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Microorganisms in food

4. Binary fission




Bacteria multiply by simple cell devision, which means one bacterial cell splits into two cells. This is called binary fission. Bacteria can carry out binary fission once every 20.-30 min as long as they have enough nutrients and moisture,  and the temperature is suitable. That means, the number of bacteria can increase very rapidly.

Example:

  • the bacteria divide every 20 min
  • number of bacteria = 2n (whereby n = the number of rounds of devision)

after 3h (= 180 min): 180/20 = 9  => n = 9 rounds of devision

number of bacteria = 29 => 512 or 5,12 x 102

after 8 hours (= 480 min): 480/20 = 24  => n = 24 rounds of devision

number of bacteria = 224 => 16,777 216 or 1,678 x 107


Watch the following animation of bacterial growth over the timespan of 8 hours in fullscreen mode: