Comparative study on the cell wall structure of protein-producing Bacillus brevis

Among eight strains of protein-producing Bacillus brevis, three morphological groups have been identified according to the structure of the cell walls. Cell wall consisting of a peptidoglycanlayer Two-layered cell wall consisting of a peptidoglycan-layer and an S-layer Three-layered cell wall consisting of a peptidoglycan-layer and two S-layers Group I and group II cell walls have not been described yet for protein-producing bacteria. The S-layers observed in this study all had hexagonal symmetry and lattice constants of approximately 18 nm. The immunological relation between the S-layer proteins of the newly isolated B. brevis strains and those of B. brevis 47 has been examined using antisera against both S-layer-proteins of B. brevis 47. S-layers from protein-producing B. brevis strains, which were adjacent to the peptidoglycan-layer, were similar to each other, whether they were the outermost cell wall layer (group II) or not (group III). However, no similarity was found between these layers and the outermost S-layer of B. brevis 47 (group III).