What is the optimal growth temperature for Escherichia coli?

The optimal growth temperature for Escherichia coli is 37 degrees Celsius. This temperature closely matches the warm-blooded animals whose intestines commonly harbor the bacterium, allowing many E. coli strains to grow rapidly and efficiently.

E. coli is a facultative anaerobe: it can use oxygen when available but can also grow without it. The species was described by Theodor Escherich in 1885 after he studied bacteria from infant intestines. Most strains are harmless gut residents, although some cause foodborne illness, urinary infections, or other diseases.

The 37°C figure is a standard optimum, not an absolute rule for every strain or laboratory condition. Some laboratory strains grow at cooler temperatures, while certain strains can multiply at temperatures approaching 49°C. The distractor 42°C may seem plausible because it is associated with heat-shock experiments, but it is above the usual optimum for routine growth. At 25°C, E. coli can grow, but generally more slowly.