Bacteria are prokaryotic and unicellular beings.

Prokaryotic beings are classified into two big groups: archaebacteria and bacteria

Bacteria are responsible for the decomposition process at the end of food chains and food webs; in this process, they also liberate utile gases and nutrients for other living beings.

Bacteria can be found in various environments throughout the planet. There are bacteria in the air, in fresh water, on the surface, in the intermediate depth and on the bottom of the sea, in soils, in our skin and practically in all terrestrial environmen

According to their necessity of oxygen bacteria are classified into anaerobic (those that survive without oxygen) and aerobic (those that do not survive without oxygen).