14 



MICROBIAL CELL WALLS 



higher red, brown, and green algae and plants. ^^ The types 

 of structures detected in microbial walls are summarized in 

 Table 1. Multilayered walls are encountered more fre- 



TABLE 1 



Physical Properties of Microbial Cell Walls Revealed by Electron 



Microscopy 



Type of Fine Structure 



Algae 



Chlorella pyrenoidosa 



Fungi 



Phycomyces 

 Neurospora crassa 



Yeast 



Saccharomyces cerevisiae 



Bacteria 



Escherichia coli 



Halohacterium 

 Spirillum sp. 

 Spirillum serpens 

 Rhodospirillum rubrum 

 Lampropedia hyalina 



Bacillus megaterium 

 Staphylococcus aureus 

 Streptococcus faecalis 



Double-layered, microfibrillar 

 polysaccharide (fibers at 90° to 

 one another) + amorphous matrix 



Microfibrillar components 



Multilayered wall, microfibrillar 

 layer (fibers 90° to one another); 

 fibers oriented around bud scars 



Multilayered (2 electron dense: 

 1 electron transparent layers); 

 macromolecules not visible in 

 intact wall 



Multilayered structures with spheri- 

 cal macromolecules (80-120 A di- 

 ameter) visible; hexagonal packing 



Structure giving crystalline lattice 



appearance 

 Fibrous? 

 Amorphous structure— thickened 



bands at zone of wall formation 



References 24 to 40. 



