BACTERIAL ENDOCYTOBIONTS INHABITING THE PEREINUCLEAR SPACE OF PROTISTA

Facultative bacterial endocytobionts of the perinuclear space in Cilio phora, Chrysophyta and Kinetoplastida (14 species in all) are describe d using the authors' data and excerpts from the literature. A morphome trical analysis of the bacteria indicates that they are commonly Gram- negative, rod-like particles with similar dimensions and morphology. T he bacteria of the nuclear envelope of paramecia do not have infectiou s capacity or killer traits. The killing capacity and infectivity of o ther perinuclear endocytobionts have not yet been determined. In light of the similar morphology of the bacteria and their location in the h ost cell it is possible that most of the endocytobionts are from a sin gle phyletic group. The types of endocytobiosis are considered with re spect to the evolution of the bacterium-host interaction.