Classifications of Bacteria
Bacteria are the smallest cellular organisms and are prokaryotes. They can be identified in three ways, judging their shape, whether they are Gram-positive or negative and the way they move.
– Sphere Shaped
– Rod Shaped
– Spiral Shaped
There are also differences other than shape, these include whether the bacteria is Gram-positive or Gram-negative. Gram-positive bacteria turn violet in colour when Gram stained, whereas Gram-negative bacteria absorb the red counter-stain because the size of the peptidoglycan (murein) layer. The Gram-positive bacerial peptidoglycan layer is between 20 and 80 nanometers wide compared with 7 to 8 with Gram-negative bacteria.
As the ‘gram’ part comes from the stain used by Hans Christian Gram it should always have a capital ‘G’.
Below is a set of slides which go beyond what we have covered so far. They cover growing bacteria, the lifecycle of bacteria and how a fermenter works.