Sensitivity of Escherichia Coli to Viral Nucleic Acid.

Cells of E. coli CT2 and CT20 become susceptible of infection by viral nucleic acids during growth in a hypertonic medium containing sucrose and polyvinylpyrrolidone. The competence for transfection arises in 2 to 3 hr after transfer to the hypertonic medium and reaches a plateau after about 5hr. Thymine starvation, which is known to induce envelope changes in E. coli, does not promote development of competence. Cellular competence is rather unstable at 37°C, while it is retained for several days at low temperature. Some properties of the DNA-transfection system are described.