Extracellular production of α-amylase during fed-batch cultivation of recombinant Escherichia coli using pulsed electric field

In this study, extracellular release of recombinant α-amylase from Escherichia coli HB101/pHI301A by high-voltage pulsed electric field (PEF) was demonstrated during fed-batch cultivation. A continuous PEF treatment from the beginning of cultivation caused a decrease in cell growth rate and productivity of α-amylase, although a small quantity of extracellular α-amylase was detected in the culture supernatant. On the other hand, when PEF (12 kV, 3 Hz) was applied intermittently (each for 30 min with an interval of 30 min) from the beginning of stationary phase, the amount of α-amylase released was about 30% of the total amount of α-amylase that was produced in the cells. The release ratio and the total amount of α-amylase released were higher than that of batch cultivation. Suitable PEF treatment can be useful for easy and effective extracellular release of periplasmic proteins by fed-batch cultivation of recombinant E. coli.