ALPHA-AMYLASE PRODUCTION IN AQUEOUS 2-PHASE SYSTEMS WITH BACILLUS-SUBTILIS

The production of alpha -amylase by Bacillus subtilis has been studied in repeated batch fermentations in aqueous two-phase systems. In a phase system composed of PEG 600, 8% (w/w), PEG 3350, 5% (w/w)/Dextran T 500, 2% (w/w), 82% of the enzyme partitioned to the top phase. The enzyme concentration in the top phase reached 0. 85-1. 35 U ml** minus **1 during the fermentations compared with 0. 58 U ml** minus **1 in the reference fermentation. In the phase system composed of PEG 3350, 9% (w/w)/Dextran T 500, 2% (w/w), 73% of the enzyme partitioned to the top phase. However, the enzyme concentration in this phase system reached only 0. 35 U ml** minus **1 in the top phase. The bacterial cells were microscopically observed to partition totally to the bottom phase in the aqueous two-phase system used. The results are discussed in relation to recirculation of cells by immobilizing to a solid matrix.