Sequential protein production and cell disruption was studied using. E
. coli double-lysogen, P90c/(lambda LHL1,phi 434). The induction of th
e first prophage lambda HL1 to produce beta-galactosidase by the tempe
rature increase was followed by the induction of the second prophage p
hi 434 by the W-irradiation to lyze the cell. The optimum operating co
nditions for the UV-irradiation were sought to yield the maximum cell
lysis.