We know that certain extremophiles thrive at subzero temperatures, happily multiplying in sheets of ice and deep in frozen caves and lakes. But there’s a lower limit to almost everything, and researchers at the British Antarctic Survey wanted to know what that limit was for single-celled organisms at low temperatures. At what point do organisms become unable to reproduce? The answer is -20ºC, or -4ºF.
To test this, the researchers put single cell organisms in a watery environment and lowered the temperature to see when the organisms became vitrified, or unable to reproduce, which the scientists considered to be no longer living.
The researchers determined that negative 20 degrees Celsius is the lowest temperature the organisms could reproduce before becoming vitrified.
Vitrification is different from cell death in that an organism will typically continue living, but be unable to propagate. At the end of the organism’s life, there’s no offspring to replace it. For this reason, deep freezing food is considered an effective method of preservation; bacteria and mold cannot multiply and will only live as long as a typical lifespan allows, thereby reducing the risk of infection or disease in humans.