Food Protection Trends - July/August 2024 - 310

Gail Dack: Food Microbiology Pioneer
GENERAL INTEREST PAPER
Charles J. Czuprynski* and Wendy Bedale
Food Research Institute, University of Wisconsin-Madison, Madison, WI 53706, USA
SUMMARY
Gail Monroe Dack, PhD, MD, was a microbiologist who
profoundly affected our understanding and management
of foodborne disease. Yet we suspect many modern food
microbiologists know little about him or his work. His career
spanned the 1920s to 1970s, an era in which the insights,
accomplishments, and tools available to microbiologists
underwent amazing transitions. One can only imagine the
wonder Dack would have today at our ability to analyze the
molecular sequence of microbes, sometimes isolated from
distant geographic locations, and link them to a single source
in an ongoing outbreak.
1. EARLY YEARS
Born in Belvidere, IL, on March 4, 1901, Gail Dack
attended Elgin High School. Following graduation in
1918, Dack attended the University of Illinois at Urbana-
Champaign, receiving his scientiae baccalaureus (equivalent
to a modern bachelor of science degree) in 1922. Dack
demonstrated an interest in biomedical research even as an
undergraduate and was coauthor on a paper published in
1922 (54) that described the isolation of toxin-producing
strains of Clostridium botulinum type B from the feces of two
healthy people.
2. UNIVERSITY OF CHICAGO, 1922-1929
Dack then moved to the University of Chicago as a
graduate research assistant in the Department of Hygiene
and Bacteriology, where he was mentored by Professor E. O.
Jordan (Fig. 1), chairman of the department and one of the
microbiology pioneers in the United States. Jordan's book
Food Poisoning (later edited by Dack) was the seminal text on
food microbiology and foodborne disease at that time, and
Jordan was the editor of and later coeditor with W. Burrows
of Microbiology, a widely used text for decades.
Dack quickly exhibited exceptional productivity and
intellectual flexibility that allowed him to address an array of
microbiological research studies. He used the relatively new
discipline of immunology to produce and use antibodies as
tools to delineate the contributions of C. botulinum toxins to
disease. His thesis research demonstrated that outgrowth of
vegetative cells was required for toxin production (46) and
that C. botulinum spores could remain viable but dormant for
long periods in vivo (47). Identifying botulinum toxin then,
as now, relied on the mouse bioassay. Dack explored some
limitations of the bioassay and the rudimentary equipment
used to produce the anaerobic environment needed for
growth of C. botulinum (6).
Dack was awarded a PhD on June 14, 1927, and named
an instructor in hygiene and bacteriology at the University
of Chicago in 1926 and subsequently an assistant professor
in 1929. His research publications during his early years at
the University of Chicago focused largely on C. botulinum
and other Clostridium species and their exotoxins. This
topic was central throughout Dack's career and became an
important focus of the Food Research Institute (FRI) that
he later founded. Research on C. botulinum and its toxins
remains a core strength of the institute to this day. Dack's
research described the relationships of C. botulinum growth,
proteolysis, and toxin production (19, 27) and defined the
role of oxygen in inhibiting the growth of C. botulinum (13).
Dack was involved in studies of other pathogenic bacteria.
These included verifying that salmonellosis was an infection,
not a toxicosis, after the experimental inoculation of live, but
not heat-killed, cells of Salmonella species in rhesus monkeys
(16, 25). In the 1920s, experimental inoculation of human
volunteers with viable pathogens was not uncommon. Dack
was involved in several such studies, including experimental
inoculation of human volunteers with culture filtrates of
Salmonella Paratyphi (16) or a cocktail of Salmonella strains
(17). The latter failed to cause significant clinical symptoms,
which might have been met with disappointment by the scientists
conducting the study but undoubtedly was welcomed
by the volunteers. Concern about human subject research
was limited in that era, and oversight by institutional review
boards, with which contemporary biomedical scientists are
familiar, did not exist.
3. UNIVERSITY OF CHICAGO, 1930-1939
In 1933, Dack completed the clinical and other
requirements for a doctor of medicine degree from the
University of Chicago while fulfilling his research and
teaching responsibilities as an assistant professor. Four
years later, he earned a promotion to associate professor in
what was then called the Department of Microbiology and
Parasitology. During this decade, he conducted seminal work
on the role of Staphylococcus aureus enterotoxin in foodborne
disease and a series of investigations into the putative role of
the anaerobe Bacterium necrophorum in ulcerative colitis.
It is difficult to overstate the impact of the work by
Dack and his colleagues on foodborne disease caused by
S. aureus. In a groundbreaking report, he demonstrated
310 Food Protection Trends July/August
*Author for correspondence: Phone: +1 608.263.6826; Email: charles.czuprynski@wisc.edu
https://www.foodprotection.org/files/food-protection-trends/jul-aug-24-Czuprynski.pdf
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