Abstract
The time required for the germination of anaerobic spores following single cell isolation is extremely variable, as may be seen from the records of 2 strictly anaerobic bacteria, Cl. acetobutylicum and Cl. Pasteurianum. Spores were picked with the modified Chambers micromanipulator and were immediately transferred to suitable culture media, beef-peptone-glucose agar, corn mash, milk, Hall's brain mash, or Speakman's synthetic medium. Sterile vaseline was layered onto the medium to maintain anaerobic conditions and to prevent evaporation during long incubation. From 100 isolations of Cl. acetobutylicum and 14 of Cl. Pasteurianum the 6 cultures as given in the table were obtained.
Why should a spore lie dormant for 222 days or, for that matter, for 11 days before germination? Conditions of temperature, available food, and anaerobiosis were favorable during the entire period. As far as we know there was no change which might have acted as the final stimulus to germination. It was suggested that perhaps a spore, like a seed, needed a period of ripening after being set free from its mother sporangium. However, a review of the ages of spores when picked does not bear this out. No. 70 (4) with a dormancy of only 19 days came from a free spore in an agar colony 96 hours old while No. 105 (3) with the extreme dormancy of 222 days came from a stock culture in corn mash 1 year old.
Even the extreme germination time in the table is far shorter than the extreme recently reported by Dickson. 1 He found growth in a thermal death point experiment on Cl. botulinum 72 months after heating. However, his Cl. botulinum spores may have been injured by heating while those of Cl. acetobutylicum and Cl. Pasteurianum picked directly from stock cultures should be of unimpaired vitality.
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