Tony Palumbo’s early research as a microbiologist focused on the ocean, but it was moving to landlocked Tennessee to work at Oak Ridge National Laboratory that created a wave of new opportunities through the rest of his career. Palumbo started at ORNL as a postdoctoral associate working on a stream acidification project. Over his 30 years at the laboratory, he led many different groups focused on microbiology, remediation activities, and plant science and served as the director of the Biosciences Division for nearly 10 years. In his latest role, Palumbo launched a new focus area called Bio-Scales that brings together a suite of capabilities to speed the identification of gene functions.
Palumbo’s collaborative approach and science leadership have been a boon to the laboratory and the many scientists he has worked with. Here he shares some reflections on his time at ORNL on the eve of his retirement.
Could you share a bit about how your research evolved over time?
I started out doing marine science before I came to ORNL, so I always say my career goes from oceans to less and less water. Throughout, I focused on microbial ecology in different types of environments. I've studied oceans, streams, lakes, estuaries, subsurface mud, and deep aquifers. But it's always been microbial ecology, and the techniques have changed tremendously during my career.
One of the most interesting things is when I started in marine science, people used to do microbial ecology by using plate counts, which means growing microbes on a petri dish. You’d find maybe 10 bacteria per milliliter. My professor John Hobby started using fluorescent microscopy to look at bacteria in the ocean. And there's actually more like a million per milliliter. We couldn’t identify them or get many to grow in the lab, but at least we knew they were there.
Now, with DNA-based techniques, you can identify microbes without growing them. This is key, because growing microbes in the lab is still challenging. One of the biggest changes in my career has really been the techniques that enable us to understand these microbial systems better.
What were some of your biggest accomplishments while at ORNL?
When I came to ORNL, I was the sole microbiologist. Gradually, we hired more people. I had a hand for about 20 years in hiring everybody who came in as a microbiologist. Now microbiology is a real strength of the laboratory with basically half of the Biosciences Division devoted to it. I'm pleased to have helped make that happen.
Another thing I'm proud of is getting the mercury science focus area (SFA) project off the ground. That was one of the original SFAs. I had just gotten a project funded to look at microbial controls of mercury methylation, investigating the genes involved. There were three or four other projects funded. DOE asked us to combine what we were doing and make it an integrated project.
We went through a process to discuss what that SFA project would be. There were two contending ideas of doing something on uranium or mercury. We ended up going with mercury, and that was based in part on my funded project. Over a number of years, the SFA led to the discovery of the genes that control mercury methylation. People had been trying to solve the problem of how mercury is methylated in the environment for about 40 years. We looked at the problem and saw there were a lot of new techniques that could be applied, and eventually, we achieved the goal.
Early in my career, DOE was concerned about degradation of chlorinated solvents, which are widely used for industrial purposes like dry cleaning and degreasing machine parts. They are also a byproduct of creating nuclear fuels. Everybody was looking for bacteria that could degrade chlorinated solvents, and we isolated the first bacteria that was shown to be capable of doing so.
What did you enjoy most about working at a national laboratory?
It's really about the collaborative atmosphere and the people. When I came to ORNL, there were all these researchers who had been working here for five, 10, 20 years who really knew what they were doing. They were all very cooperative in helping a new postdoc and getting me going. I think that is one of the real benefits of ORNL. That kind of atmosphere. Where if you need geophysics help or you need geochemistry or imaging or proteomics, there's likely an expert down the hall. I also enjoyed the feeling of accomplishment from making discoveries. You can fulfill your curiosity in a way that benefits society.
What are you excited about as you envision the future of biological research at ORNL?
We know so much more now about the microbes that are present in different environments, and because we can sequence them, we have clues to what the microbes are doing. The really exciting research going on at ORNL now is our concept of Bio-Scales and understanding how DNA contributes to certain phenotypes or characteristics. Currently, most of the DNA in bacteria is basically proteins of unknown function. We know they're there. If they're there, they're probably important, but we don't know what 70 to 90% of those genes are doing. There are a lot of emerging techniques that ORNL is working on and adapting that should allow us to get at those questions much more rapidly. I think that's really an exciting direction for the laboratory—to accelerate the identification of gene functions.
The ability to tailor microorganisms to the environment by understanding what the different genes are doing is a big advance. In bioenergy, for instance, having a better grasp of the genes that influence how bacteria grow in a bioreactor could help us control the buildup of acids that are toxic to the bacteria and make production of biofuels cheaper and faster. For plants, the opportunities are similar. How can we alter the plant so we're achieving maybe more than one goal, such as producing above ground carbon for biofuels and maximizing below ground carbon sequestration? One of the focuses will be on trying to do that without adding nitrogen. Nitrogen run- off into rivers can cause ocean dead zones, or nitrogen can be converted to nitrous oxide by soil bacteria and affect the atmosphere as greenhouse gas. So, again, if we improve understanding of gene function, we'll end up with better control of those types of situations.
Because of COVID-19 and some other factors, it looks like there may be more opportunity for ORNL to pursue human health research. That’s an area where we've developed a lot of expertise that's applicable. I’m excited about seeing the laboratory apply artificial intelligence, supercomputing resources, and neutron science to questions in human biology.
What advice would you offer to scientists just beginning their careers?
Be collaborative. It’s very hard to make a big impact if you don’t take advantage of the very collaborative atmosphere at ORNL. Having great collaborators is necessary now more than ever due to the complexity of the science and the instrumentation necessary to make discoveries.
