Life is the vital source of all living things, either plant or animals, big or small. Whatever their size may be, life is essentially important to all living things.
If any organism must survived, it must be able to respond to change in it environment, must be able to feed, able to exchange gas with it environment, and reproduction, these are all essential part of life.
So also the bacteria possess all these characteristic of life, in other to obtain a normal growth of bacteria in the laboratory, nutrient media is necessary. The knowledge of the metabolism is important. Metabolism in bacteria is as a result of chemical interaction that take place spontaneously in the bacteria, but the reaction is speed up to completion in short time by protein substance called enzyme. Reactions that take place do to metabolic reaction are in two processes which are;
These reactions occur as a result of broken down of complex substance to simpler one which is used by the bacteria.
this reaction result in the formation of complex substance from the simple one in the living organism when the need arise.
In catabolism, energy is needed to bring the reaction to completion. This energy is obtained from broken down of molecular substance. The energy requires may be 1000nm in singles cells for it transfer. For the identification of bacteria, is due to action of enzyme on their specific substrate. As it was stated previously, oxygen is require for the growth of some bacteria, but it is obvious that the effect of oxygen in the growth of bacteria cell depend either the oxygen is used for final hydrogen acceptor in the respiratory processes, which is confer to aerobic respiration. It seem to be that all bacteria require some carbon dioxide (CO2) from the atmosphere and most of the bacteria growth rapidly when there is concentration of CO2 ranging from 5-10% despite the availability of the requirement of their oxygen.