Pestis and the People
Plague Forms
Pestis Effects



Domain: Bacteria

Kingdom: Prokaryotae

Phylum: Proteobacteria

Class: Gammaproteobacteria

Order: Enterobacteriales

Family: Enterobacteriaceae

Genus: Yersinia

Species: Yersinia pestis

Photo: Centre for Health Protection

Yersinia pestis is unicellular, placing it in the Bacteria domain.  It is classified as a Prokaryotae because of its absence of a nuclear membrane and DNA that is not organized into chromosomes.  Y pestis fits in the Proteobacteria phylum because it is gram negative and a facultative anaerobe (can live in absence or presence of oxygen.)  Being a purple sulfur bacteria places it in the Gammaproteobacteria class, while it is considered in the Enterobacteriaceae family because it lacks oxidase and is a non-spore forming bacteria.

Y. pestis is considered a chemoorganotroph, which simply means it depends on organic material for energy and carbon.  It's shape is a small, straight rod.  Y. pestis is nonmotile and it's most favorable temperature is from 28-30C.

The sequencing of the entire chromosome of Yersinia pestis is currently being explored at the Sanger Center in Cambridge (UK).

Phylogenetic Tree of Yersinia pestis




Kristi Taylor