Utilization of cell response under heat, chemical, and combined stresses for selective recovery of cytoplasmic beta-galactosidase from Escherichia coli cells.

The effective bioseparation process was developed by exploiting the cell response under heat, chemical, and combined stresses for selective recovery of cytoplasmic beta-galactosidase from Escherichia coli cells. At the observed optimal condition for heat stress (45 degrees C, 30 min) and that for chemical stress (20 mM Triton X-100, 5 mM EDTA, 30 min), E. coli cells were exposed to these stresses either simultaneously or sequentially. The operational sequence highly affected the yield and selectivity of the target recovery. Exposing the cells to the sequential stress (heating at 45 degrees C for more than 30 min after Triton X-100/EDTA treatment for 30 min) was found to be most effective for selective recovery of target beta-galactosidase among possible sequences.