GLUCOAMYLASE PRODUCTION IN CONTINUOUS CULTURES OF ASPERGILLUS-NIGER WITH SPECIAL EMPHASIS ON GROWTH-PARAMETERS

Maltose-limited continuous culture of Aspergillus niger was carried ou t with potassium nitrate to investigate growth and glucoamylase format ion characteristics. Glucoamylase production was dependent on the spec ific growth rate. The maximal amount of glucoamylase (units/l and U/g dry weight) was obtained at mu = 0.08 h(-1), and the maximum specific rate of production (units/g/dry weight per hour) was at mu = 0.2 h(-1) . The maintenance coefficients (m(s) and m(ATP)) were higher than for some other fungi. Maximal growth yields on substrate, oxygen and ATP ( Y-xsm, Y-xO2m and Y-xam) were very efficient (high) and the value of Y -xam, which cannot exceed the theoretical maximal value, is obtained w hen a P/O ratio of 1:1 is assumed. This indicates that biomass formati on is energetically inexpensive and most of the expended energy has to be invested in the process of glucoamylase excretion.