A FREEZE-FRACTURE STUDY ON THE MEMBRANE-ASSOCIATED PARTICLES OF AEROBICALLY AND ANAEROBICALLY GROWN ESCHERICHIA COLI

Abstract

Differences of membrane structures in E. coli cells between aerobically and anaerobically grown cells were studied by the freeze-fracture technique. Numerous particles were observed on the protoplasmic fracture face (PF-face) of both the aerobically and anaerobically grown cells. Most of the particles had a diameter of about 10 nm, with fluctuation of size from 5-20 nm. Homogenous and dense distribution of these particles was observed in the aerobic cells, while the distribution of the particles was rather sparse in the anaerobic cells. Average number of the particles on PF-face was 8.3 .times. 103/.mu.m2 in the aerobic cell and 3.0 .times. 103/.mu.m2 in the anaerobic cell. There were smooth areas lacking particles in the anaerobic cells. Exoplasmic fracture face contained few particles both in the aerobic and anaerobic cells.