Research in the Meredith Lab aims to resolve the microbial imprint on ecosystem processes and atmospheric chemistry. Trace gases are important, but often overlooked, microbial metabolites, and microbial processes can have a leading order impact on atmospheric composition of trace gases. We constrain genetic traits for trace gas metabolism by linking microbial taxa, genes, and trace gas production and consumption kinetics in predictive trait models. Although microbes voraciously cycle trace gases in the complex soil matrix, it is challenging to measure gases at scales that capture variability in time (‘hot moments’) and space (‘hot spots’, gradients). We develop new tools to constrain microbial gas cycling in the subsurface, including novel soil gas probing systems and sensors. Even after microbial processes are understood at the small scale, they must be scaled-up and considered alongside other interacting biotic and abiotic processes in ecosystems and landscapes. We use experimental ecosystems to directly evaluate the emergent outcomes of environmental forcings on ecosystems and collaborate with modelers to implement and improve representation of microbial processes.
Projects:
The future of the atmospheric hydrogen soil sink
With ongoing development of hydrogen (H2) as an alternative energy carrier, there is a renewed interest in advancing basic understanding of H2 in the atmosphere–especially removal mechanisms that counterbalance new H2 emissions associated with H2 energy. At a staggering ~80% of the total sink, microbe-mediated soil H2 uptake is already the dominant buffer against H2 sources. Soil microbiomes respond to elevated H2 by increasing their H2 uptake capacity, suggesting that microbial adaptation may be an overlooked nature-based solution to mitigate adverse atmospheric impacts of new H2 emissions. The overarching goal of this project is to improve understanding of the atmospheric H2 soil sink and its response to elevated H2 from alternative energy systems.
Principal Investigator: Laura Meredith
Co-Investigators: Avelino Arellano (University of Arizona), Elizabeth Lunny, Conner Daube and Rob Roscioli (Aerodyne Research, Inc.)
Funding: NSF AGS Atmospheric Chemistry Award No. 2516265
Related Publications: Buzzard et al., (2022) and Jordaan et al. (2020) soil H2 uptake in arid systems; Meredith et al., (2017), Meredith et al., (2014) and Khdhiri et al., (2017) soil H2 uptake in temperate forests; Meredith et al., (2014) H2 uptake by soil actinomycetes
Press: NEON Research Highlight; UA News
A volatile environment: How volatile mediated plant and microbial interactions extend the rhizosphere and enhance soil carbon storage
Understanding that many VOCs are ubiquitous in both the atmosphere and soil, we propose these compounds represent a significant and oft neglected component of the soil carbon pool. In this project, we are working to quantify the direct and indirect contributions of microbial and plant VOCs in both soil carbon cycling and stabilization, as well as investigate the mechanisms that regulate these processes.
We hypothesize that root VOCs and those that pass through the soil metabolic ‘microbial loop’ directly contribute to soil carbon cycling and stabilization. Moreover, as VOCs can act as signaling molecules that tether soil microbes, plants, and higher-order organisms together, we predict that VOCs can indirectly influence carbon stabilization through these teleconnections. Finally, due to the uniquely large ‘zone of influence’ soil VOC metabolites possess, compared to their non-volatile counterparts, we expect to identify the role of VOC movement between otherwise separated regions of soil that further enhance the conversion of VOCs into stable soil carbon pools.
DOE 2022 Awards Announcement Summary: “[This] work will represent the first quantification of the potential impact of direct, indirect, and teleconnection roles of root VOCs on soil carbon pools. If VOC contributions are significant, this project will directly impact conceptual and numerical models that aim to enhance the understanding of soil carbon cycling and stabilization and contribute to a new frontier in microbial systems science that embraces VOCs as integral components of the suite of organic compounds present in an ecosystem.”
Principal Investigator: Laura Meredith
Co-Investigators: Malak Tfaily (University of Arizona), Elizabeth Lunny and Rob Roscioli (Aerodyne Research, Inc.), Eoin Brodie, Kolby Jardine, and Romy Chakraborty (Lawrence Berkeley National Laboratory)
Funding: Department of Energy Systems Biology–Enabled Microbiome Research to Facilitate Predictions of Interactions and Behavior in the Environment Awards: DE-FOA-0002602.
Publications: Zhang et al., (2026) on VOCs soil carbon transformation and sequestration; Ledford et al., (2025) on volatile traits; Jardine et al., (2025) on plant and microbial C1 relations
Press: A volatile environment – Meredith awarded DOE grant to study VOCs and carbon storage in soil (2022)
Laura Meredith co-created and -led an international research campaign with Christiane Werner (University of Freiburg) and Nemiah Ladd (University of Basel) in the Biosphere 2 Tropical Rainforest biome. The Water, Atmosphere, and Life Dynamics (WALD, meaning ‘forest’ in German) campaign was a 5-month (Sept 2019 – Jan 2020) controlled whole-ecosystem drought and recovery experiment involving >90 participants from 14 institutions and 5 countries, $5M in instrumentation, and >20 media interviews. Our first results were just published in Science (Werner, Meredith, and Ladd, et al., 2021) with an accompanying perspective (Eisenhauer and Weigelt, 2021).
