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Professor Emeritus Arnold Demain, a pioneer in the development of antibiotics, dies at 92

An eminent microbiologist, Demain conducted groundbreaking antibiotics research and mentored hundreds of young scientists.
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Professor Emeritus Arnold "Arny" Demain
Professor Emeritus Arnold "Arny" Demain
Photo: Steven Brener

Arnold Lester Demain, professor emeritus of biology, passed away on Apr. 3 at the age of 92 from complications due to Covid-19. He was just shy of celebrating his 93rd birthday.

Demain advanced the field of fermentation biology, and made major contributions to the study of antibiotics like penicillin, cephalosporin, and beta-lactam. Over the course of his 60-year career, he made a name for himself as one of the world’s leading industrial microbiologists, and mentored hundreds of budding scientists around the world.

“Arny was a prolific industrial biologist, as well as a colleague and friend,” says Alan Grossman, head of the Department of Biology and the Praecis Professor of Biology. “His work on antibiotic fermentations spurred a new wave. He was kind and supportive to all, and a dedicated mentor to many students and postdocs.”

Demain was born on April 26, 1927 in Brooklyn, New York, and grew up during the Great Depression. He graduated from high school at the age of 16, and attended Michigan State College (now Michigan State University). At 17, he put his education on pause to join the U.S. Navy and fight in World War II. After the war ended, he returned to Michigan State and resumed his studies, earning his bachelor’s degree in 1949 and his master’s in microbiology in 1950, with a focus on food fermentation — specifically, how pickles spoil. During this time, Demain met his wife Joanna (Kaye) Demain, and they were married on August 2, 1952.

Demain began his PhD in food science at the University of California at Berkeley, but relocated to Davis when that campus opened. Under the guidance of his research advisor and prominent yeast scholar, Herman Jan Phaff, Demain studied the degradation of pectic acid by an extracellular enzyme in the yeast Klyveromyces fragilis, publishing four papers, including one in Nature. Demain and Phaff were also among the first researchers to perform affinity chromatography, which later became a standard biochemical procedure.

After earning his PhD in 1954, Demain was recruited by Merck Sharp & Dohme Research Laboratories, first to research penicillin biosynthesis and later to study cephalosporin C. In 1965, he established Merck’s Fermentation Microbiology Department.

After 16 years at Merck, Demain joined MIT’s former Department of Nutrition and Food Science, and in 1988 he joined the Department of Biology. When he first arrived, no one at MIT was conducting research on antibiotics. He was eager to continue investigating penicillins and cephalosporins, and his hard work culminated in the breakthrough discovery of a key enzyme in cephalosporin biosynthesis: deacetoxycephalosporin C synthase.

Rich Losick PhD ’69 was finishing his graduate work at MIT when Demain arrived on campus. Demain later interacted with Losick’s wife Janice Pero and former postdoc John Perkins because all three shared an interest in vitamin B2 research. “I was drawn to Arny due to his warm and engaging personality and my interest in microbiology,” Losick recalls. “He pioneered industrial production of vitamins, antibiotics, and fine chemicals, and was revered for his many contributions to industrial microbiology. He was a big-hearted human being, an excellent and productive scientist, and a dedicated teacher. He will be greatly missed.”

While at MIT, Demain also helped catalyze the biotech industry by serving as the founding consultant for the biotech company, Cetus Corporation. By the mid-1990s, he’d spearheaded a series of NASA-sponsored experiments to probe the effects of simulated microgravity on secondary metabolism. Toward the end of his 32 years at MIT, he began examining Clostridium tetani and Clostridium difficile bacteria in hopes of devising tetanus and antibiotic-associated diarrhea vaccines. He ultimately authored more than 500 publications and 21 U.S. patents. 

“Arny had a keen mind and a gentle disposition that put you at ease,” says Gerald Fink, professor in the Department of Biology and founding member and former director of the Whitehead Institute. When Fink started at MIT, Demain was the first to greet him. “He dropped into my office in Building 56 and he said, ‘You are going to like it here,’” Fink recalls.

“Arny was a wonderful colleague,” adds Robert Sauer, the Salvador E. Luria Professor of Biology. “He was always upbeat and happy to talk about science or anything else on your mind.”

Professor of Biology Anthony Sinskey shared an office with Demain, and remembers him as a pioneer who applied genetics and biochemistry to improve antibiotic production processes. He says Demain was instrumental in forming important interdisciplinary programs at MIT — including using anaerobic microorganisms to convert cellulose to fuels, as well as strategies for cell free synthesis of antibiotics and other projects.

“I learned a tremendous amount from our interactions,” Sinskey says. “He taught industrial microbiology and fermentation technology to hundreds of students both at MIT and from industry.”

While Demain was at MIT, an informal group of students formed called Arny’s Army and Friends. Since his “early” retirement from MIT at age 75, Demain’s students have held the Arny’s Army and Friends Symposia in his honor every three years.

Later, Demain would recall that he “was very lucky ... to have had a fantastic group of bright and hardworking visiting scientists, postdoctoral associates, graduate students, undergraduate students and high school students. ... Success at MIT would not have been possible without them.”

Abraham L. “Linc” Sonenshein first crossed paths with Demain as a graduate student at MIT. From the beginning, Sonenshein could tell Demain was “a very important scientist to interact with,” because of the way he applied his knowledge of microbiology to prevent and treat infections. “I was amazed that he continued to contribute to science publication and training for decades after officially retiring as a full-time faculty member,” Sonenshein says. “The number of scientists he educated and trained is phenomenal.”

In 2000, Demain moved to Madison, New Jersey, and joined the Research Institute for Scientists Emeriti (RISE) at Drew University. He continued to conduct research and mentor students until May 2019, when he fully retired at the age of 92. That same year, Drew University established an endowed scholarship in his name.

Over the course of his career, Demain earned numerous awards, including one from the king of Spain and another from the emperor of Japan. He was also a member of the National Academy of Sciences, president of the Society for Industrial Microbiology, and on the Board of Governors for the American Academy of Microbiology.

He is survived by his wife of 68 years, Joanna (Jody) Demain; his daughter, Pamela Demain; his son, Jeffrey Demain; his daughter-in-law, Lauren Brener; his grandchildren; and his great-grandchildren. A memorial service for family, friends, colleagues, and former students will be held when it is safe to do so. Donations in his memory can be made to the Alzheimer's Foundation of America.

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