Abstract
Both Cl. butyricum and Cl. acetobutylicum did not produce enough spores in several media which have been reported as sporulation media for the anaerobes up to the present, while high percentages of sporulation in both organisms were observed within 32 hours in the medium containing glucose, 1.0 per cent; yeast extract, 0.5 per cent; peptone, 0.5 per cent; adjusted to pH 6.0.
The effects of concentration of medium, glucose, yeast extract, peptone, temperature, pH, oxygen, and strain difference on sporulation in both anaerobes have been studied using the above medium as a basal one.
Depression of spore formation occurred in diluted media in both Clostridium, especially, in Cl. acetobutylicum. It was caused by the lack of carbon and nitrogen sources in Cl. butyricum, whereas yeast extracts was a limitting factor in Cl. acetobutylicum. This fact suggested that growth factors such as biotin, thiamin and p-aminobenzoic acid were exacting for growth and sporulation in the latter anaerobes.
Being different from many cases of usual spore-forming bacteria, optimum pH for sporogenesis in both organisms was at pH 6.0 in acid medium, but coincided with optimal pH for growth.
Optimum temperature for sporulation as well as for growth was 37°C in both species.
Spore yields of Cl. butyricum were independent of presence of oxygen, while oxygen inhibited spore production of Cl. acetobutylicum.
Differences of ability to sporulate among the strains of both species were very significant respectively. For instance, sporulations above 80 per cent in some strain, but below several per cent in another strain were observed.
