The production of an amylase from starch by Aspergillus niger is often performed in a fed batch fermenter. This is due to the reason that

• fed-batch reactor can be used to minimize starch concentrations and prevent a. niger from fermenting
• fed-batch reactor can be used to minimize starch concentrations and thus reduce the viscosity of the medium
• continuous reactor can be used to minimize starch concentrations and their inhibitory effects
• all of the above