About

Darcy McRose is the Thomas D. and Virginia W. Cabot Career Development Professor in Civil and Environmental Engineering (CEE). The page indicates her role as a faculty member leading the McRose Lab, which involves research activities and mentoring students and postdoctoral fellows. Specific details about her research focus, background, or key contributions are not provided in the page text.

Research topics

• Biology
• Chemistry
• Biochemistry
• Ecology
• Bioinformatics
• Biotechnology
• Environmental chemistry
• Botany
• Inorganic chemistry
• Genetics
• Organic chemistry

Selected publications

• Contrasting Bioavailability of Enterobactin- and Ferrichrome-bound Iron to SAR11 and Other Marine Heterotrophs

  ISME Communications · 2026-04-23

  articleOpen access1st authorCorresponding

  Abstract Microbes frequently navigate the environment with the help of small, excreted metabolites. Iron-binding molecules called siderophores are one such set of secondary metabolites that are commonly used by microbes to access the essential trace element iron. Although many marine microbes produce siderophores, a substantial number, including the highly abundant SAR11 clade of Pelagibacterales, do not and it has remained unclear whether such non-producers can access siderophore-bound iron. Here, we show that iron-limited SAR11 cultures fail to grow in the presence of the hydroxamate siderophore ferrichrome but exhibit robust growth in the presence of the catechol siderophore enterobactin. We confirm that this is linked to iron availability using transcriptomic and 55Fe radio tracer uptake experiments. This phenotype can be explained by the relative lability of enterobactin-bound iron in seawater, a phenomenon that has been previously observed in field studies and which we demonstrate with a simple kinetic model. Further experiments with the marine heterotrophs Phaeobacter inhibens and Vibrio harveyi suggest that enterobactin-Fe is unlikely to support the faster growth rates of these organisms without the use of biochemical uptake mechanisms. Overall, our work provides a model of siderophore use that considers bioavailability conferred through both kinetic and biochemical mechanisms and shows that some catechol-bound Fe may be widely available to small, slow growing marine organisms.

  PublisherOA PDFDOI

• ComplementaryBacterial Functions Enhance Mineralizationof Aromatic Aliphatic Copolyesters within a Marine Microbial Consortium

  Figshare · 2026-02-28

  article

  Plastics are a major environmental concern due to their persistence in natural systems. Biodegradable plastics can mitigate this impact by reducing their residence time in the environment. To constrain the environmental lifetime of these materials, understanding the fundamental principles dictating their biodegradation is crucial. The work presented here probes this complexity by using a 30-member bacterial community enriched from the marine ecosystem to investigate how bacterial consortia mineralize polybutylene sebacate-<i>co</i>-terephthalate (PBSeT), a biodegradable aromatic aliphatic copolyester. Carbon dioxide quantification and isotopic tracing provided evidence of polymer mineralization, while monoculture phenotyping demonstrated no one bacterium could consume all polymer components. Further, coculture incubations revealed complementary functions between community members enhanced mineralization. To explain this enhanced mineralization, dissolved organic carbon and chemical product tracking were performed. Notably, depolymerization of the bulk polymer was dictated by a bacterium unable to consume all polymer components (Pseudomonas pachastrellae), requiring complementary bacteria to achieve enhanced mineralization (Pseudooceanicola nitratireducens or Peribacillus frigoritolerans). This yielded direct experimental evidence of the complementary bacterial transformations that may control polymer mineralization in the environment.

  DOI

• Nitrous oxide produced by denitrifying pseudomonads inhibits the growth of rhizosphere bacteria by inactivating the cobalamin-dependent methionine synthase

