Bacteria consist of only a single cell, of a small size (around mm), discovered thanks to the microscope.
Bacteria live on or in just about every material and environment : on Earth from soil to water to air and under any conditions of pH, temperature and oxygenation.
Bacteria can heavily modify the physico chemical conditions of the environment where they live, forming a biofilm due to their metabolism at the surface of the material :
- modification of pH (some can lead to the formation of acids such as sulphur acid for example)
- modification of the oxygen concentration
- production of sulphur…
