EFFECT OF CULTURE FILTRATES ON SPOROGENESIS IN A SPECIES OF CLOSTRIDIUM

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Abstract
A variant strain of the Clostridium species, putrefactive anaerobe No. 3679 (PA 3679) designated as PA 3679h was used. When growth in liquid media was interrupted by heating or by removal of the cells before the medium was exhausted, followed by reinoculation of the filtrate at a low level, sporulation was significantly greater than when the original culture was allowed to grow without interruption. When spent filtrates of cultures of PA 3679h in 2% tryptic digest of casein (trypticase BBL) were refortified with 2 mg of trypticase/ml of spent broth, 60-90% sporulation occurred within 48 hours after reinoculation and incubation at 37C. A maximum of 40% sporulation occurred in fresh medium containing 6% trypticase. Thiamine was the only vitamin which en- hanced spore production when added to fresh medium. Addition of 0.1 [mu]g thiamine/ml to the fresh 2% trypticase medium allowed incipient sporulation but not maturation of the spores. Addition of 0.1 /[mu]g/ml thiamine to 4% trypticase broth allowed increased sporulation proportional to the increase in total population. A titration of the sporo-genic property of spent medium showed that sporulation was proportional to the concentration of the spent medium through 80% of the original concentration. When the number of generations of growth in the spent medium was controlled by the size of the inoculum, at least 4 generations were required in the single strength refortified spent medium but only 1 generation in the double strength spent medium to elicit the sporogenic effect. The filtrates of other organisms were also more sporogenic for PA 3679h than were their corresponding fresh media when added to 2% trypticase broth. Evidence presented indicates that the spent medium contains a substance (s) not present in fresh medium which enhances sporulation.
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