Aerobic and anaerobic bacteria
can be identified by growing them in liquid culture:
1: Obligate aerobic
(oxygen-needing) bacteria gather at the top of the test tube in order to absorb maximal amount of oxygen.
2: Obligate anaerobic
bacteria gather at the bottom to avoid oxygen.
bacteria gather mostly at the top, since aerobic respiration is the most beneficial one; but as lack of oxygen does not hurt them, they can be found all along the test tube.
gather at the upper part of the test tube but not at the top. They require oxygen but at a low concentration.
bacteria are not affected at all by oxygen, and they are evenly spread along the test tube.
A microaerophile is a microorganism that requires oxygen to survive, but requires environments containing lower levels of oxygen than are present in the atmosphere (~20% concentration). Many microphiles are also capnophiles, as they require an elevated concentration of carbon dioxide. In the laboratory they can be easily cultivated in a candle jar. A candle jar is a container into which a lit candle is introduced before sealing the container's airtight lid. The candle's flame burns until extinguished by oxygen deprivation, which creates a carbon dioxide-rich, oxygen-poor atmosphere in the jar.
See also 
External links