Glucoamylase production in batch, chemostat and fed-batch cultivations by an industrial strain of Aspergillus niger

The Aspergillus niger strain BO-1 was grown in batch, continuous (chemostat ) and fed-batch cultivations in order to study the production of the extrac ellular enzyme glucoamylase under different growth conditions. In the pH ra nge 2.5-6.0, the specific glucoamylase productivity and the specific growth rate of the fungus were independent of pH when grown in batch cultivations . The specific glucoamylase productivity increased linearly with the specif ic growth rate in the range 0-0.1 h(-1) and was constant in the range 0.1-0 .2 h(-1) Maltose and maltodextrin were non-inducing carbon sources compared to glucose, and the maximum specific growth rate was 0.19 +/- 0.02 h(-1) i rrespective of whether glucose or maltose was the carbon source. In fed-bat ch cultivations, glucoamylase titres of up to 6.5 g 1(-1) were obtained eve n though the strain contained only one copy of the glaA gene.