A recombinant form of the sweet-tasting protein thaumatin has been produced in the filamentous fungus Aspergillus niger var. awamori. Expression cassettes containing a synthetic gene encoding thaumatin II were prepared and used to transform Aspergillus niger var, awamori strain NRRL312. Several fungal strains capable of synthesizing and secreting thaumatin into the culture medium were generated, and their production capabilities were determined, first in shake flasks and later in a laboratory fermenter. We report the expression and secretion of thaumatin in concentrations of 5-7 mg/l. This recombinant thaumatin is sweet.