NOVELTY - New glucoamylase variant (P1) comprises: amino acid substitutions at specific positions in a glucoamylase having specific amino acid sequence, or equivalent positions in a parent glucoamylase, where the glucoamylase variant has at least 80% sequence identity with the specific glucoamylase or parent glucoamylase.    USE - For producing a glucoamylase composition, which is useful for converting starch by hydrolyzing starch, for fermenting an alcohol, and for producing high glucose syrup (claimed). The alcohol produced by using glucoamylases in fermentation is ethanol and can be used as source of fuel or for alcoholic consumption.    ADVANTAGE - The glucoamylase variants (P1) exhibit increased thermostability, and/or exhibits increased specific activity, as compared to the parent glucoamylase, such as Trichoderma reesei glucoamylase (TrGA). The glucoamylase variants contain amino acid substitutions within either the catalytic domain or starch binding domain. The glucoamylase variants provide higher rates of starch hydrolysis at low substrate concentrations as compared to the parent glucoamylase, such as have higher Vmax or lower Km than a parent glucoamylase when tested under the same conditions e.g. variant glucoamylase has higher Vmax at 25-70 degrees C. Thermostability is measured as % residual activity after incubation for 1 hour at 64 degrees C in NaAc buffer pH 4.5, where under these conditions, TrGA has residual activity of 15-44% due to day-to-day variation as compared to the initial activity before incubation. Thus, the variants with increased thermostability have a residual activity that is 1 to at least 50% more than that of the parent (after incubation for 1 hour at 64 degrees C in NaAc buffer pH 4.5); further retain at least about 50, 60, 70, 75, 80, 85, 90, 92, 95, 96, 97, 98, or 99% enzymatic activity after exposure to altered temperatures over a given time period e.g. at least 60 to 300 minutes; have increased thermal stability compared to parent glucoamylase at selected temperatures in the range of 40-80 degrees C and at a pH of 4-6; and have increased thermal stability at lower temperature at 20-50 degrees C compared to the parent glucoamylase. The increased specific activity of glucoamylase variants as determined using ethanol assay shows performance index (PI) of greater than 1 compared to parent TrGA PI, where the PI for variant glucoamylase is 1-4.9 and the variant has 1-5 fold higher specific activity than the parent glucoamylase. The variants with improved thermostability and/or specific activity can significantly improve efficiency of glucose and fuel ethanol production from corn starch.    DETAILED DESCRIPTION - New glucoamylase variant (P1) comprises: amino acid substitutions corresponding to positions 61, 417, 431, and 539; 43, 417, 431, 535, and 539; or 73, 503, and 563, of a defined amino acid sequence of a glucoamylase containing 612 amino acids (SEQ ID NO:2) as given in the specification, or equivalent positions in a parent glucoamylase, where the glucoamylase variant has at least 80% sequence identity with a defined amino acid sequence of the glucoamylase containing 632 amino acids (SEQ ID NO:1) as given in the specification or the (SEQ ID NO:2), or the parent glucoamylase. INDEPENDENT CLAIMS are included for the following:    (1) a polynucleotide (N1) encoding the glucoamylase variant (P1);    (2) a vector (V1) comprising: the polynucleotide (N1);    (3) a host cell (C1) comprising: the vector (V1);    (4) method (M1) for producing the glucoamylase variant (P1); and    (5) an enzyme composition (C2) comprising: the glucoamylase variant (P1).