Germination of wild-type, gerD, and gerF spores with l-valine (A) or AGFK (B). Spores of strains PS533 (wild-type) (○), FB62 (ΔgerD) (●), and PS3301 (ΔgerF) (▵) were prepared and purified, and spore germination with either 10 mM l-valine (A) or 10 mM l-asparagine plus GFK (B) was followed by measuring DPA release fluorometrically in relative fluorescence units (RFU) as described in Materials and Methods.