ANHYDROBIOSIS — A MODEL OF A 

 CRYPTOBIOTIC STAGE 



A. KOHN AND M. LION 



Department of Biophysics, Israel Institute for Biological Research, Ness-Ziona 



(Israel) 



The term anhydrobiosis, a state of ametabolic latent life due 

 to dehydration was introduced by Giard in 1894^ as an addition 

 to the terms osmobiosis, anoxybiosis, and cryobiosis. 



The process of lyophilization or freeze-drying discussed in 

 this lecture is actually a combination of cryobiosis, anoxybiosis 

 and anhydrobiosis, since the micro organisms are first frozen, 

 then oxygen, air and water are removed by vacuum and a 

 dehydrated viable product is obtained. 



The problems of anhydrobiosis in higher animals and plants 

 (rotifers, nematodes, fungi, seeds of plants) are the subject of 

 other lectures in this conference; some of them are treated by 

 Keilin in his Leeuwenhoek Lecture-. In large animals, the 

 maximal loss of water compatible with viability is about 92%, 

 while in bacteria the loss of 99.5% or more of water is still 

 compatible with continuing existence. Cryptobiosis in spore- 

 forming bacteria is treated in a separate lecture. 



In the field of anhydrobiosis of vegetative bacteria, much 

 information is available. In the National Type Culture Collection, 

 out of 2,700 strains which were dried over phosphorus pentoxide, 

 83 % remained viable after 14 years-^. Freeze-dried staphylococci, 

 pneumococci, streptococci and some Gram negative bacteria 

 were found to be viable after 17^ and 20 years^. Stamps showed 

 that bacteria dried in a desiccator for 2-3 days under reduced 

 pressure preserved their antigens and virulence for at least four 

 years {S. typhi, P. pestis, P. leptoseptica, E. rhusipathiae, S. 

 pyogenes, etc.). 



One of the latest papers on this subject has been published by 

 Feldmann", who tested 100 strains of 58 species of bacteria. The 

 bacteria were dried in vacuo, or freeze-dried in skim milk, and 



References p. 29 