  mBio · 2026-03-04

  articleOpen accessSenior author

  ABSTRACT Microbial communities are shaped by complex metabolic interactions, whereby the byproducts of one organism influence the physiology of others. This is exemplified in the microbial nitrogen cycle, where diffusion of free intermediates can drastically reshape the chemical landscape of the environment. One such intermediate, nitrous oxide (N 2 O), is often overlooked as biologically inert. However, emerging evidence suggests this gas may inhibit the activity of some cobalamin-dependent enzymes through a reaction with the cofactor. This raises the possibility that, through such an interaction, N 2 O-producing organisms may shape the microbial communities in which they reside, selecting against organisms that rely on these sensitive cobalamin enzymes. At the plant root, a hotspot of microbial activity, the impact of such interactions may be especially important. To investigate this, we focused on microbial N 2 O production and its effect on methionine biosynthesis, a ubiquitous bacterial process carried out by cobalamin-dependent (MetH) or independent (MetE) methyltransferases. In this study, we show that deleting metE and forcing reliance on MetH sensitizes the denitrifier Pseudomonas aeruginosa to exogenous and self-produced N 2 O. We extend these findings to plant-associated bacteria, where we find that a significant portion of an Arabidopsis thaliana rhizosphere culture collection relies exclusively on cobalamin-dependent methionine synthases and experimentally demonstrate their sensitivity to N 2 O. Finally, we show that the growth of one MetH-reliant rhizosphere isolate is suppressed in co-culture with N 2 O-producing P. aeruginosa . Together, these findings suggest that N 2 O producers can shape microbial ecology at the plant root. IMPORTANCE Microbes that live on plant roots can make important contributions to plant health and often exist in tight-knit communities held together by chemical exchanges. This study investigates an interaction between two such metabolites: the climate-active gas nitrous oxide (N 2 O) and cobalamin. N 2 O can become toxic through a reaction with methionine synthase enzymes that use cobalamin as a cofactor. We asked whether the production of N 2 O by some bacteria curtails the growth of others that rely on these enzymes. Using genetic mutants of a model bacterium and natural isolates from the roots of the plant Arabidopsis thaliana, we showed that N 2 O-producing microbes suppress growth of their sensitive neighbors and that N 2 O sensitivity is common in rhizosphere bacteria. As natural and agricultural soils periodically experience bursts of N 2 O, our results suggest that exposure to this gas may shape the assembly of plant-beneficial microbial communities.

  PublisherDOI

• Associated python code to McRose et al. manuscript submitted to ISME Communications in 2025

  Open MIND · 2026-03-29

  otherOpen access1st authorCorresponding

  This release just differs by a CITATION.cff file

  PublisherDOI

• Complementary Bacterial Functions Enhance Mineralization of Aromatic Aliphatic Copolyesters within a Marine Microbial Consortium

  Environmental Science & Technology · 2026-02-28 · 1 citations

  article

  Plastics are a major environmental concern due to their persistence in natural systems. Biodegradable plastics can mitigate this impact by reducing their residence time in the environment. To constrain the environmental lifetime of these materials, understanding the fundamental principles dictating their biodegradation is crucial. The work presented here probes this complexity by using a 30-member bacterial community enriched from the marine ecosystem to investigate how bacterial consortia mineralize polybutylene sebacate-co-terephthalate (PBSeT), a biodegradable aromatic aliphatic copolyester. Carbon dioxide quantification and isotopic tracing provided evidence of polymer mineralization, while monoculture phenotyping demonstrated no one bacterium could consume all polymer components. Further, coculture incubations revealed complementary functions between community members enhanced mineralization. To explain this enhanced mineralization, dissolved organic carbon and chemical product tracking were performed. Notably, depolymerization of the bulk polymer was dictated by a bacterium unable to consume all polymer components (Pseudomonas pachastrellae), requiring complementary bacteria to achieve enhanced mineralization (Pseudooceanicola nitratireducens or Peribacillus frigoritolerans). This yielded direct experimental evidence of the complementary bacterial transformations that may control polymer mineralization in the environment.

  PublisherDOI

• Gnotobiotic growth and phosphorus limitation of Arabidopsis thaliana and co-occurring microbes on phosphated iron oxides

  BioMetals · 2025-11-27

  articleOpen accessSenior author

  The macronutrient phosphorus is vital for sustaining cellular processes in all life forms. Due to its frequent adsorption on iron minerals, phosphorus bioavailability is low in many soils. While the abiotic adsorption of phosphate on iron minerals has been well studied, the direct effects of this process on bioavailability to plants and microbes has not been thoroughly investigated in a simplified laboratory system. We developed a hydroponic growth system that uses hydrous ferric oxide (HFO) to induce phosphorus limitation and can enable both plant and microbial cultivation as well as gnotobiotic co-culture. We demonstrate that this system can be used for phosphorus-limited growth of the model plant Arabidopsis thaliana as well as two root-associated bacterial isolates (from the genera Rhizobium and Pseudomonas). Elemental analysis of phosphorus and iron concentration in A. thaliana shoots reveals that the addition of increasing amounts of HFO leads to a progressive decrease in phosphorus concentration but does not affect iron quotas. We also report that phosphorus concentrations in both bacterial isolates decrease when cultivated in media supplemented with HFO. We further show that A. thaliana can be co-cultured with a Rhizobium isolate in our phosphorus-limited hydroponic system with bacteria relying on plant photosynthate as their sole carbon source. Our work provides a controlled demonstration of the effects of mineral adsorption on phosphorus bioavailability and a tool for further investigation of how plants and microbes access phosphorus in the environment.

