CULTIVATION AND PRESERVATION OF PENICILLIA 



81 



for asepsis are exercised. It is kno^vn that this method of culture preser- 

 vation is commonly practiced in the laboratories of penicillin manufactur- 

 ing industries. Some Avorkers .successfully maintain cultures of penicillin 

 producing molds in dry sand or a mixture of sand and talc. In the ab- 

 sence of any colloidal material to serve as a possible protective coating 



Fig. 21. Lyophil apparatus, table model, a, Manifold; b, Bruner-type vacuum 

 gauge; c, thermometer; d, lyophil preparations in final stages of desiccation; e, Dewar 

 flask containing a water-vapor trap immersed in COo-ice and methyl cellosolve; /, 

 vacuum pump; g, insulated freezing bath; h, vacuum tester; z, oxygen -gas torch. 

 (After Raper and Alexander, Mycologia, 37, 1945). 



for the spores, it is difficult to see how the sand or talc could exert any 

 favorable effect. Members of the Penicillium chrysogemmi series are 

 knoAvn to be especially long-lived in culture, and it is possible that equally 

 good results might be obtained by preserving a mass of spores in a dry 

 state in the absence of any type of extender. 



Preservation under Oil: During recent years several mycologists have 

 adopted a method of culture preservation wherein a strain is permitted to 

 reach a suitable stage of development and is then covered with a layer of 



