Controlled Lysis of Escherichia coli Double-Lysogen of Bacteriophage HL1 and 434

초록

A novel phage double-lysogen was developed to produce an intracellular protein and disrupt the host cell in the same reactor. Using this double-lysogen, we could simplify the recovering processes without cell harvest and disruption. Construction of the double-lysogen is based on the fact that a lysogen of a phage can be superinfected by another phage with different immunity. The single-lysogen of Escherichia coli, P90C/lambdaHL1, was superinfected with bacteriophage phi434 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 double-lysogen to produce a protein and to lyse the host cell. The first phage genome, lambdaHL1, the prophage of the original lysogen, containing the temperture sensitive cI857, lacZ and defective Q genes was induced by increasing temperature to produce beta-galactosidase, an intracellular reporter protein. The overproduction of beta-galactosidase was carried out without experiencing the cell lysis due to the defective Q gene. After the temperature shift, the second prophage from the lysogen MS21/phi434 was induced by mitomycin C or ultra-violet light to lyse the cell. The lysis of the cell releases theintracellular protein to the outer space. The cell lysis was confirmed by the decrease of cell density and the increase of the extracellular activity of beta-galactosidase at the same time.