The purpose of this investigation was to study the effect of Streptomyces erumpens cells immobilized in various matrices, i.e., agar-agar, polyacrylamide, and luffa (Luffa cylindrica L.) sponge for production of alpha-amylase. Luffa sponge was found to be 21% and 51% more effective in enzyme yield than agar-agar and polyacrylamide, respectively. Response surface methodology was used to evaluate the effect of three main variables, i.e., incubation period, pH, and temperature on enzyme production with immobilized luffa cells. The experimental results showed that the optimum incubation period, pH, and temperature were 36h, 6.0, and 50 degrees C, respectively. The repeated batch fermentation of immobilized cells in shake flasks showed that S. erumpens cells were more or less equally physiologically active on the support even after three cycles of fermentation (3,830-3,575 units). The application of S. erumpens crude enzyme in liquefying cassava starch was studied. The maximum hydrolysis of cassava starch (85%) was obtained with the application of 4ml (15,200 units) of crude enzyme after 5 h of incubation.