370 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1963 



Penicillin, the first to be discovered, was derived from a blue- 

 green mold, Penicillium, commonly known from blue cheese or the 

 spoilage of citrus fruits, bread, moist tobacco, or leather. The anti- 

 biotic penicillin was discovered in 1929 by Alexander Fleming, of 

 St. Mary's Hospital, London. Its commercial production, however, 

 waited on a cooperative effort by American scientists, engineers, and 

 industrialists, akin to the concurrent pooling of energies to create the 

 atomic bomb. The great healer, penicillin, partially restored life 

 against the havoc of the great destroyer. 



In retrospect, the botanical aspects of the cooperative effort con- 

 cerned (1) selection and improvement of the mold, and (2) the 

 establishment of the most favorable conditions for growth of the 

 mold as a penicillin producer. In other words, there was a genetical 

 approach, aimed at obtaining superlative germ plasm, and an ecologi- 

 cal one, to provide it the best means of expression. 



Since Penicillium is lamentably sexless, the genetical program 

 could not exploit breeding procedures, as can be done with yeasts in 

 the fermentation business. It was necessary to resort to an exten- 

 sive selection process, in which literally thousands of molds from 

 soil samples w^ere tested for antibiotic (penicillin) yield. For this 

 purpose soil samples from various remote parts of the world were 

 flown by the military to Peoria, Illinois, the home of the federal 

 Northern Regional Research Laboratories, where the total program 

 was centered. As it chanced, the mold of choice resided right in 

 Peoria and was picked up via a spoiled cantaloupe by a laboratory 

 technician, affectionately called "Moldy Mary." This prize-winning 

 mold was identified by Drs. Raper and Thom as Penicillium 

 cJirysogenum. 



Now a new technique, characteristic of the dawning atomic era, 

 was brought into play to improve Penicillium chrysogenum. This 

 was radiation. Scientists set out to alter the genetical nature of the 

 mold spores by X-radiation and ultraviolet, something never at- 

 tempted before for practical purposes. These pioneer researchers 

 met with inordinate success almost at once. New strains of mold 

 were obtained which yielded as much as 500 times the penicillin of 

 the original isolate of Fleming. Incidentally, radiation is today a 

 choice means of strain improvement in molds used in industry. Each 

 corporation has its own carefully guarded organisms, although admit- 

 tedly the improvements are seldom of the magnitude attained in 

 Penicillium in the days of high drama when it was about to make 

 its debut. 



The great innovation on the environmental side was the submerged- 

 culture process. It happens that Penicillium^ and molds generally, 

 are avid users of oxygen and therefore grow only on the surface of 

 liquids. It seems ridiculous to us nowadays that initially Penicillium 



