Spore Formation among the Anaerobic Bacteria

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Abstract
Investigations were initiated to determine more precisely the conditions under which clostridia produced spores. Effects of variation of pH, Eh, temp., variation in conc. of peptone, meat extract, carbohydrates and different carbohydrates were considered. In a 2/3-strength Difco nutrient agar medium buffered with phosphates, the optimum pH for sporulation of C. sporogenes was between 6.9 and 7.4. Sporulation was inhibited at or below pH 6.1, almost completely, for at least the first 4 days of anaerobic incubation. Increase in peptone beyond a necessary minimum did not greatly affect rate of formation of spores; variation in meat extract content had even less influence, spores being formed in almost the complete absence of the ingredient. 1% fermentable sugar in dilute nutrient agar inhibited spore formation; 1% lactose stimulated spore formation. In an originally alkaline medium, presence of 1% fermentable sugar inhibited sporulation only in media which contained small conc. of available N. Results indicated a fundamental relationship between decrease in metabolic activity from its maximum and the onset of sporulation. Spore formation seemed a natural phenomenon in the developmental cycle of C. sporogenes, and occurred unless the vegetative cells were prevented from forming spores.

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