Death rate during the exponential growth of E. coli

TL;DR

This study measures the mortality rate of E. coli during exponential growth, revealing a small but significant death rate that was previously overlooked due to rapid bacterial proliferation.

Contribution

It provides the first direct measurements of E. coli mortality during exponential growth using flow cytometry, confirming the existence of a measurable death rate.

Findings

Detected a small but significant mortality rate during exponential growth

Provided estimates of mortality rate variability over time

Confirmed mortality rate increases from early exponential to stationary phase

Abstract

So fast is the growth of a culture of E. coli that it led researchers to overlook a possible death rate. As a matter of fact, the experiments done in the first half of the 20th century were unable to detect any mortality. It is only at the beginning of the 21th century that positive evidence emerged which confirmed the existence of a sizeable (albeit small) mortality. In the present paper this mortality was measured at successive 45mn time intervals from early exponential growth into the stationary phase. Done with a flow cytometer, the successive measurements of the ratio dead/living also provided an estimate of the standard deviation of the mortality rate. In a forthcoming experiment we are planning to focus more closely on the stationary phase in order to find out if its mortality rate is lower or higher than in the exponential phase.