Synthesis and excretion of alpha-amylase is investigated in batch cultures of Escherichia coli JM103[pMK57] (vgb(-)) and E. coil JM103[pMK79] (vgb(+)). While total production and excretion of alpha-amylase were promoted in Luria broth (LB) (excretion being as high as 87%), cell-mass-specific production of the enzyme was promoted in M9 in bioreactor cultures and in LB in shake flask cultures. Low aeration and agitation rates and presence of starch were conducive to alpha-amylase synthesis in E. coil JM103[pMK79]. Two-stage bioreactor operating strategies that will improve alpha-amylase production are proposed. The potential of these strategies is demonstrated via two-stage shake flask cultures.