Adsorption of phage λ DNA onEscherichia coli cells treated with Ca++ ions and on frozen and thawed bacteria

Investigation of adsorption of biologically active tritiated phage λ DNA onEscherichia coli cells treated with Ca++ ions in the cold and on frozenthawed bacteria revealed no correlation between the increase in adsorption and the efficiency of transfection. The level of adsorption of infectious DNA, for instance, was unchanged by freezing and thawing theE. coli cells, whereas after treatment with Ca++ ions in the cold it was increased tenfold; the level of transfection of phage λ DNA on both types of recipients was the same.