Quantifying microbial lag phenomena due to a sudden rise in temperature: a systematic macroscopic study

Area of Science:

• Microbiology
• Microbial Physiology
• Bacterial Growth Dynamics

Background:

• The microbial lag phase is a poorly understood phenomenon.
• Previous studies often confounded multiple factors affecting lag phase duration.
• Systematic investigation of environmental triggers is needed.

Purpose of the Study:

• To systematically investigate the effect of sudden temperature shifts on the lag phase of exponentially growing Escherichia coli.
• To characterize the influence of temperature shift amplitude, pre-shift temperature, and post-shift temperature on lag phase occurrence and duration.

Main Methods:

• Experiments utilized a computer-controlled bioreactor for precise control of Escherichia coli K12 MG1655 growth conditions (aerobic, BHI broth).
• Systematic variation of temperature shift amplitude, pre-shift, and post-shift temperatures.
• Lag phase duration quantified using a common growth model.

Main Results:

• Temperature shifts induced lag phases of approximately one hour, depending on the tested factors.
• Lag/no-lag behavior correlated with the physiological temperature range and temperature rise amplitude.
• The lower boundary of the normal physiological temperature range for E. coli was identified between 22.78 and 23.86°C.

Conclusions:

• The lower temperature boundary for E. coli growth is a transition zone, not an absolute cutoff.
• Temperature shift amplitude and proximity to the physiological range boundary influence lag phase induction.
• The mechanism triggering the lag phase exhibits biological variability.