  PublisherOA PDFDOI

• The phospho-ferrozine assay: A tool to study bacterial redox-active metabolites produced at the plant root

  bioRxiv (Cold Spring Harbor Laboratory) · 2024-09-05

  preprintSenior authorCorresponding

  Abstract Soil microbial communities are pivotal to plant health and nutrient acquisition. It is becoming increasingly clear that many interactions, both among and between microbes and plants, are governed by small bioactive molecules or “secondary metabolites” that can aid in communication, competition, and nutrient uptake. Yet, secondary metabolite biogeography – who makes what, where, and why— is in its infancy. Further, secondary metabolite biosynthesis genes are often silent or weakly expressed under standard laboratory conditions, making it incredibly difficult to study these small molecules. To begin to address these dual challenges, we focused on Redox-Active metabolites (RAMs), a specific class of small molecules, and took advantage of recent findings that many RAMs aid in acquiring phosphorus and that their production is frequently stimulated by stress for this macronutrient. We developed a screen for RAM-producing bacteria that leverages phosphorus limitation to stimulate metabolite biosynthesis and uses a colorimetric (ferrozine) iron-reduction assay to identify redox activity. We isolated 557 root-associated bacteria from grasses collected at sites across the United States (Santa Rita Experimental Range (AZ), Konza Prairie Biological Station (KS), and Harvard Forest (MA)) and from commercial tomato plants and screened them for RAM production. We identified 128 soil isolates of at least 19 genera across Proteobacteria, Actinobacteria, Firmicutes, and Bacteroidetes that produced RAMs under phosphorus stress. Our work reveals that the production of RAMs under phosphorus stress is common across diverse soil bacteria and provides an approach to screen for these small molecules rapidly. Importance By secreting secondary metabolites, bacteria at the plant root can defend against diseases and help acquire essential nutrients. However, the genes which synthesize secondary metabolites are typically inactive or are weakly expressed under standard laboratory conditions. This fact makes it difficult to study these small molecules and hinders the discovery of novel small molecules that may play crucial roles in agricultural and biomedical settings. Here, we focus on Redox-Active metabolites (RAMs), a class of secondary metabolites that can help bacteria solubilize phosphorus and are often produced when phosphorus is limited. We developed a screen that rapidly identifies RAM-producing bacteria by utilizing a colorimetric iron-reduction assay in combination with phosphorus limitation to stimulate biosynthesis. The screen reveals that RAM-producing bacteria are far more prevalent in soil than previously appreciated and that this approach can be used to identify RAM producers.

  PublisherDOI

• The phospho-ferrozine assay: a tool to study bacterial redox-active metabolites produced at the plant root