The overarching goal of the experiment was to fully track the forest’s response to drought from molecules to the ecosystem. We accomplished this by measuring multiple ecosystem compartments (atmosphere, leaf, stem, root, soil) online with 133 online gas sampling locations sampled by clusters of gas analyzers for water (H2O) isotopes, carbon dioxide (CO2) isotopes, volatile organic compounds (VOCs), and other trace gases (20 online gas analyzers total) and 290 additional environmental sensors. Moreover, we used the glass and steel structure enclosing the rainforest biome to precisely control the rainfall regime, and also to deliver stable isotope labeling at unprecedented ecosystem scales including whole atmosphere 13C-CO2 pulse labeling to track the speed and fate of C allocation under drought and control conditions and deep water 2H-H2O labeling to trace the role of plant deep water access.
There are many stories emerging from WALD. Our group leads the interpretation drought and rewet responses in volatile organic compound (VOC) and nitrous oxide (N2O, see below) cycling in soil and roots through integration with genomics. We also use measurements of carbonyl sulfide (OCS) to trace stomatal responses to drought.
Leadership: Laura Meredith, Christiane Werner, Nemiah Ladd. Contributions of all team members detailed in the B2 WALD Participation List.
Awards: 2020 University of Arizona Team Award for Excellence for effectiveness, service, and inclusive excellence; 2021 SNRE International Collaboration Award to Meredith; and 2021 College Research Faculty of the Year Award to Meredith.
Funding: Financial support from the Philecology Foundation to Biosphere 2 (Laura Meredith). European Research Council Consolidator Grant #647008 (VOCO2, Christiane Werner). DOE Facilities Integrating Collaborations for User Science (Malak Tfaily, article). SBIR DOE BER Phase II SBIR DE-SC0018459 (Rob Roscioli, Laura Meredith)
Related pubs: Werner, Meredith, and Ladd et al, (2021) Science ecosystem response; Andrews et al., press soil N2O; Crocker et al., (2025) litter VOCs ; Huang et al., (2024) plant C allocation ; Ladd et al. (2023) leaf C allocation ; Hernandez et al. (2023), Nature Microbiology microbial C allocation ; Pugliese et al., (2023) Nature Communications soil VOC fluxes ; Hildebrand et al. (2023) root response; Kühnhammer et al. (2023) deep roots; Byron et al., (2022) Nature chiral VOCs; Kübert et al., (2022) transpiration; Honeker et al. (2022) root response
Press: Science Magazine Perspective (2021); Science Magazine News (2019); #B2WALD on X, more news coverage
Peter Moma and Jan Fudyma sampling soil 
Jess Graham in one of the three soil pits. 
Juliana Gil Loiaza flagging soil sampling sites 
Marissa Clover surveying leaf chambers during VOC cartridge sampling. 
Emily Espelage excavating roots from Piper sp. plants 
Roya AminiTabrizi evaluating meter-long soil cores from around the B2 tropical rainforest 
Soil sampling flagging team Laura Meredith, Marissa Clover, Juliana Gil Loiaza, Jane Fudyma, and Alex Cueva
Microbial drivers of carbonyl sulfide (OCS) soil exchange
OCS is an atmospheric trace gas with potential to constrain estimates of global photosynthesis. Better understanding of OCS soil exchange is needed to use this tracer to dissect biosphere carbon cycling processes.
We build on our findings (Meredith et al., 2018) that fungi dominate microbe-mediated soil uptake of OCS via their carbonic anhydrase (CA) enzymes. We ask whether including fungal CA and OCS reaction rates can improve soil OCS representation in land-atmosphere models. We investigate this question in Boreal and Arctic sites in Alaska, where fungi are key to soil biomass and function and projecting changing components of the carbon cycle is critical.
Team: Laura Meredith (PI), fungal ecologist Jana U’Ren (Co-PI at University of Arizona), atmospheric chemist Roísín Commane (Co-PI at Columbia University), land surface modelers Ian Baker (Co-PI at Colorado State University) and Aleya Kaushik (NOAA). UA
Funding: NSF AGS Atmospheric Chemistry Award No. 1933280
Publications: Franco et al., (2026) Genomic and metagenomic survey of carbonic anhydrase (ISME Communications, Editor’s Choice); Nickerson et al. (2026) Sphagnum microbe-metabolome relationships. See also: Commane et al., 2015; Whelan et al., 2017; Meredith et al., 2018a; Meredith et al., 2018b.
Press: NEON Blog
Unearthing the role of belowground biology in biosphere-atmosphere VOC exchange
The role of soil in biosphere-to-atmosphere volatile organic compound (VOC) exchange is elusive and underestimated. VOCs impact air quality and climate, and are projected to increase in response to global change. To help fill gaps in understanding of the belowground drivers of VOC biosphere-atmosphere exchange, this project will address the following research questions: “Which organisms and metabolic pathways drive belowground cycling of different VOCs?”; “How do soil microbes, roots, and root-microbe interactions affect soil VOC cycling?”; and “What factors control how soil VOC production vs. consumption scale to net soil fluxes?”
