**2. Habitat of** *E. coli*

*Escherichia coli* can live on a wide variety of substrates. The availability of nutrients within the intestine of host species determines *E. coli* niche. The (GI) tract of humans and many other warm-blooded animals is the principal niche for *E. coli*. It cycles between two major habitats-warm-blooded animal intestines and the

**Figure 1.** *Structure of E. coli [6].*

Escherichia coli*: An Overview of Main Characteristics DOI: http://dx.doi.org/10.5772/intechopen.105508*

environment (water, sediment, and soil), which is considerably different in terms of physical conditions, the range, and quantity of nutrients availability. *E. coli* form a mutual relationship with its host. *E. coli* in the colon synthesizes K and B complex vitamins and protects the GI tract against colonization with pathogenic microbes, while the host offers an ecological niche and nutrients. *E. coli* is the most common type of facultative anaerobes in the intestine, accounting for around 0.1% of the gut microbiota [13]*. E. coli* can also be found in hotter conditions, such as on the edge of hot springs and on-ground meats due to slaughterhouse processing [14].
