FIG. 3.

Negatively stained preparations of monolayer crystallites formed by recrystallization of the soluble (monomeric and/or oligomeric) S-layer protein from B. stearothermophilus PV72/p2 on poly-l-lysine-coated EM grids. (A) Small crystallites were formed by the S-layer protein isolated from biomass grown at a low specific growth rate (10 μg of SCWP/mg of S-layer protein). (B) Significantly larger monolayer patches were obtained with the S-layer protein from biomass cultivated at a high specific growth rate (30 μg of SCWP/mg of S-layer protein). In both cases, the S-layer subunits had bound with their charge-neutral outer face. Arrows indicate base vectors. Bars, 200 nm.