Mengyi Cao

Biography

Education

• Ph.D. Microbiology – University of Wisconsin-Madison, WI, 2017
  • Dissertation: Lrp-dependent virulence modulation in bacterium Xenorhabdus nematophila:from insect pathogenesis to nematode mutualism.
    Advisor: Dr. Heidi Goodrich-Blair
• B.A. Biology – Colorado College, Colorado Springs, CO, 2011

Research Experience

• 2023-26: Staff Associate (Independent Fellow) at Carnegie Institution for Science, Pasadena, CA
  • Establishing Steinernema nematode and Xenorhabdus bacteria as an emerging genetic system for microbial symbiosis and biosensor engineering.
• 2017-23: Postdoctoral Fellow, BBE Division, California Institute of Technology, Pasadena, CA
  • Adaptation of genetics tools in entomopathogenic nematodes of Steinernema spp. and explore their use in nematode-bacteria pathogenic interactions.

Biography

Mengyi received her bachelor’s degree from Colorado College (majoring in Biology with minors in Chemistry and Music) and her Ph.D. from University of Wisconsin-Madison in the Department of Bacteriology. Her PhD thesis focused on genetic regulation of adaptive behaviors of the bacterium Xenorhabdus that switches from an insect pathogen to a mutualistic symbiont of nematodes. Mengyi was trained as a postdoctoral fellow at California Institute of Technology where she developed mutagenesis screen method and CRISPR-Cas9 techniques in entomopathogenic nematode of Steinernema species, enabling stable genetic manipulation in these organisms for the first time. As an independent fellow at Carnegie Institution for Science, she pioneered the use of Steinernema and associated microbes as emerging genetics systems to study how mutualistic and pathogenic bacteria affect nematode physiology, and how these molecular mechanisms inspire the design of bacterial biosensors that detect nematode secreted signals.

At UW-Madison, Mengyi is a Research Scientist leading projects on developing and engineering nematode-microbiome systems from native Wisconsin species to improve their effectiveness in sustainable cranberry pest management. She looks forward to contributing to microbiome-guided solutions for sustainable agriculture and learning about translating fundamental discoveries in host-microbe interactions into practical applications for crop protection and the microbial bioeconomy.

Research Interests

Tool Development: Despite their importance in medicine and agriculture, most parasitic nematodes remain genetically intractable, limiting both fundamental biological research and the development of new genetic tools. I am interested in developing molecular technologies, including CRISPR-Cas9 genome editing, RNA interference, and transfection, in Steinernema nematodes as a scalable genetic platform and extending these approaches to other traditionally non-tractable insect and human parasitic nematodes.

Host-Microbe Interactions: Using the molecular tools I am developing, I employ Steinernema nematodes as an emerging genetic model system to investigate how mutualistic and pathogenic bacteria influence host physiology, including immunity, chemical ecology, and neurobiology. The Steinernema-Xenorhabdus symbiosis is particularly well suited for these studies because its binary association, one host species with one bacterial symbiont species, greatly simplifies host–microbe interactions while preserving the fundamental principles of symbiosis.

Integrated Pest Management: The basic mechanisms of nematode-bacteria symbiosis can inspire engineering designs. I am interested in engineering nematode-microbiome interactions to develop sustainable approaches for agricultural pest management.

Specialization

• CRISPR-Cas9 genome editing in traditionally non-tractable nematodes
• Microbial engineering and synthetic biology
• Molecular mechanisms in mutualistic and parasitic interactions

Publications

Publications

Online Profiles

• Google Scholar
• ORCID: https://orcid.org/0000-0002-3117-3401

Recent preprints under review and in revision

^†denotes corresponding author; **denotes equal contributions.

• Cao, M^†. Environmental factors that impact the development of infective juveniles of entomopathogenic nematode Steinernema hermaphroditum. (2026) doi:10.64898/2026.04.07.717109. In revision: Integrative and Comparative Biology. [link to current preprint]
• Xu, M., Ireri, S. W., Prator, M., Lostroh, C. P. & Cao, M^†. Establishing a genetic part library for tunable double-stranded RNA circuit construction and RNA interference in Caenorhabditis elegans. (2026) doi:10.64898/2026.03.29.715104. In revision: ACS Synthetic Biology [link to current preprint].
• Larsson, E. M., Myers, C. R., Newman, D. K^†. & Cao, M^†. The nematode symbiotic bacterium Xenorhabdus griffiniae can sense and respond to the presence of its host Steinernema hermaphroditum. (2025) doi:10.1101/2025.06.16.660008. Major revision: Applied and Environmental Microbiology. [link to current preprint]
• Ireri, S. W. and Cao, M^†. CRISPR-Cas9 gene editing in the agriculturally beneficial entomopathogenic nematode Steinernema feltiae. BioRxiv 2025.07.18.665633 (2025) doi:10.1101/2025.07.18.665633. [link to current preprint]
• Cao, M^†. CRISPR-Cas9 genome editing in Steinernema entomopathogenic nematodes. bioRxiv 2023.11.24.568619 (2023) doi:10.1101/2023.11.24.568619. Minor revision with no further experiments in Genetics. [link to current preprint]

