OPTIMAL DISRUPTION METHODS FOR THE SELECTIVE RECOVERY OF BETA-GALACTOSIDASE FROM ESCHERICHIA-COLI

A method for optimization of the cell disruption process in order to i mprove the release selectivity and efficiency of a target intracellula r enzyme was investigated. The cell concentration as measured by optic al density was found to be an effective measure for the determination of the degree of cell disruption. Based on a kinetic analysis of the c ell disruption process, generalized operational parameters were found to apply depending on the specific energy supplied. Generalized values for the disruption rate constant K-C and the release rate constant fo r each enzyme K-i (i=1, 2, ...) were well correlated with the cell wal l strength as a function of the disruptive stress and with the intrace llular location of the enzyme, respectively. Determined values of the release selectivity, K-i/K-T, were found to be an indication of the in tracellular location of the enzyme. The disruption medium was modified by the addition of polyethylene glycol 1540 to enhance the release se lectivity of the target beta-galactosidase from Escherichia coli ML308 . The addition of polyethylene glycol from 0 to 5% was found to increa se the release selectivity of beta-galactosidase from a value of 1.2 t o 3.0. The disruption condition (specific energy input) was optimized to give both the higher yield and selectivity.