A tough, dormant form some bacteria produce that can survive cooking and other harsh conditions, then grow again when conditions improve.
It is a tough, dormant form some bacteria make to survive harsh conditions like heat and drying. The spore can outlast ordinary cooking and then germinate back into an active, multiplying bacterium when conditions become favourable again.
Because they survive cooking, spore-forming bacteria can grow after food is cooked if it is cooled slowly or held warm. This is why proper cooling and hot-holding, not just cooking, are needed to keep food safe.
Clostridium perfringens, Clostridium botulinum and Bacillus cereus are the main spore-forming bacteria of concern in food. Each is linked to problems that arise when cooked food is not cooled or held at safe temperatures.
Not always. Reheating can kill growing cells, but some spore formers produce heat-stable toxins once they have multiplied, and those toxins survive reheating. Keeping numbers low through rapid cooling is the reliable control.
By cooling cooked food quickly using the two-stage cooling times, holding hot food at 60 degrees or above, reheating rapidly, and avoiding long periods in the temperature danger zone. Shallow containers and prompt refrigeration help.