A major interest in the Setlow lab is trying to answer a number of fundamental questions about the mechanism of germination of spores of Bacillus species. These questions include: 1) how do the nutrient receptors to which binding of nutrient ligands triggers spore germination work; 2) do the three proteins encoded by individual germinant receptor operons physically interact; 3) do receptors that respond to different nutrients interact in some fashion; and 4) how does the spore's huge depot of dipicolinic acid (~10% of spore dry weight) leave the dormant spore in the first min of spore germination. Recent results using Bacillus subtilis spores that are relevant to the answers to these questions will be presented.