In order to understand what’s included in the microbial world, it is important to understand how all organisms are labeled and organized. The science of classifying organisms into groups according to common characteristics is called taxonomy.
Organisms are placed into groups with common traits or features. From there they are ranked from general to specific. In bacterial taxonomy, the most commonly used ranks or levels from most to least specific are: species, genera, families, orders, classes, phyla, and kingdoms.
Species are the basic taxonomic group in bacterial taxonomy. Groups of species are then collected into genera. So, for example, E.Coli, which is a bacterial species has a lot of strains, and each type has its own characteristics and functions. For example, certain strains of E. Coli are harmful and can cause foodborne illness while others help the body create Vitamin K! Therefore it is important to understand both the species and the strain of any particular bacterium.
When we perform the genetic sequencing of your microbiome, we identify the bacteria on the strain level, which is the most specific. Groups of strains belong to the same species; groups of species together are considered a genus; groups of genus together belong to the same family; groups of families belong to the same order; same orders belong to the same class which belong to the same phyla and belong to the same kingdom.
In the table below, you can see an example of the taxonomy of a specific bacteria in comparison to a human being (homo sapien):
| Taxonomy | Human (Homo Sapien) | Faecalibacterium prausnitzii |
| Kingdom | Animals | Bacteria |
| Phylum | Chordata | Firmicutes |
| Class | Mammalia | Clostridia |
| Order | Primates | Clostridiales |
| Family | Hominidae | Clostridiaceae |
| Genus | Homo | Faecalibacterium |
| Species | H. Sapiens | F. prausnitzii |
| Strain | gcf000154385 |