Summary Statements

Abstract

In the early 1970’s there were no more than three or four laboratories actively working with bacterial S-layers (Murray, Chapter 1). Few microbiologists recognized their existence as cell envelope components and the best possible electron microscopy was required for their detection. Then, they were not always called S-layers but were instead named paracrystalline arrays, regularly structured layers (RS-layers), planar crystalline layers, or surface layers (S-layers). They had been detected only on a few species of Acinetobacter, Bacillus, Clostridium and Spirillum (Aquaspirillum). Yet, those few scientists who worked in the S-layer field not only recognized their fragile beauty and symmetry but also understood that, since they were metabolically expensive devices for each bacterium to synthesize, S-layers must have an important function.