Protein and ribonucleic acid syntheses in heat-damaged and heat-killed Escherichia coli.

Protein and ribonucleic acid (RNA) syntheses were measured in both lethally injured and thermally damaged viable cells after heating at lethal temperatures. Immediately after heating, cells were incubated in growth media containing either [14C]leucine or [3H]uracil. The labeled cells were subsequently treated with penicillin. Viable cells were shown to lyse, and the intact nonviable cells were collected by centrifugation. The results showed that after heating, protein and RNA synthesis were reinitiated in the penicillin-sensitive cell population, but there was no detectable protein or RNA synthesis in the heat-killed cells which were resistant to penicillin. The lack of protein or RNA synthesis in lethally damaged cells during the entire recovery period may be interpreted to reflect the lethal thermal damage.