Anisotropic crystal growth of the S-layer of Bacillus sphaericus CCM 2177 at the air/water interface

Abstract

The isolated subunits of the crystalline bacterial cell surface layer (S-layer) from Bacillus sphaericus CCM 2177 show an inherent ability to reassemble at the air/water interface. The most important parameter for the recrystallization process is the calcium concentration in the subphase. Depending on this parameter, a broad spectrum of crystal morphologies ranging from tenuous, fractal-like structures to large monocrystalline patches was found. Cross-correlation averaging was used for identifying the position and orientation of morphological units in the crystal lattice and for improving the signal-to-noise ratio of fine image details. Under optimized recrystallization conditions, large perfectly crystalline monolayers were formed. Such large monolayers are the basis for using S-layers as patterning structures in molecular nanotechnology.