Spore germination promoter of Dictyostelium discoideum excreted by Aerobacter aerogenes

The nutrient medium in which Aerobacter aerogenes was grown, contains a spore germination promoter (SGP) for the cellular slime mould Dictyostelium discoideum. SGP can cuase synchronous spore germination in a short time, and triggers the germination process in just a few minutes. Germination-promoting capacity of SGP decreases as it comes in contact with increasing number of spores. When spores activated by SGP are stored at 4 degrees C, they gradually return to the dormant state. SGP is comparatively heat-stable, but is unstable at pH above 10 or under 3.