ENHANCEMENT OF PRODUCTION OF CLONED GLUCOAMYLASE UNDER CONDITIONS OF LOW AERATION FROM RECOMBINANT YEAST USING A SUC2 PROMOTER

The effect of aeration rate on the production of cloned glucoamylase i n a recombinant yeast was investigated. This system consisted of Sacch aromyces cerevisiae transformed with the 2 mu-based plasmid YEpSUCSTA which contains the SUC2 promoter, the STA signal sequence, and the STA structural gene. In contrast to typical yeast expression reports, hig h production of cloned glucoamylase was achieved at low aeration level (0.3 vvm). The recombinant yeast grown at 0.3 vvm aeration produced m ore glucoamylase (0.94 units/ml) than when grown at 0.0 vvm, 0.6 vvm, or 0.9 vvm (9.4, 1.4, and 3.1 times more, respectively). A high dissol ved oxygen level early in the cultivation was important for cell growt h and a low dissolved oxygen level during the production stage was imp ortant for glucoamylase production. In large scale processes for the p roduction of recombinant proteins, the maintenance of aeration and dis solved oxygen at high levels is difficult and expensive. In this work, we have evaluated the coordination of oxygen level with growth and pr otein production and developed optimal conditions. Since a low aeratio n rate was optimal, our results demonstrate that the method described at the laboratory scale should be successfully applied at an industria l scale. (C) 1997 Elsevier Science Ltd.