Soil contains more genera and species of microorganisms than other microbial habitats. This may be due to the fact that it contains a lot of nutrients and usually retains some liquid within its pore spaces. Some species of these microorganisms are present in large numbers while some are otherwise not, probably because the factors necessary for the survival and growth of these microorganisms are not evenly distributed naturally across the depth of the lithosphere. Microorganisms are highly adaptable to varying conditions both genetically and physiologically, because they have been in existence for over 3.5 billion years