CONTROLLED LYSIS OF ESCHERICHIA-COLI DOUBLE-LYSOGEN OF BACTERIOPHAGESLAMBDA-HL1 AND PHI-434

A novel phage double-lysogen was developed to produce an intracellular protein and disrupt the host cell in the same reactor. Using this dou ble-lysogen, we could simplify the recovering processes without cell h arvest and disruption. Construction of the double-lysogen is based on the fact that a lysogen of a phage can be superinfected by another pha ge with different immunity. The single-lysogen of Escherichia coli, P9 0c/lambda HL1, was superinfected with bacteriophage phi 434 to produce a double-lysogen, in which phage genomes from each phage coexisted in the host chromosome. Two different inducers were used to induce the d ouble-lysogen to produce a protein and to lyse the host cell. The firs t phage genome, lambda HL1, the prophage of the original lysogen, cont aining the temperature sensitive cI(857), lacZ and defective Q genes w as induced by increasing temperature to produce beta-galactosidase, an intracellular reporter protein. The overproduction of beta-galactosid ase was carried out without experiencing the cell lysis due to the def ective Q gene. After the temperature shift, the second prophage from t he lysogen MS21/phi 434 was induced by mitomycin C or ultra-violet lig ht to lyse the cell. The lysis of the cell releases the intracellular protein to the outer space. The cell lysis was confirmed by the decrea se of cell density and the increase of the extracellular activity of b eta-galactosidase at the same time.