Comparative study of pressure- and nutrient-induced germination of Bacillus subtilis spores

Germination experiments with specific germination mutants of Bacillus subtilis, including a newly isolated mutant affected in pressure-induced germination, suggest that a pressure of 100 MPa triggers the germination cascades that are induced by the nutrient germinant alanine (Ala) and by a mixture of asparagine, glucose, fructose, and potassium ions (AGFK), by activating the receptors for alanine and asparagine, GerA and GerB, respectively. As opposed to germination at 100 MPa, germination at 600 MPa apparently short-cuts at least part of the Ala- and AGFK-induced germination pathways. Inhibitors of nutrient-induced germination (HgCl(2) and Nalpha-P-tosyl-L-arginine methyl ester) also inhibit pressure-induced germination at 600 MPa, suggesting that germination at 600 MPa involves activation of a true physiological germination pathway and is therefore not merely a physico-chemical process in which water is forced into the spore protoplast.