Abstract
A defined minimal sporulation medium for Clostridium acetobutylicum P262, which produces high levels of solvents, is described. The overall sporulation sequence was similar to that of other endospore-forming bacteria. However, we observed a presporulation stage, during which swollen phase-bright cells which contained large amounts of granulose formed. During sporulation, the initiation of spore coat formation occurred before the onset of cortex formation. Other Clostridium strains tested showed marked variations in ability to grow and sporulate in various minimal media.