A gene having a DNA sequence complemtentary to that of the glucoamylase polypeptide mRNA from a fungal Species, preferably Aspergillus awamori, is prepared. The mRNA is an approximately 2.2 kilobase poly a RNA obtain from fungal cells grown under conditions of glucoamylase induction. Reverse transcription of the mRNA provides a glucoamylase probe used to identify genomic digest fragments containing glucoamylase gene regions, which are sequenced to locate the introns and exons. The genomic fragments are spliced together to form a gene having a DNA sequence with altered or deleted introns which codes for fungal glucoamylase protein and is capable, when correctly combined with a cleaved DNA expression vector, of expressing a non-native protein having glucoamylase enzyme activity upon transformation of a host organism by the vector. The host organism is preferably a bacterium or a yeast.; The transformed host organism may be used to produce ethanol.