Epulopiscium Fishelsoni - Reproduction

Reproduction

Perhaps the most intriguing aspect of the bacteria is its unusual, almost viviparous reproductive cycle. Unlike most bacteria, which undergo binary fission, Epulopiscium reproduces exclusively through an unusual form of sporulation in which anywhere from one to twelve daughter cells are grown inside of the parent cell, until the cell eventually lyses and the new bacteria burst through the cell wall. Although sporulation is common among other bacteria (such as Bacillus subtilis), it is a desperation measure brought about by overcrowding or starvation, rather than a standard form of reproduction. Also, the daughter cells in standard sporulation are usually dormant, while new Epulopiscium cells are active.

This form of reproduction has been observed in other large gut symbionts (Metabacterium polyspora), which are phylogenetically related to Epulopiscium. Since sporulation affords bacteria much more protection from the outside environment than binary fission, it is thought that the evolution of this unusual life cycle may be in order to allow transfer of the bacteria from one host to another, and also provide protection during reproduction from the harsh environment of the digestive system.