ABSTRACT
Broadly, the terrestrial environments comprise approximately 28% of the Earth’s surface, including a great degree of variation, ranging from tropical rainforests to desert areas. Moreover, each terrestrial area can be classified into a number of major biomes such as desert, tundra, and grasslands (BeraldiCampesi 2013). They are arguably the most physically complex of all microbial environments, due to the structural organization of soil particles that can produce a spatially heterogeneous habitat for various organisms, characterized by different levels of substrates and nutrients, oxygen concentration, water content, and pH (Ladd et al. 1996).
