 Escherichia coli encompasses an enormous population of bacteria that exhibit a very high degree of both genetic and phenotypic diversity . Genome sequencing of a large number of isolates of E. coli and related bacteria shows that a taxonomic reclassification would be desirable . However , this has not been done , largely due to its medical importance , and E. coli remains one of the most diverse bacterial species : only 20 % of the genes in a typical E. coli genome is shared among all strains . 
