The production of acidic alpha-amylase by a novel acidophilic bacterium Bacillus acidicola TSAS1 was optimized in submerged fermentation using statistical approaches. The process parameters that significantly affected alpha-amylase production (starch, K2HPO4, inoculum size and temperature) were identified by Plackett and Burman design. The optimum levels of the significant variables as determined using central composite design of response surface methodology are starch (2.75%), K2HPO4 (0.01%), inoculum size [2% (v/v) containing 1.9 x 10(8) CFU ml(-1)], and temperature (33 degrees C). An overall 2.4 and 2.9-fold increase in enzyme production has been attained in batch and fed-batch fermentations in the laboratory fermentor, respectively. (C) 2011, The Society for Biotechnology, Japan. All rights reserved.