The Internal Membranes of Caulobacter Crescentus

Abstract

The intracytoplasmic membranous structures previously observed in various caulobacter species by electron microscopy of thin sections were studied further by electron microscopy of whole organisms of C. crescentus negatively stained with phosphotungstate. The large complex meso-somes are intrusions of the cell membrane. They appeared, from their central location in dividing cells, to play a role in division. Smaller and less involuted intrusions of the membrane became abundant in oxygen-limited cells, which also had an abnormally high content of haem pigments. These smaller intrusions may therefore be a structural reflexion of an increased content in the membrane of components of the respiratory electron transport system. The membranous organelle which occurred at the site of stalk formation and appeared to be connected with the membranous core of the stalk was not penetrated by phosphotungstate, and therefore had an organization different from that of the mesosome.