Bacteria reproduce by binary fission. Once a bacterium reaches maximum size, the genetic material is copied and the cell splits in two. Each new bacteria grows then splits in two. If there plenty of food, moisture and warmth, bacteria can reproduce every 20 minutes.
The above graph shows a typical bacterial growth curve. At the start of the graph there is only a small number of bacteria. They reproduce by binary fission so numbers increase slowly (2 to 4 to 8 to 16). However each time the number doubles, so the bacterial population increases very quickly (5000 to 10000 etc). A fast rate of reproduction continues until a factor (lack of food, space, water, build up of toxins, cooler temperature) limits bacteria reproduction, shown by the curve leveling off. The end curve shows a reduction because of the death of bacteria due to the limiting condition.
One way to reduce food poisoning is to maintain food in conditions that limit bacterial reproduction. eg cool temperatures in the fridge don't kill bacteria but reduce reproduction.
