In Memoriam: Lars G. Ljungdahl

University of Georgia Professor Emeritus Lars G. Ljungdahl passed away in July 2023 at the age of 96. A pioneer in the field of anaerobic metabolism, Ljungdahl made remarkable discoveries leading to a set of biochemical reactions now known as the Wood-Ljungdahl pathway, and about supramolecular cellulosome complexes that efficiently digest cellulose.

Ljungdahl joined the faculty of the Franklin College of Arts and Sciences department of biochemistry in 1967 as an assistant professor from Case Western Reserve University, a time when UGA was undergoing a major expansion. With support of facilities in fermentation, amino acid analyses and sequencing, mass spectroscopy, electron microscopy, NMR, EPR, X-ray crystallography, antibody production, and bioinformatics, Ljungdahl’s lab made major discoveries in areas related to understanding the origins of life, dealing with climate change, and sustainability.

“Professor Ljungdahl will be remembered as the quintessential example of the value of curiosity-driven research done well because that is how rigorous foundations are laid for future studies of utmost important for mankind,” said Chris West, professor and head of the department of biochemistry and molecular biology. “He was a kind and modest scientific giant deeply interested in the biochemical origins of life and modern-day sustainability. He brought notoriety to UGA and was a tireless advocate for the importance of our research programs.“

In service of that curiosity, Ljungdahl discovered a mechanism by which bacteria capture carbon dioxide to convert into a simple organic compound and building block of life called acetate. Known as the Wood-Ljungdahl pathway, it plays a significant role in the fixation of carbon dioxide on Earth.

His studies of a new bacterium at the center of this pathway resulted in its naming in his honor: Clostridium ljungdahlii.  Along the way, he also discovered that tungsten, the material of light bulb filaments, is a biologically active metal. “He was truly ahead of his time, as we are now in an age when scientists are vigorously exploring the use of microorganisms to abate the build-up of earth warming CO2 in our atmosphere,” West said.

Ljungdahl’s second major discovery involved the degradation of plant lignocellulose, a process that began when he was in his 20’s at the Stockholm Brewery Company, with the idea to obtain an enzyme that processes complex carbohydrates of barley to form fermentable sugars. He decided to investigate some newly discovered anaerobic microorganisms for their ability to ferment cellulose and other easily available substrates that could be converted to feedstock chemicals and biofuels. His lab’s work greatly expanded the knowledge of cellulose degrading machines in bacteria and fungi, now currently popular areas of investigation ­for the conversion of plant materials into sugars that can be fermented to ethanol, an alternative to gasoline.

His research was continuously supported by the National Institutes of Health (NIH) for almost 30 years, and by the Department of Energy. He co-published with 17 colleagues from many departments including Microbiology, Genetics, and Chemistry, illustrating his deep involvement with the collaborative environment of UGA. 

With Norman Giles and Sidney Kushner from the department of genetics, and Milton Cormier and Leon Dure from biochemistry, Ljungdahl was instrumental in working with then UGA President Fred Davidson on the designs and construction of the Davison Life Sciences Building, which has housed the two departments since 1991.

Ljungdahl was influential in the early days of organizing the Georgia Research Alliance (GRA) in 1990 that included six research universities, the state of Georgia, and several major industries. His service with the GRA promoted biosciences and helped set up the BioCrystallography X-ray facility led by B.-C. Wang and provide the investment to equip a beamline at a leading synchrotron facility at Argonne National Labs and the organization of the SouthEast Regional Collaborative Access Team (SER‐CAT).

He was an editor for 10 years for the American Society of Microbiology journal Applied and Environmental Microbiology, and has been honored with two symposia in his name: “The Arts of Anaerobes” and “Incredible Anaerobes: From Physiology to Genomics to Fuel.” He was elected to the Royal Swedish Academy of Engineering Sciences.

Ljungdahl retired from UGA in 2006 as Georgia Power Distinguished Professor in Biotechnology.

To celebrate his accomplishments and his deep ties to the University of Georgia, his late wife Despy Karlas established, in 2007, an endowment that funds the annual Lars G. Ljungdahl Lectureship in the Department of Biochemistry & Molecular Biology and will continue to honor his legacy in perpetuity. The Lars G. Ljungdahl Professorship, originally named the “Georgia Research Alliance Lars G. Ljungdahl Distinguished Investigator,” was created by the Franklin College in his honor in 2005. The position is currently held by Robert J. Schmitz.