up vote 3 down vote accepted. $\pi$ is the name of the constant relating the diameter and circumferance of a circle. It's a definition, a particular constant that we thought deserved a name. $e$ happens to be the name of a constant from a particular limit. Like $\pi$, we named it because we thought it would be useful. In Physics, many, many constants have names. Gravitational constants, expansional constants, electrical constants, etc. Each is useful, but somewhat arbitrarily chosen.
Bacteria: The Monera Kingdom Bacteria are classified into two groups: Eubacteria (true bacteria) and Archaebacteria (Ancient Bacteria). They are autotrophic. 28-1 Chapter 28: Microbiology. 28-2 Viruses Viruses are noncellular, nonliving particles and therefore are not included in the classification scheme.
In that system, bacteria are members of the domain Bacteria and phylum is the rank below domain as the rank kingdom is disused at present in bacterial taxonomy.In this classification scheme, Bacteria is (unofficially) subdivided into over 29 phyla with representatives cultured in a lab.any major clades of bacteria that exist but cannot currently be cultured are known solely via metagenomics and are called candidate phyla. If these are included, the number of phyla is 52 or higher. Therefore, the number of major phyla has increased from 12 identifiable lineages in 1987, to 52 as of 2003.