Sensitivity of Escherichia coli to Cold-Shock during the Logarithmic Growth Phase

Abstract

Cells removed at 10-min. intervals from the broth culture during the phases of increasing population were sensitive to cold-shock; cells from mature cultures were resistant. These data confirm the work of Sherman and Albus (1923, 1924). In additional expts. the culture was sampled less frequently and the cold-shocked sub-culture held continuously at 0[degree]C for a 6-day period: cells removed during the logarithmic growth were immediately sensitive; mature culture samples were not affected by the cold-shock and prolonged holding. Samples removed during the lag and early logarithmic growth periods became sensitive after being held at 0[degree]C for several hrs. The sensitivity to cold is evidently concerned with changes occurring within the cells as well as some stage of cell division. Data obtained support the contention of earlier workers that the growth curve proceeds in a step-like manner.