In this article we will discuss about the process of respiration in bacteria.
Like other living things bacteria respire. They oxidize food materials present in the cytoplasm to obtain energy. Most bacteria make use of the free oxygen of the atmosphere or oxygen dissolved in the liquid environment.
They are called the aerobes or aerobic bacteria. They are so called because they can live only in the presence of free oxygen. Free oxygen is necessary for their respiration.
The free oxygen diffuses in through the bacterial cell wall and oxidizes the food materials present in the cytoplasm. The reaction takes place in two steps. The, first step includes the oxidation of food materials with the removal of pairs of hydrogen atoms.
The second step comprises the oxidation of hydrogen atoms by oxygen with the liberation of energy. The released energy is captured in ATP (Adenosine triphosphate) formed from Adenosine diphosphate (ADP) and phosphoric acid.
The oxidation of food thus results in the production of CO2, H2O and formation of ATP. Car bon dioxide diffuses to the exterior through the body surface. The important feature of respiration is not so much the gaseous exchange but the formation of ATP.
It is a compound in the body of a living organism which captures and stores the energy released in respiration which otherwise would simply have produced heat.
The energy entrapped in ATP is used gradually as the need arises to run many reactions in the bacterial cell.
Aerpbic respiration is represented by the following equation:
Anaerobes or Anaerobic bacteria:
There are a considerable number of bacteria which are able to live and multiply in the absence of free oxygen. In fact they perish in the presence of free oxygen. These peculiar bacteria obtain oxygen for their respiration from organic compounds such as sugar.
They are called the anaerobes or anaerobic bacteria. A good example of this type are the bacteria which decompose glucose to form alcohol and carbon dioxide.
Anaerobic respiration is accomplished by the secretion of certain oxidizing enzymes. The latter bring about breakdown of foods. It is followed by the rearrangement of atoms within the organic molecule.
Certain molecular groups take up the contained oxygen from the others. The amount of energy available from this type of respiration is much less than when free oxygen is used.
This is because glucose molecules are not completely oxidised. Much of the energy stored in glucose remains in alcohol. Some of the anaerobic bacteria do not require free oxygen. They are, actually poisoned or killed by its presence.
They can live and multiply only in the absence of free oxygen. Examples are syphilis and tetanus bacteria. Such bacteria are called obligate anaerobes.
There are other anaerobic bacteria which can live and grow whether oxygen is present or not. They are called the facultative anaerobes.