  Applied and Environmental Microbiology · 2024-12-17 · 4 citations

  articleOpen accessSenior author

  Soil microbial communities are pivotal to plant health and nutrient acquisition. It is becoming increasingly clear that many interactions, both among and between microbes and plants, are governed by small bioactive molecules or "secondary metabolites" that can aid in communication, competition, and nutrient uptake. Yet, secondary metabolite biogeography - who makes what, where, and why-is in its infancy. Further, secondary metabolite biosynthesis genes are often silent or weakly expressed under standard laboratory conditions, making it incredibly difficult to study these small molecules. To begin to address these dual challenges, we focused on redox-active metabolites (RAMs), a specific class of small molecules, and took advantage of recent findings that many RAMs aid in acquiring phosphorus and that their production is frequently stimulated by stress for this macronutrient. We developed a screen for RAM-producing bacteria that leverages phosphorus limitation to stimulate metabolite biosynthesis and uses a colorimetric (ferrozine) iron-reduction assay to identify redox activity. We isolated 557 root-associated bacteria from grasses collected at sites across the United States (Santa Rita Experimental Range [AZ], Konza Prairie Biological Station [KS], and Harvard Forest [MA]) and from commercial tomato plants and screened them for RAM production. We identified 128 soil isolates of at least 19 genera across Proteobacteria, Actinobacteria, Firmicutes, and Bacteroidetes that produced RAMs under phosphorus stress. Our work reveals that the production of RAMs under phosphorus stress is common across diverse soil bacteria and provides an approach to screen for these small molecules rapidly.IMPORTANCEBy secreting secondary metabolites, bacteria at the plant root can defend against diseases and help acquire essential nutrients. However, the genes that synthesize secondary metabolites are typically inactive or are weakly expressed under standard laboratory conditions. This fact makes it difficult to study these small molecules and hinders the discovery of novel small molecules that may play crucial roles in agricultural and biomedical settings. Here, we focus on redox-active metabolites (RAMs), a class of secondary metabolites that can help bacteria solubilize phosphorus and are often produced when phosphorus is limited. We developed a screen that rapidly identifies RAM-producing bacteria by utilizing a colorimetric iron-reduction assay in combination with phosphorus limitation to stimulate biosynthesis. The screen reveals that RAM-producing bacteria are far more prevalent in soil than previously appreciated and that this approach can be used to identify RAM producers.

  PublisherDOI

• The chemical ecology of coumarins and phenazines affects iron acquisition by pseudomonads

  Proceedings of the National Academy of Sciences · 2023 · 42 citations

  1st authorCorresponding
  • Biology
  • Botany
  • Chemistry

  , and phenazines, RAMs made by soil-dwelling pseudomonads, to ask whether plant and microbial RAMs might each have distinct functions under different environmental conditions. We show that variations in oxygen and pH lead to predictable differences in the capacity of coumarins vs phenazines to increase the growth of iron-limited pseudomonads and that these effects depend on whether pseudomonads are grown on glucose, succinate, or pyruvate: carbon sources commonly found in root exudates. Our results are explained by the chemical reactivities of these metabolites and the redox state of phenazines as altered by microbial metabolism. This work shows that variations in the chemical microenvironment can profoundly affect secondary metabolite function and suggests plants may tune the utility of microbial secondary metabolites by altering the carbon released in root exudates. Together, these findings suggest that RAM diversity may be less overwhelming when viewed through a chemical ecological lens: Distinct molecules can be expected to be more or less important to certain ecosystem functions, such as iron acquisition, depending on the local chemical microenvironments in which they reside.

  PublisherOA PDFDOI

• Redox-active antibiotics enhance phosphorus bioavailability

  Science · 2021 · 136 citations

  1st authorCorresponding
  • Chemistry
  • Environmental chemistry
  • Biology

  Microbial production of antibiotics is common, but our understanding of their roles in the environment is limited. In this study, we explore long-standing observations that microbes increase the production of redox-active antibiotics under phosphorus limitation. The availability of phosphorus, a nutrient required by all life on Earth and essential for agriculture, can be controlled by adsorption to and release from iron minerals by means of redox cycling. Using phenazine antibiotic production by pseudomonads as a case study, we show that phenazines are regulated by phosphorus, solubilize phosphorus through reductive dissolution of iron oxides in the lab and field, and increase phosphorus-limited microbial growth. Phenazines are just one of many examples of phosphorus-regulated antibiotics. Our work suggests a widespread but previously unappreciated role for redox-active antibiotics in phosphorus acquisition and cycling.

  PublisherOA PDFDOI

Frequent coauthors

• François M. M. Morel

  Princeton University

  7 shared

• Anne M. L. Kraepiel

  Princeton University

  6 shared

• Alexandra Z. Worden

  GEOMAR Helmholtz Centre for Ocean Research Kiel

  6 shared

• Dianne K. Newman

  California Institute of Technology

  4 shared

• Xinning Zhang

  Guangzhou Medical University

  4 shared

• Adrián Reyes‐Prieto

  University of New Brunswick

  4 shared

• John M. Archibald

  Dalhousie University

  4 shared

• Thomas Möck

  University of East Anglia

  3 shared

Labs

• McRose LabPI

Awards & honors

• Packard Fellow for Science and Engineering, 2025
• Maseeh Excellence in Teaching Award, 2025
• Sloan Foundation Research Fellow in Earth System Science, 20…