Peer-reviewed publications

• Chen, V., Marken, J. P., Murray, R. M. & Cao, M^†. Escherichia coli Nissle 1917 Occupies Previously Undocumented Host Niches in the Insect‐Parasitic Nematode Steinernema hermaphroditum. Environ. Microbiol. Rep. 18, (2026). [link to paper]
• Ireri, S. W. & Cao, M^†.  CRISPR-Cas9-based Mutagenesis in the Entomopathogenic Nematode Steinernema hermaphroditum and the Maintenance of Mutant Lines. J. Vis. Exp: JoVE (2025) doi:10.3791/68932. [link to paper]
• Heppert, J. K. Awori, RM. Cao, M. Chen, G. Mcleish, J. Goodrich-Blair, H. Analyses of Xenorhabdus griffiniae genomes reveal two distinct sub-species that display intra-species variation due to prophages. BMC Genom. 25, 1087 (2024). [link to paper]
• Cao, M^†., Schwartz, HT, Tan, C-H and Sternberg, PW^†. The entomopathogenic nematode Steinernema hermaphroditum is a self-fertilizing hermaphrodite and a genetically tractable system for the study of parasitic and mutualistic symbiosis. Genetics 220, (2022). [link to paper]
• Mucci NC, Jones KA, Cao M, Wyatt MR 2nd, Foye S, Kauffman SJ, Richards GR, Taufer M, Chikaraishi Y, Steffan SA, Campagna SR, and Goodrich-Blair H. Apex predator nematodes and meso-predator bacteria consume their basal insect prey through discrete stages of chemical transformations. mSystems. 7(3), e0031222 (2022). [link to paper]
• Cao, M and Goodrich‐Blair, H. Xenorhabdus nematophila bacteria shift from mutualistic to virulent Lrp‐dependent phenotypes within the receptacles of Steinernema carpocapsae insect‐infective stage nematodes. Environ Microbiol 22, 5433–5449 (2020). [link to paper]
• Stilwell, MD**, Cao, M**, Goodrich-Blair, H and Weibel, DB. Studying the symbiotic bacterium Xenorhabdus nematophila in individual, living Steinernema carpocapsae nematodes using microfluidic systems. mSphere 3, e00530-17 (2018). [link to paper]
• Cao, M, Patel, T, Rickman, T, Goodrich-Blair, H, and Hussa, EA. High levels of the Xenorhabdus nematophila transcription factor Lrp promote mutualism with the Steinernema carpocapsae nematode host. Appl Environ Microb 83, e00276-17 (2017). [link to paper]
• Cao, M^†, and Goodrich-Blair, H. Ready or not: Microbial adaptive responses in dynamic symbiosis environments. J Bacteriol 199, e00883-16 (2017). [link to paper]

Micropublications

• Alani, O. S., Cao, M., Goodrich-Blair, H. & Heppert, J. K. Conjugation and transposon mutagenesis of Xenorhabdus griffiniae HGB2511, the bacterial symbiont of the nematode Steinernema hermaphroditum (India). microPublication Biol. 2023, 10.17912/micropub.biology.000772 (2023).
• González-Cavazos, C, Cao, M, Wong, W, Chai, C, Sternberg, PW.Effects of ASD-associated daf-18/PTEN missense variants on Caenorhabditis elegans dauer development. microPublication Biology. 10.17912/micropub.biology.000177 (2019).
• Cao, M., Chai, C, Liu, J, and Sternberg, PW. Application of the red-shifted channel rhodopsin Chrimson for the Caenorhabditis elegans cGAL bipartite system. microPublication Biology 2018, (2018).

Presentations

Presentations

• 2026    Invited speaker at 8th International Conference for Model Hosts, Sissi, Crete, Greece.
• 2026    Selected speaker at SICB annual conference, special symposium: Microbial Symbiosis in the Changing World. Portland, OR.
• 2025    Selected speaker at Cold Spring Harbor Microbiome and Barrier Immunity Conference, ‘Insect-parasitic nematode Steinernema hermaphroditum as an emerging genetic model for nutritional immunity’, Suzhou, China.
• 2025    Invited speaker for Microbiology Seminar Series, George Washington University, Washington DC.
• 2024    Vibrio-Squid Symbiosis Annual Conference, Keynote speaker. Pasadena, CA.
• 2024    Metaorganism Symposium, Keynote speaker: ‘Establish Steinernema nematodesas an emerging genetic model to study microbial symbiosis.’ Kiel, Germany.
• 2024    Seminar Speaker at Max Planck Institutes:
  • Max Planck Institute for Terrestrial Microbiology, Marburg, Germany.
  • Max Planck Institute for Chemical Ecology, Jena, Germany.
• 2024    Symposium for Insect Parasitic Nematodes, Keynote speaker: ‘Steinernema parasitic nematodes in the molecular genetics age: genetics tools help study microbial symbiosis.’ Leuven, Belgium.
• 2022    Invited guest in the podcast Genetics in Your World by Multimedia Subcommittee at the             Genetics Society of America.
• 2022    Selected speaker at Beneficial Microbes Conference, ‘Genetics tools development in Steinernema nematodes to study microbial symbiosis’, Madison, WI.

Awards

Awards

• 2022       Chen Institution of Neurobiology Innovation Grant, Caltech.
• 2021       NSF-Edge joint grant, (produce preliminary data, generate ideas, write, edit, and publish)
• 2021       Center for Environmental Microbial Interactions (CEMI) pilot grant, Caltech
• 2021       Resnick small-scale grant Caltech Resnick Sustainability Institute
• 2019       NIH-NRSA F32 Individual Postdoctoral Fellowship
• 2017       Chair’s Award for Excellence in Research, Department of Bacteriology, UW Madison
• 2016-17  E. Michael & Winona Foster Idea Graduate Fellowship, UW Madison
• 2015       WARF Discovery Challenge Research Award, Wisconsin Alumni Research Foundation
• 2015-16  Louis and Elsa Thomsen Wisconsin Distinguished Graduate Fellowship, UW Madison
• 2011 Venture Grant Program Competitive Funding, Colorado College
• 2007-11  The President’s Scholarship, Colorado College
• 2007-11  International Student Scholarship, Colorado College