Bacteria live on teeth and in the crevices of gums, colonies are called plaque. Early colonisers e.g. strep, work commensally to enable later species of bacteria to inhabit the cavity. It is important to note, within plaque, there is a different, low pH and anaerobic environment and the bacteria inhabiting have adapted to inhabit it.
The early colonizers of teeth (strep) bind secrete polysaccharides and bind to the resulting sugar coated surface. Later colonisers (fusobacteria) bind to surface proteins on existing bacteria, this the early colonizers 'recruit' the later ones.

Adaptation of oral bacteria to challenging environments is a factor. The early colonizers have to endure pH3-4, thus they have developed acid tolerance mechanisms. Late colonisation of bacteria are present in an anoxic environment, both early (facultative) and late are anaerobes, but this two step mechanism allows for late colonisation by construction of an anaerobic environment.

Acid tolerance - low membrane permeability to protons; export of protons via proton pump; export of lactic acid.

	Created by Austin Davies over 10 years ago

Lecture 11 - medical micro