TECHNOLOGY FOCUS - BIOTECHNOLOGY - Preferred Enzyme: (Ia) further comprises a linker amino acid sequence selected from SEQ ID NOs 26-29 or a sequence differing from one of these sequences by no more than 10 positions. The catalytic module of (Ia) preferably has at least 80, 90 or 95% homology to SEQ ID NO:8 or SEQ ID NO:30. The carbohydrate binding domain of (Ia) preferably has at least 60, 70, 80 or 90% homology to a sequence selected from SEQ ID NOs: 9-25. (Ia) preferably comprises (Ib) where the catalytic domain comprises amino acids 21-498 of SEQ ID NO:40 or a sequence having at least 70% homology to this sequence.(Ib) preferably comprises a substitution in one or more positions selected from 81, 158, 161, 163, 164, 175, 176, 177, 264, 266, 466, 468 and 470. (Ib) preferably comprises one or more substitutions selected from Q81R, K158D, K158V, S161D, S161N, Q163S, Q163A, D164S, Y175W, E176D, D177N, N264K, N264E, M266L, G466D, D468S and M470D. (Ib) preferably comprises one or more substitutions selected from K158V, S161N, Q163A, D164S, N264K, M266L, G466D, D468S, and M470D. (Ib) preferably comprises one or more substitutions selected from Q81R, K158V, S161N, Q163A, D164S, Y175W, E176D, D177N, N264K, M266L, G466D, D468S and N470D.(II) preferably comprises one or more of the following substitutions: G33A, I136K, S74A, D75Y, E77D, P120A, I153D, D154N, W155Y, D156E, N157D, L158Q, Q162E, E166L, T169N, I170T, E199K, E199L, D232L, N233D, N235D, L238Y, D239T, W256Y, Q257P, E331Q, S336A, D339K, D339N, V340D and Y342A. The variant preferably comprises an alteration at one or more of positions 31, 74, 89, 209, 245, 348, 378, 383, 386, 387, 405, 448, and 480. The variant preferably comprises one or more of the substitutions: N31D, S74A, Y89D, E209L, Y245V, D348K, D378A, K383A, P386A, I387F, I405V, N448S and N480R, and may comprise all of these substitutions.Preferred Method: In liquefying starch the treated starch is preferably contacted with a yeast to produce fuel or potable ethanol. The treated starch is fermented into a product such as citric acid, monosodium glutamate, gluconic acid, sodium gluconate, calcium gluconate, potassium gluconate, glucono delta lactone, sodium erythorbate, itaconic acid, lactic acid, gluconic acid, ketones, amino acids, glutamic acid (sodium monoglutaminate), penicillin, tetracycline, enzymes, vitamins, such as riboflavin, B12, beta-carotene or hormones. The starch slurry is contacted with a polypeptide comprising a carbohydrate binding module, but no catalytic module.Preferred Cell: (V) is from a fungus, bacteria, plant or mammal. EXAMPLE - The cDNA of Aspergillus niger acid stable alpha-amylase was obtained. PCR reaction was performed using the cDNA as template, with primers having sequences such as 5'-tttggatccaccatgagattatcgacttcgagtctcttc-3' and 5'-tttactagtagcagcagcagttgtggtcgtggttgttc-3', to introduce a BamHI site and SpeI site, respectively. The amplified DNA fragment of 1.5 kb was cut by SpeI and BamHI and ligated into pHUda381 digested by SpeI and BamHI to create the expression plasmid pHUda387. The plasmid pHUda387 was introduced into A. niger. The transformed organism was cultivated in non-selective YPG medium at 32 degrees C for 16 hours on a rotary shaker. The cells were collected by filtering, washed with potassium chloride (0.6 M) and resuspended in potassium chloride (0.6 M) containing beta-glucanase product. The suspension was incubated at 32 degrees C until protoplasts were formed. SPTC (1 ml) was added and the protoplast suspension was incubated for 30 minutes at 37 degrees C. After the addition of 50 degrees C Cove top agarose (10 ml), the reaction was poured onto Cove agar plates and the plates were incubated at 32 degrees C. After 5 days, the transformants were selected from the Cove medium. The selected transformants were inoculated in MLC media and cultivated at 30 degrees C for 2 days. The supernatant was obtained by centrifugation, in which acid stable alpha-amylase activity was determined.