The invention is directed to non-natural yeast able to secrete significant amounts of glucoamylase into a fermentation media. The glucoamylase can promote degradation of starch material generating glucose for fermentation to a desired bioproduct, such as ethanol. The glucoamylase can be provided in the form of a glucoamylase fusion protein having secretion signal that is: derived from at least AA 1-19 of SEQ ID NO: 73, (ii) an amino acid sequence of at least AA 1-19 of SEQ ID NO: 74, (iii) SEQ ID NO: 77 (An aa), (iv) SEQ ID NO: 75 (Sc IV), (v) SEQ ID NO: 76 (Gg LZ), or (vi) SEQ ID NO: 78(Hs SA).