text: charles thom charles thom ( november 11 , 1872 – may 24 , 1956 ) was an american microbiologist and mycologist . born and raised in illinois , he received his phd from the university of missouri , the first such degree awarded by that institution . he was best known for his work on the microbiology of dairy products and soil fungi , and in particular his research into the genera aspergillus and penicillium . his work influenced the establishment of standards for food handling and processing in the usa . he pioneered the use of culture media to grow microorganisms , and , with food chemist james n. currie , developed a process to mass - produce citric acid using aspergillus . thom played an important role in the development of penicillin in world war ii . early life thom was born in , illinois in 1872 , the fifth of six boys . his parents were angus sutherland thom and louisa ( ) thom , scottish / irish farmers who had settled in illinois shortly before the american civil war . charles thom was raised in a strongly religious household ; his father was an elder in the presbyterian church . thom upheld presbyterian values throughout his life , kept active in church affairs , and became a staunch prohibitionist . his early years spent working on his father 's farm instilled the value of a strong work ethic , and first - hand knowledge of agricultural practices that would prove useful in his later career . after graduating from high school , thom attended lake forest academy , a preparatory institution for college , in 1889 . he earned a bachelor 's degree from lake forest college in 1895 . the next year he spent as a science teacher in a danville high school , before returning to lake forest college to receive his master 's degree in 1897 . in 1899 , working under the supervision of howard ayers , he received his phd from the university of missouri on the topic of fertilization in the ferns and adiantum . this was the first doctorate awarded by that institution . thom married ethel winifred slater in 1906 , with whom he had three children ( one died during childbirth ) . ethel thom died in october 1942 , shortly before his retirement . in 1944 he remarried , to charlotte j. bayles , with whom he lived until her death . thom died two years after charlotte at his home in port jefferson , new york , on may 24 , 1956 . career in 1902 , thom went to study with george f. atkinson at cornell university ; two colleagues included benjamin and herbert , who both later became noted botanists . two years later , he accepted a position as dairy mycologist , working with herbert william conn , in charge of " cheese investigations " at the storrs agricultural experiment station in connecticut . he remained in this institution — a branch of the u.s. department of agriculture ( usda ) — holding various research and administrative positions , until his retirement in 1942 . during his employment there , thom investigated the process of cheese ripening and sought to understand the composition of the microbiological flora required for imparting certain flavors on cheeses . through this work he isolated and identified the fungi penicillium and penicillium . in 1914 , thom became the chief of the microbiological laboratory at the usda bureau of chemistry , where his job was to study problems with the handling and processing of foods , and to enforce the pure food and drug act , a united states federal law that mandated federal inspection of food products . known for his dedication to maintaining high standards in the food industry , he relished arguing court cases " in defense of sanitary practices in the handling and processing of perishable foods " . in one noted case involving the adulteration of tomato catsup , he presented partially rotten tomatoes to the jury , and , concluding his testimony , asked them " should the american people have to eat these in their catsup ? " during his time at the usda , thom became a world authority on the genera aspergillus and penicillium . thom pioneered the technique of using defined , reproducible culture media to grow microorganisms ; most of the taxa he described are still valid today . together with margaret b. church , thom maintained collections of fungus cultures for the american type culture collection , established in 1925 . in 1929 , a year after discovering penicillin , alexander fleming published a well - known paper in which he identified the mold penicillium rubrum as the one responsible for creating the drug . harold succeeded in growing the organism on a simple culture medium , but could not isolate the penicillin produced by the mold when grown this way . with thom 's assistance , they correctly identified the organism as penicillium and , in 1941 , developed a method to scale up production at the department of agriculture 's northern regional research laboratory in peoria , illinois , which ultimately resulted in an inexpensive supply of the drug . thom 's work with the food chemist james n. currie in 1916 – 17 enabled them to develop a process to mass - produce citric acid using aspergillus , and a few years later , the first large - scale mold fermentation factory had been established in brooklyn , new york . this early work ultimately led to the department of agriculture 's establishing four regional research laboratories in 1938 that were devoted to industrial mold . thom held his job with the bureau of chemistry until 1927 , when the position was abolished . he was then appointed principal mycologist of the division of soil microbiology for the newly created bureau of chemistry and soils . in a few years , thom became known as an authority on soil microbiology , and was often invited to present papers at national and international meetings . in one of thom 's important contributions to the field , he led the research group responsible for advances that enabled the control of cotton root rot , which at the time was a major problem in the southwestern united states . in collaboration with his protégé kenneth raper , they published the manual of penicillin in 1940 . thom formally retired in 1942 , although he remained active as a consultant and guest speaker until shortly before his death . memberships and honors thom was the u.s. delegate to the 1905 international dairy congress held in paris , france . he helped establish a graduate education program at the usda . in 1907 , he became a charter member of the dairy association of america , and in 1918 , was appointed president of the bacteriological association of washington . he attended the 1935 international soil congress in oxford , england and was vice president of the 1939 international microbiological congress in new york . he was a member of the national academy of sciences , a charter member of the mycological society of america , and president of the society of american in 1940 and the society of industrial microbiology in 1950 . thom was awarded an honorary doctor of science degree by lake forest college in 1936 . for his work on penicillin , he and his research group received the lasker group award in 1946 , and the usda distinguished service award in 1947 . the same year , he received a gold medal from the spanish national research council for his contributions to microbiology and medicine . described taxa selected publications thom , charles ( 1906 ) " fungi in cheese ripening ; camembert and roquefort " in usda bureau of animal industry bulletin 82 pp. 1 – 39 thom , charles ( 1910 ) " cultural studies of species of penicillium " in usda bureau of animal industry bulletin 118 pp. 1 – 109 thom , charles ; currie , james n. ( 1916 ) " aspergillus niger group " in journal of agricultural research 7 : 1 pp. 1 – 15 thom , charles ; church , margaret b. ( 1918 ) . " aspergillus fumigatus , a. nidulans , a. n. sp. and their allies " . american journal of botany 5 ( 2 ) : 84 – 104 . doi : 10 . 2307 / . thom , charles ; church , margaret b. ( 1921 ) . " aspergillus flavus , a. oryzae and associated species " . american journal of botany 8 ( 2 ) : 103 – 126 . doi : 10 . 2307 / . thom , charles ; hunter , albert clayton ( 1924 ) . " hygienic fundamentals of food handling " 228 pp . thom , charles ; church , margaret b. ( 1926 ) . " the " . 272 pp . thom , charles ( 1930 ) . " the " . 644 pp . thom , charles ( 1954 ) . " the evolution of species concepts in aspergillus and penicillium " . annals of the new york academy of sciences 60 : 24 – 34 . doi : 10 . 1111 / -