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Survey of Bacteria



There are millions of species of bacteria, and they can be grouped based on shared characteristics. A common approach to this grouping is numerical taxonomy, in which organisms are grouped according to mathematical methods. Numerical taxonomy uses characteristics such as genetic homology, or shared heritable material, to measure relatedness between organisms. Bacteria are more difficult to classify than more complex organisms because they have simple structures, short generation times, and because the fossil record gives little information about them. Bacteria are often classified according to their shape, biochemical makeup, methods of nutrition, metabolic processes, and other characteristics that can be determined using simple lab tests.

At A Glance

  • Bacteria are difficult to classify under traditional taxonomic rules because of their short generation times and simple structures.
  • Bacteria are grouped according to shared characteristics, especially by using numerical taxonomy, which groups organisms according to mathematical methods based on character states.
  • Bacteria are classified based on physical traits such as morphology, arrangement of cells, and cell wall content.
  • Bacteria are classified based on their metabolic needs for specific organic and inorganic materials.