Back to Microbes
In this unit, we do not focus on the life process of growth in particular organisms, but we do focus on the growth of a whole population of bacteria.

Growth of bacterial populations

Bacteria reproduce asexually by the process of binary fission. If conditions are ideal, they can split in two every 20-30 minutes. At first, the number of bacteria in the population increases slowly. But the more bacteria there are, the more reproduction is occurring and so the rate of growth increases. When growth is happening at a faster and faster rate like this, we call it exponential growth.


The growth of a bacterial population keeps getting faster and faster until one of the following things happen.
  • There is a shortage of food
  • There is a shortage of water
  • There is a shortage of oxygen (for aerobic bacteria)
  • There is too much heat produced
  • There are too many toxins produced

When the conditions stop being ideal, the exponential growth of the population will level out or decline.