Our intestines are long, and they contain a big load of live bacterial microorganisms — approximately 100 trillion of them at any one time.
These microbes comprise a diverse array of strains and species. Collectively, we know it as our gut microbiota, microbiome or microflora.
We have both our small and large intestines. As their environments are markedly different, different strains and species will tend to dominate the populations in those different regions.
For example, Lactobacillus species are predominantly found in the small intestine, while Bifidobacterium species tend to prefer being in the large intestine. Also, different strains and species will possess different adherence capabilities to the mucus linings of our intestines.