Chapter V 

 PRESERVATION OF CULTURES 



Any mold that is valuable because it has been used in fundamental 

 research work, because it has been found useful in some industrial process, 

 or because it is a significant agent in some destructive or pathogenic situa- 

 tion should be preserved to insure its identity for subsequent use or refer- 

 ence. Identification by description will take the careful worker to the 

 group, species, and often to the variety as based upon morphology or some 

 conspicuous character, but the reidentification from description of the 

 exact organism used in a biochemical investigation or discovered in some 

 ecological situation is generally impossible. Culture collections have, 

 therefore, developed. The Centraalbureau voor Schimmelcultures (cited 

 by them as C.B.S.) at Baarn, Holland, the National Type Culture Collec- 

 tion in London, and the American Type Culture Collection at Washington 

 are well-known sources of such material. More recently established, but 

 containing a greater number of industrially important molds, is the culture 

 collection of the Northern Regional Research Laboratory (commonly 

 cited as N.R.R.L.) at Peoria, Illinois. The Aspergilli are especially well 

 represented, and contained in the collection are almost all of the species 

 considered in this manual, together with records which check the identify- 

 ing numbers of this collection against the records of the source collections* 

 which were brought into it. 



In undertaking a comparative study of the Aspergilli, or any other group 

 of molds, it is essential to maintain in a viable state a large number of 

 isolates representing diverse species and strains. By this means, it is often 

 possible to interpret current isolates and accessions in terms of historic 

 types and concepts. In maintaining such a collection of molds, the objec- 

 tive should be to preserve viability without growth or germination of 

 spores during the storage period. By so doing, the user can reasonably 

 expect to maintain his organism without variation, degeneration, or muta- 

 tion. A number of techniques can be employed to advantage, the more 

 useful of which will be considered in some detail with certain of their 

 advantages and limitations noted. 



* Currently contained in this collection are the molds formerly maintained by 

 Thorn and Church, and later by Thorn and Raper, in the United States Department 

 of Agriculture, Washington, D. C; many of the Mucorineae maintained by Dr. A. F. 

 Blakeslee for many years at the Carnegie Institution, Cold Spring Harbor, Long 

 Island, New York; a large number of miscellaneous forms from the Harvard Univer- 

 sity Collection initiated by Prof. R. Thaxter and more recently maintained by Dr. 

 D. H. Linder; and limited numbers of cultures from many other collaborators. 



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