Abstract
A. pullulans converts starch into biomass by the production of glucoamylase (1,4-.alpha.-D-glucan glucohydrolase EC 3.2.1.3) only. The enzyme synthesis apparently did not depend on substrate induction; maximal enzyme activity, however, occurred after 48 h growth in YNB [yeast N base] medium containing soluble starch as the sole C source. The enzyme had the following characteristics, as determined in the cell-free culture broth: optimal pH 5.75; optimal temperature 50.degree. C; complete heart inactivation after 10 min at 60.degree. C; apparent optimal reaction time 120 min.