With Researcher Spotlights, the Microbial Systems Initiative aims to introduce you to the breadth and diversity of research interests and potential growth opportunities at the University of Illinois Urbana-Champaign campus. We hope that by highlighting both the researchers and their research, we can help you to learn more about and connect with your colleagues to enhance multidisciplinary research and education in microbial sciences here at Illinois.
Sierra S. Raglin, Ph.D.
Postdoctoral Research Fellow
Institute of Genomic Biology
Sierra Raglin is a postdoctoral research fellow in Angela Kent's Microbial Ecology Research Lab. She received her B.S. in Animal Science at Rutgers and completed her Ph.D. in Natural Resources and Environmental Sciences from The University of Illinois in 2023. Her fellowship is within the Infection Genomics for One Health research theme at the Carl R. Woese Institute for Genomic Biology (IGB). Her current research focuses on how humans manipulate soil microbiomes in agricultural systems, including through crop breeding and management practices.
Do you have a personal story to share or path that led to your interest in this area of study?
My journey to microbiome research is a little unconventional and involves numerous different organisms and institutions. My high school (Nyack Senior High School, Nyack, NY) offered a Scientific Research Course through SUNY Albany. The premise of the class was simple: learn about scientific research by exploring anything you find fascinating. It was taught over three years; each year you participated you received four college credits through SUNY Albany. And because it was “curiosity-oriented”, there was a wide diversity of research topics. One student studied the impact of age on daydreaming. Someone identified the impact of 3D images on ocular strain. Another student studied particle physics using the hadron collider at SUNY Stonybrook. My research explored the impact of nitrogen pollution on biological oxygen demand and hypoxia within the Hudson River, which I conducted at Columbia’s Lamont Doherty Earth Observatory. I had always watched a ridiculous amount of Animal Planet growing up, but it wasn’t until this research course that I understood what a scientist actually did. Moreover, it taught me the ecosystem impact of -community structure and function, and the importance of understanding microbial communities for aquatic health.
During my undergraduate degree at Rutgers University-New Brunswick, I worked on the cooperative research and extension farm for three years within the large-animal unit (dairy cattle and thoroughbred horses). It wasn’t until I stepped foot on a farm that I fully understood the complexity within an agricultural nitrogen cycle. Nitrogen is highly mobile, as it undergoes numerous microbially-mediated redox reactions that transform it into leaky, nuisance nitrogen forms, particularly nitrate (NO3-) and nitrous oxide (N2O – yes, laughing gas). Nitrate can cause eutrophication (nutrient enrichment) and leads to the depletion of dissolved oxygen (hypoxia) and degradation of environmental health. Nitrous oxide is a potent greenhouse gas 300 times the greenhouse gas warming potential of CO2. Both nitrogen species are enriched in agricultural systems undergoing fertilization management.
At the same time, I minored in marine science and was introduced to the concept of the marine microbial loop. Side-notehands-on agronomy experience with dairy cattle, and my conceptual understanding of the global importance of marine nitrogen cycling microorganisms, pushed me to pursue a career in nitrogen biogeochemistry and nitrogen ecology. However, you might be asking “why didn’t you go into oceanographic microbial ecology?” My answer is that the best way to solve a problem is to prevent it from occurring. Therefore, understanding of terrestrial nitrogen cycling within industrial agricultural fields seemed like an extremely important setting for managing terrestrial N-loss. And it is estimated that Illinois contributes a significant majority of nitrate draining into the Mississippi River Basin. Hence, I left the banks of the Hudson River for the sea of corn of Illinois to understand the microbial ecology of nitrogen cycling microbiota in industrial corn systems.
How will your work help to improve society or reach people?
I don’t think there’s any version of agricultural sustainability that doesn’t address the nitrogen pollution associated with both inorganic and organic agricultural management and systems. The work in Dr. Kent’s laboratory (in collaboration with Dr. Alonso Favela, Dr. Martin Bohn, and Dr. Fred Below) is groundbreaking because it explores the idea of breeding corn with sustainable microbiome traits that may be leveraged to reduce nitrogen loss. By developing high-yielding corn hybrids which possess biological nitrification inhibition (BNI) – the capacity to inhibit nitrate production in the root environment by suppressing ammonium-oxidation activity – we are poised to use the plant genome to reduce N-loss. This approach can revolutionize crop breeding and help Midwestern ecosystems transition to low-input ecosystems. Moreover, as the rhizosphere microbiome is important for plant growth and fitness, we can identify additional plant-growth-promoting microbiome traits which have underlying host genetic variation to target and exploit.
It is not without its faults, as soil microbiomes are functions of their environment, and nitrogen loss (and the intervention strategies to reduce nitrogen loss) are context dependent. Yet, within Illinois, where millions of acres of corn are cultivated annually, suppressing nitrogen loss through modulating the plant microbiome may be an important intervention strategy because 1) the root system impact on soil microbiomes in Illinois is massive and when scaled-up, producing corn that can suppress nitrate production could have a substantial impact on Illinois-derived nitrate leaching, and 2) cultivar-selection is a relatively straight-forward intervention strategy, as it is a pre-existing behavior conducted by most farmers; agricultural solutions that require systems re-design will need strong support from communities and policy-writers, across scales (county->country). Side note: students interested in agricultural sustainability should seriously consider environmental law and policy; these fields define how, why, and when people interact with the environment (human ecology), and therefore are irrefutable targets for top-down human ecological re-designs required for promoting agroecology and sustainability – scientists can only do so much.
Do you want to tell us about any projects or activities that you are particularly excited about right now?
I'm very excited about a new project I’m working on, in collaboration with Dr. Andrew Margenot (Crop Science), Dr. Angela Kent (NRES), Dr. Pamela Martinez (MCB), and Dr. Marynia Kolak (GGiS). As an African American researcher, I felt the need to apply microbial ecology and soil science to an environmental justice context: marginalized communities within urban ecosystems. While my grandfather is from Danville, and my father is from Chicago, I haven’t felt particularly connected to the maize industrial setting because I grew up in the suburbs of Manhattan and went to undergrad in Central New Jersey (not much corn in the northeast). I personally have experiences with gentrification in Harlem, NY, and Jersey City, NJ, and so I know land use within urban settings is an extremely pervasive problem that adversely impacts environmental and human health. Therefore, when looking for postdoctoral positions, I wanted to prioritize One Health research so that I can transition my research focus into urban ecosystems to explore the multitude of ways urbanization impacts soil and environmental health. The goal of the proposed research is to explore how urban development imprints on soil physiochemistry and the soil microbiome, and to explore potential human and environmental health consequences arising from this. Leveraging a recent soil grid survey for lead contamination conducted by Dr. Andrew Margenot and George Watsons, I plan on using geospatial mapping to develop a geostatistical model of heavy metal distribution throughout Chicago, Illinois, and to use social determinants of health to understand the relationship between human and soil health. Additionally, I plan to identify the impact of metal contamination on soil microbiomes, and reciprocal effect of metal enrichment on microbiome virulence evolution. Every community experiences a varying degree of development, and historically oppressive policies, such as redlining (which graded neighborhoods based on their suitability, and prioritized wealthy White residents for homeowner loans), disproportionately placed industrial projects within Black, Latine, and low-income communities, subjecting them to decades of environmental degradation. Therefore, a core career goal of mine will be to bring microbial ecology to marginalized communities and use it as a tool to investigate structural inequalities unique to Black and Latine Illinois stakeholders, and potentially as a mechanism for improving the collective well-being of marginalized communities.