The project also includes an integrated education plan designed to bridge gaps in learning, research engagement, and training that currently divide atmospheric chemistry and ecosystem science education at the University of Arizona. To do so, the will develop: 1) a team-based undergraduate research program as a Vertically Integrated Project ; 2) a hands-on course in atmospheric and ecosystem science measurements; and 3) an industry training program.
Leadership: Laura Meredith (PI)
Funding: NSF CAREER AGS Atmospheric Chemistry and BIO Ecosystem Sciences Award No. 2045332
Publications: Touceda-Suárez et al., preprint; Andrews et al., in press; Crocker et al., (2025); Ledford et al., (2025); Ledford et al., (2024); Meredith et al., (2023); Hernandez et al., (2023); Pugliese et al. (2023)
Using subsurface sensors to decode volatile signals in the soils
In an academia-industry collaboration with scientists at QuantAQ, Inc. and Aerodyne Research, Inc., we are developing sensors for volatile organic compounds (VOCs) that can be integrated with soil gas probes. This collaboration leverages multifaceted expertise across the team in sensor design, sensor networks, and machine-learning analytics (QuantAQ); high precision VOC monitoring and quantification (Aerodyne); and biological trace gas cycling in soil (UA). The team’s long-term vision motivating this project is to achieve low-cost, subsurface VOC sensor networks that reveal biological interactions in soil with direct relevance to soil health.
In this project, we explored the prevalence of volatile metabolites in microbial systems. We developed an automated open source R package to predict metabolite volatility (volcalc) (Meredith et al., 2023). We showed that metabolomic approaches underestimate the contribution of volatile compounds to the overall pool of soil organic matter (Honeker et al., 2021) and propose approaches to remedy this oversight with new measurements and analyses that leverage existing multi-omics approaches (Meredith and Tfaily, 2022) including through real-time probes and other sensors as in this project (Dwivedi et al., 2022).
Leadership: Laura Meredith (PI), sensor design and machine learning (Co-PIs David Hagan and Eben Cross, QuantAQ), high sensitivity VOC detection and interpretation (Co-PI Jordan Krechmer, Aerodyne).
Funding: NSF Signals in the Soil in BIO Ecosystem Sciences Award No. 2034192. DOE Office of Science, Office of Biological and Environmental Research (BER), grant nos. DE-SC0023189
Publications: Geffre et al., (2026); biological and chemical degradation of isoprene in soil; Meredith et al. (2023) volcalc automated volatility predictor: Meredith and Tfaily (2022) and Honeker et al., (2021) volatilome as an oft overlooked part of microbial metabolome; Dwivedi et al. (2022) sensors in open science
Developing soil gas probes for monitoring trace gas messengers of microbial activity
In an academia-industry collaboration with scientists at Aerodyne Research, Inc., we develop soil gas probing systems to characterize microbial activity through spatially-resolved belowground trace gas measurements. We focus on detecting nitrogen gases and their stable isotopes including nitrous oxide (N2O), nitric oxide (NO), and nitrogen containing volatile organic compounds (N-VOCs), which represent key intermediates and terminal products of complex nitrogen transformations in soil. To demonstrate the performance of our novel probe materials and sample transfer system, we have deployed this system in two field campaigns including WALD (see above) and at the Maricopa Agricultural Center (MAC).
At MAC, we investigate the belowground genotype-phenotype controls on nitrogen use efficiency of a sorghum bioenergy crop. At the site, a large gantry characterizes plant phenotypes from overhead, which are the observable plant characteristics that arise from interactions between the plant (genotype) and its environment. We hypothesize that distinct sorghum genotypes will also differ in their below-ground phenotypes in ways that differentially influence N cycling. We use soil gas probes beneath the sorghum plants and root/rhizosphere analyses to dissect the plant-microbe interactions influencing nitrogen cycling.
Leadership: Joseph R. Roscioli (PI), Joanne Shorter (Co-PI), and Jordan Krechmer (Co-PI) at Aerodyne Research, Inc. and Laura Meredith (Co-PI) at University of Arizona.
Funding: DOE BER Phase I & II SBIR DE-SC0018459
Publications: Andrews et al. in press; Geffre et al., (2026); Roscioli and Meredith et al., (2021); Gil-Loaiza et al, (2021)
Green infrastructure impacts on soil health and ecosystem function
Urban Rainwater Harvesting. Impacts on Soil Microbial Communities and Function Including Gas Fluxes. Urban soils are often degraded compared to their natural counterparts, and in this study we ask how microbial community composition and function are altered upon green infrastructure (GI) installation. The GI systems we study passively and actively utilize rainwater captured from roof run-off during the monsoon and winter storms, and grey water systems are fed annually by laundry water. As water is the limiting factor in arid environments, we anticipate that these treatments will dramatically re-shape microbial communities and lead to altered biogeochemical cycling.
Leadership: Laura Meredith (PI)
Funding: UA Provost Investment Fund, RII Faculty Seed Grant, RII Accelerate for Success
Related pubs: Buzzard et al., (2022) Soil H2 uptake in GI systems; Buzzard et al., (2021) GI impact on soil health