. Necessary ultrasonication time and ultrasound amplitude should be at the maximum values in the investigated variable range (30 min and 62 %). Bead size should be at maximum (4 mm) when using MS 73 probe and at minimum (0.3 mm) when using KE 76 probe. Partial purification of the enzyme was carried out and it was kinetically characterized using several oxidation and reduction systems.