24 MISCELLANEOUS PUBLICATION 9 5 5, U.S. DEPT. OF AGRICULTURE 



Among the special collections of micro-organisms is that of Bacillus 

 strains assembled from all over the world by N. R. Smith for his 

 studies leading to the monographing of the genus. Another famous 

 collection is the actinomycete strains assembled by S. A. Waksman at 

 the Institute of Microbiology, Rutgers University, New Brunswick, 

 N.J. Often such specialized collections are more complete in the lim- 

 ited area they cover than can be found in any of the general collections. 

 Usually cultures can be obtained from special collections upon request, 

 although one should recognize the burden upon a curator in time and 

 equipment required to provide transfers. 



In addition, all major fermentation companies have large collections 

 of micro-organisms, but their scope, size, and contents are not revealed. 

 Usually no cultures are distributed except the few strains deposited 

 with general collections for assay of their products or for patent 

 applications. 



In using strains of micro-organisms from culture collections, several 

 procedures should be followed after the culture is received. Adequate 

 stocks should be prepared to maintain the strain and from which to 

 prepare inoculum for experimental work. The culture's identity 

 should always be verified. The culture should be studied to see that it 

 is free of all contaminants, contains no aberrant strains resulting from 

 mutation, and is in a vigorous, growing condition. If research on a 

 particular strain is published, the author should clearly state the source 

 of his culture and the number under which he received it. Some pub- 

 lished research has little value, because no reference is made to the 

 source of the culture ; consequently, results of other published research 

 on the same strain cannot be correlated with new information. 



MAINTENANCE OF CULTURES "\ 



The procedure by which both the life and the taxonomic, physiologic, 

 and morphologic integrity of a culture are conserved is called mainte- 

 nance. Culture maintenance is the concern of everyone who works 

 with living cultures, especially the personnel of culture collections. 

 A prerequisite to success in maintaining cultures is a knowledge of 

 the micro-organisms to be conserved. Some bacterial physiologists 

 concentrate on one or a few strains or species of related bacteria and 

 need relatively little information to maintain their stock cultures. 

 At the other extreme are curators of large culture collections who need 

 a broad knowledge about many kinds of micro-organisms in order to 

 conserve successfully their collections so that they may distribute 

 authentic, viable cultures. These collections sometimes include bac- 

 teria, actinomycetes, yeasts, molds, and even algae, viruses, and 

 protozoa. 



Every viable culture has a life expectancy within which effective 

 action must be taken if viability is to be retained. With certain strains 

 of micro-organisms maintained in lyophil (freeze dried), the life 

 expectancy may be a matter of years and no immediate action is re- 

 quired. The life expectancy of Lactobacillus leichmannii Bergey et 

 al. in stab or deep broth culture may not exceed a week. With this 

 species and with other fastidious types, not only must action be taken 

 soon after receipt of the culture but it must be repeated at weekly in- 



