Glucose-stat and pH-stat control strategies were employed in order to culture a recombinant E. coli XL1 Blue to produce a fusion protein of sweet potato sporamin (SPA) and glutathione S-transferase (GST) from the recombinant E. coli XL1 Blue. Cell densities up to 25 g l(-1) and 28.9 mg fusion protein (GST-SPA) g(-1) cell dry weight (CDW) was achieved from a fed-batch fermentation controlled by glucose-stat strategy. A pH-stat control fermentation using glycerol as a carbon source gave E. coli up to 27 g l(-1) and 31.5 mg GST-SPA g(-1) CDW. Additionally, a pH-stat control strategy using glucose as a carbon source gave E. coli up to 15 g l(-1) and about 22.7 mg g(-1) CDW of GST-SPA.