Immunological detection of the GerA spore germination proteins in the spore integuments of Bacillus subtilis using scanning electron microscopy.

To clarify the molecular mechanisms that trigger spore germination of Bacillus subtilis, the location of GerA proteins (GerAA, GerAB and GerAC), which were reported to be putative gene products of a receptor for one of the germinants, L-alanine, was investigated by immunological techniques using anti-GerA peptide antibodies. Four antibodies were raised against the corresponding epitopes, two in GerAA, one in GerAB and the other in GerAC molecules. The binding of all four antibodies to the inner surface of the cortex-less spore coat fragments could be seen by scanning immunoelectron microscopy with colloidal gold particles. The result agreed with the fact, previously reported, that the colloidal gold particles were visualized just inside the spore coat layer by transmission immunoelectron microscopy using another anti-GerAB peptide antibody.