Freeze-fracture Observations of the Cell Walls and Peribacillary Substances of Various Mycobacteria

Abstract

Ultrastructure of the cell wall and peribacillary substances of various mycobacteria (32 strains of 18 species) grown in vitro was studied by a freeze-fracture technique. Peribacillary substances differed in shape among species and even among strains of the same species, and were classified into five types: (1) amorphous substances; (2) multi-layered sheaths with no filamentous units; (3) structures composed of filaments of 2-4 nm diameter, which were further classified into three subtypes according to the arrangement of the filaments; (4) helical fibres; and (5) single fibres, or networks of fibrous structures, with no visible substructures. No strains revealed peribacillary structures resembling those of uncultivable Mycobacterium leprae. These results have implications for the mechanism of freeze-fracturing in mycobacterial walls.

Freeze‐fracture observations of Corynebacterium glutamicum: the occurrence of an outer membrane‐like structure and the influence of temperature on the cytoplasmic membrane

“…3b). It should be noticed that the structures of the outer membrane-like layer described here seem to be suitable markers for investigations on the localized growth of the cell wall (see also TAKEO et al 1984).…”

Widespread Abundance of Functional Bacterial Amyloid in Mycolata and Other Gram-Positive Bacteria

“…TEM images revealed that FuBA fibrils that were 9 nm wide were predominantly close to or integrated into the cell wall, whereas a minor fraction was distant from the cells. Several authors have used freeze fracture electron microscopy to show that the outer capsule surrounding intraphagosomal M. avium and M. lepraemurium consists of a multilaminar structure (41,46). Each lamella of the M. avium coat is made up of parallel straight fibrils that are 5 nm wide.…”

The outer parts of the mycobacterial envelope as permeability barriers

“…In some cases, including Mycobacterium leprae (42) and M.lepraemurium (43), the zone consists partly of defined glycolipids (phenolic glycolipid and mycoside C, respectively) which are produced in massive amounts by these species. There is evidence that such lipids are also part of the superficial layer in other species (44,45), but the amounts are smaller. In other cases such as M.tuberculosis no equivalent lipids are produced, while strains of M.avium and M.intracellulare unable to produce glycolipids of this type still form an electron transparent zone inside infected cells (46).…”