ABSTRACT
We optimized the medium for recombinant dextransucrase expression in engineering strain Escherichia coli BL21 (DE3)/pET28-dexYG by an Orthogonal experiment. After the medium had been decided, we studied the effect of temperature, sucrose concentration and pH value on the yield. The results indicated that optimal conditions were adding IPTG of 0.25 mmol/L when OD600 reached 2.0 and cultivation lasted for 4 h at 25 degrees C. Under the selected medium and these conditions, the dextransucrase activity expressed by the engineering strain was high activity. Maximal activity reached 110.16 U/mL sucrose concentration effects the dextran yield grately. The results for dextransucrase expression would provide foundation for industrial application of dextransucrase.