THE ULTRASTRUCTURE OF STRESSED LEGIONELLA-PNEUMOPHILA

Legionellae are able to survive in natural environments which kill man y other organisms. The reason for this stress resistance is not well u nderstood nor have its morphological correlates been investigated. The ultrastructure of Legionella pneumophila subjected to stress by heat, acid and starvation, was studied by transmission electron microscopy. Heat-treated cells showed little change although cell shape tended to be distorted. Acid-treated cells showed severe shrinkage of cytoplasm ic contents. Starvation caused a reduction in cell size, and after 1 m onth of starvation cells became fragile, although viability was not re duced.