Plasmid formation after lambda bacteriophage infection of Escherichia coli-Salmonella typhosa hybrids

Defective phage lambdadg, when present in certain Salmonella typhosa hybrids, could be eliminated with acridine orange or ethidium bromide treatment. The lambdadg deoxyribonucleic acid could be separated from the S. typhosa host deoxyribonucleic acid as a distinctly covalently closed molecule.