A microbe is a small living thing too tiny to be seen by the naked eye and includes bacteria, fungi and viruses. Among their destructive actions is causing diseases in human beings and their livestock or plants, destruction of food by causing decomposition which might lead to hunger and other related calamities. Despite this destructive consequences, microbes are also known to have advantageous actions like helping in sewerage treatment, microbes found in the gastro-intestinal tract help in maintaining a good environment for digestion to take place. Microbes also help in ecological balance by causing decomposition of dead matter hence conserve the environment.
Important factor defining the desert biomes is its tendency to lose water by evaporation, and this potential for water loss exceeds the annual rainfall and defines what organism can live in there.