Uncovering the role of soil microbes on climate change

Microbes living in the soil play a vital role in global photosynthesis by producing and consuming trace gasses in our atmosphere. Dr. Laura Meredith, assistant professor of ecosystem genomics, genetics, global change, and hydrology and atmospheric sciences, discusses her work to better understand the relationship between microbes, plants, and the atmosphere. She talks about her current field work in Alaska to decipher how this relationship impacts climate change. Dr. Meredith also shares how she thrives as a woman in STEM and supports her fellow female colleagues and students. 

Your research group investigates microbial drivers of soil atmospheric trace gas fluxes. Let’s break that down – what microbes are we talking about, and what are trace gas fluxes?

Microbes are everywhere. We hear more and more about how they're part of our microbiomes that carry out so many important functions in terms of our health and well-being. Likewise, there are a lot of microbes in the environment, and I'm particularly interested in the microbiomes in soil, where there are hundreds of thousands of different types of microbes. In a gram of soil, there's estimated to be a billion microbial cells. I'm interested in who's there. 

I study what microbes do, so a lot of my work is thinking about what kind of tools they have in their little microbial toolkit. Can they eat certain types of carbon, or do they produce greenhouse gases like carbon dioxide or methane? Do they interact with plants and help the plants acquire nutrients and be healthy, or are they involved in some more antagonistic interactions with each other? 

My background is in atmospheric chemistry. I was really interested in the different gases that make up our atmosphere, especially those gases that are found in really minute or trace amounts. Those gases, even though they're found in small amounts, are really important in interacting with radiation and trapping heat or helping produce cloud forming particles that causes air pollution. 

I was really fascinated to find out that some microbes produce a lot of these trace gasses. On the other hand, other microbes have evolved ways to eat them and consume them and remove them from our atmosphere. Those are the types of key characteristics of microbes that I'm interested in understanding.

This summer, you’ll be headed to Alaska to collect samples for your latest project. What is one of the most fascinating places that you've traveled to collect samples?

One of the most interesting places I went to was Siberia with a field course where we were learning about Arctic science. We went to a remote station to witness the evolution of the permafrost with our own eyes. It was incredible being intimately in that type of ecosystem and understanding these massive reservoirs of carbon in the Northern latitudes and how they're changing. It was amazing to be there, to hear the stories of people who had lived there and see things changing to learn more about the way of life of people who live there and think about that in the context of global change solutions.

How do you decide the on sites for your field work?

Overall, we choose the sites on a case-by-case basis. We try to match where our biggest unknowns are and what types of tools we have at our disposal to answer unique questions in different locations.

There are a lot of different field sites that are available to us through the University of Arizona. There's this big experimental agricultural station in Maricopa County. It is such a unique infrastructure with this overhead giant that basically scans and studies the crops from above. It was a really perfect complement for us, as the soil probes we've developed for sampling the soil gases below ground below can be coupled with the information we get from above. 

I've done a lot of research at Biosphere 2, where we have large controlled and enclosed ecosystems, like a tropical rainforest under glass. There, we can run a controlled drought and be ready with all our instrumentation to capture the whole ecosystem response to drought. Again, that's another piece of research infrastructure that's really unique that we can ask specific questions with.

I'm going to Alaska because we recognize that there are some key uncertainties in our understanding of carbon cycling up there. We're looking at the role of soil and soil microbes in our understanding of carbon cycling. It just felt like a natural complement to go up there and design a study where we know that there's this big question that's really important to those systems.

You were also recently awarded the prestigious career award from the National Science Foundation. Over the next five years, you'll receive $750K to further investigate how plants and microbes interact, and you'll also use some of that money to open additional opportunities to students, both within your own research and through a new internship program, that will allow undergraduates to conduct research with industry partners over the summer. Tell us a bit about what this award means to you, and why it was important to you to use part of this funding to create an internship program for a University of Arizona undergrads.

The award means a lot to me because it's five years of support to really embark on a new research vein within my group. I'm really interested in the role of hundreds of different volatile, organic compounds, and we can measure many of them at once with special types of instrumentation. We know that plants produce them, and microbes consume them. It’s a new vein for me that really opens up to even more trace gases. I'm enthusiastic about the work and just having that support to pursue a new line of research.

In terms of the internship, when I was an undergraduate, I was a chemistry major with a concentration on polymer chemistry. My program required getting an internship – their motto was “learn by doing.” I had been studying German, so I was able to get an internship at a big chemical company in Germany. It was a fascinating experience to be in an industry setting and really see what a work environment was like in my field of study. It was formative in some of the ways I think about science, but it also helped me see that I was really interested in academic research and maybe not as much industry at the time. 

It was a great experience for me to understand what was out there and then make a decision on the next step of my career. I'm excited about providing undergraduates that view into what's possible in terms of careers in this industry, or maybe they look at that and make the decision I did that I really did want to keep going to school and pursue this career in academia. I'm really happy to guide students in that hands-on learning,

As a woman in STEM, have you encountered any major difficulties or barriers in your journey to getting you where you are today? If so, what were some of those things or people that were instrumental in helping you chase your dreams?

Earlier on in my studies as an undergraduate and even as a graduate student, I didn't really think about the barriers to being a woman in STEM at all. But then I was a postdoc and faculty member, and I started to see some of the more subtle things that make it difficult for women to succeed.

I'm thankful for all the women who have gone before me and persevered against some of the more obvious types of discrimination, but it can often just be hard to look ahead to full professors and just see that the numbers still aren't equal. It’s hard to be in a room and not see as much equal representation as I did when I was an undergraduate and a graduate student, or that certain people are advancing at different rates than others. 

In some ways, I use that as a motivation. I saw some of my male peers landing jobs before me, and I felt like I'm just as capable. I should stay in academia because I could be successful and capable at all the parts of the job. 

The frustration is definitely still there. It's something that bothers me, but sometimes I just move through it. I think what has been really helpful for me is to always have many types of mentors. Some of them have been women and helped be the kind of a role model that showed me what it looked like to be successful in this field. 

I also have a lot of peer mentorship where I talk with other young, female faculty members who are going through similar challenges. We can give each other advice and just be there for each other. That has been helpful in recognizing that if I do feel like I'm feeling facing a barrier that I'm not alone and finding some different ideas for how to move through it.

In addition to mentorship, is there any other advice that you might give to a young girl who's considering a career as a scientist one day?

Let your interests guide you. You never know where they’re going to take you. 

I've moved all around different fields because there are so many different topics in science that you can study. A lot of times you're really influenced by the context that it's presented to you. I understand that not every class that you're going to take is going to be your favorite class, but keep an open mind, and if you love science and are interested in a career, just let questions grab you. Don’t be afraid if it pulls you into another field that you're uncomfortable with, or you don't know all the language. If it's something that's drawing your attention, just follow it and do your best. 

At some point you start grasping it and making connections that are maybe not as obvious to others. I think there's really an opportunity in just letting yourself get pulled in the directions that influence you and doing your best to learn. In the end, you can do some really interesting science.

That's how I got where I am now with all that interdisciplinary work – I got comfortable in the discomfort. I actually find that to be the most fun part now. 

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