Microbiology and Immunology

WORLD OF MICROBIOLOGY AND IMMUNOLOGY Historical Chronology

653

1929 Scottish biochemist Alexander Fleming (1881–1955)

discovers penicillin. He observes that the mold

Penicillium notatuminhibits the growth of some bac-

teria. This is the first anti-bacterial, and it opens a

new era of “wonder drugs” to combat infection and

disease.

1930 Curt Stern, and, independently, Harriet B. Creighton

and Barbara McClintock, demonstrate cytological

evidence of genetic crossing over between eukary-

otic chromosomal strands.

1930 Max Theiler demonstrates the advantages of using

mice as experimental animals for research on animal

viruses. Theiler uses mice in his studies of the yellow

fever virus.

1931 Phoebus A. Levene publishes a book that summa-

rizes his work on the chemical nature of the nucleic

acids. His analyses of nucleic acids seemed to sup-

port the hypothesis known as the tetranucleotide

interpretation, which suggests that the four bases are

present in equal amounts in DNAs from all sources.

Perplexingly, this indicated that DNA is a highly rep-

etitious polymer that is incapable of generating the

diversity that would be an essential characteristic of

the genetic material.

1932 William J. Elford and Christopher H. Andrewes

develop methods of estimating the sizes of viruses by

using a series of membranes as filters. Later studies

prove that the viral sizes obtained by this method

were comparable to those obtained by electron

microscopy.

1934 John Marrack begins a series of studies that leads to

the formation of the hypothesis governing the asso-

ciation between an antigen and the corresponding

antibody.

1935 Wendall Meredith Stanley (1904–1971), American

biochemist, discovers that viruses are partly protein-

based. By purifying and crystallizing viruses, he

enables scientists to identify the precise molecular

structure and propagation modes of several viruses.

Stanley wins the Nobel Prize in Chemistry in 1946.

1936 George P. Berry and Helen M. Dedrick report that

the Shope virus could be “transformed” into

Myxomatosis/Sanarelli virus. This virological

curiosity was variously referred to as “transforma-

tion,” “recombination,” and “multiplicity of reacti-

vation.” Subsequent research suggests that it is the

first example of genetic interaction between animal

viruses, but some scientists warn that the phenome-

non might indicate the danger of reactivation of virus

particles in vaccines and in cancer research.

1936 Theodosius Dobzhansky publishes Genetics and the

Origin of Species,a text eventually considered a

classic in evolutionary genetics.

1937 Hans Adolf Krebs (1900–1981), German biochemist,

describes and names the citric acid cycle.

1938 Emory L. Ellis and Max Delbrück perform studies on

phage replication that mark the beginning of modern

phage work. They introduce the “one-step growth”

experiment, which demonstrates that after bacterio-

phages attack bacteria, replication of the virus occurs

within the bacterial host during a “latent period,”

after which viral progeny are released in a “burst.”

1939 Richard E. Shope reports that the swine influenza

virus survived between epidemics in an intermediate

host. This discovery is an important step in revealing

the role of intermediate hosts in perpetuating specific

diseases.

1939 Ernest Chain and H. W. Florey refine the purification

of penicillin, making possible the mass production of

the antibiotic.

1940 Ernest Chain and E. P. Abraham detail the inactiva-

tion of penicillin by a substance produced by

Escherichia coli. This is the first bacterial compound

known to produce resistance to an antibacterial

agent.

1940 Helmuth Ruska obtains the first electron microscopic

image of a virus.

1941 George W. Beadle and Edward L. Tatum publish

their classic study on biochemical genetics entitled

Genetic Control of Biochemical Reactions in

Neurospora. Beadle and Tatum irradiate red bread

mold Neurosporaand prove that genes produce their

effects by regulating particular enzymes. This work

leads to the one gene–one enzyme theory.

1941 Lipmann describes and identifies the biochemical

and physiological role of high energy phosphates

(e.g., adenosine triphosphate; ATP).

1942 Jules Freund and Katherine McDermott identify

adjuvants (e.g., paraffin oil) that act to boost anti-

body production.

1942 Salvador E. Luria and Max Delbrück demonstrate

statistically that inheritance of genetic characteristics

in bacteria follows the principles of genetic inheri-

tance proposed by Charles Darwin. For their work

the two (along with Alfred Day Hershey) are

awarded the 1969 Nobel Prize in Medicine or

Physiology.

1942 Salvador E. Luria and Thomas F. Anderson publish

the first electron micrographs of bacterial viruses.

The Escherichia colibacteriophage appears to have

a round, or polyhedral head and a thin tail.

1942 Selman Waksman suggests that the word “antibi-

otics” be used to identify antimicrobial compounds

that are made by bacteria.

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