Bacteria are the most abundant organisms in soil, and their activities can have major consequences for plant health. Pathogenic bacteria can devastate the productivity and quality of crops, whereas other species can directly promote plant development. These beneficial bacteria act through diverse mechanisms, including converting nutrients into forms that can be more easily broken down by plants, limiting the spread of pathogens, and helping plants survive our rapidly changing climate. Harnessing the functions of beneficial bacteria has the potential to transform agriculture. A major challenge of the next century will be to determine how they can be employed to help feed the planet.

The Belin lab studies the biology of rhizobia, soil bacteria with the capacity to convert nitrogen gas in the atmosphere into plant-fertilizing ammonia. These rhizobia form intimate symbioses with legumes including soybean, alfalfa, pea, and clover, serving as sustainable alternatives to synthetic nitrogen fertilizers. We use quantitative, cell biological approaches to understand the factors that impact symbiotic productivity in the Bradyrhizobium genus of rhizobia.



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The establishment of legume-rhizobia symbiosis requires incredibly complex developmental processes. Free-living rhizobia in the soil are attracted to signals released by plant roots, and in turn release symbiosis-specific signals that facilitate their colonization and invasion of roots. Once the rhizobia have invaded the inner layers of the root tissue, they are engulfed by plant cells to become intracellular (endo-) symbionts. These endosymbiotic bacteria and the plant cells they infect then proliferate to form a new organ known as the root nodule, consisting of plant cells that each harbor many hundreds of endosymbionts. During proliferation, both partners also shift their metabolic output for mutual benefit: endosymbionts shut down most basal metabolic activity to become powerhouses at nitrogen fixation (the conversion of gaseous nitrogen into ammonia), while legumes allocate much of the sugars derived from photosynthesis to support endosymbiont growth. 

The legume-rhizobia symbiosis is a keystone example of inter-species cooperation, yet we still do not know many of the molecular details of these interactions. We currently have multiple funded projects available for technicians, graduate students, and postdocs to address the following questions:

How do rhizobia organize their membranes, and what are the roles of membrane organization during symbiosis?

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Patterns of membrane fluidity in single Bradyrhizobium cells acquired by super-resolution microscopy.
(Belin et al., in prep)

How do bacteria adapt to the chemical and mechanical stresses presented during the invasion of legume roots?

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Bradyrhizobia (green) colonizing and invading Aeschynomene legume roots (adapted from Bonaldi et al. MPMI 2011)

How are rates of rhizobia and nodule growth controlled - through which partner and

by what mechanisms?

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Aeschynomene nodule growth and localization of Bradyrhizobia (green) in host cells (L) and nodules (R) (adapted from Belin et al. MPMI 2019)




Brittany Belin, PhD, Principal Investigator

Brittany received her B.S. in biochemistry and philosophy from the University of Notre Dame and her Ph.D. in biophysics at the University of California, San Francisco, under the mentorship of Dr. Dyche Mullins. In 2015 she began to study plant-bacteria symbiosis as a post-doc in the laboratory of Dr. Dianne Newman at Caltech. Her laboratory at the Carnegie Institution for Science Department of Embryology, located on the Johns Hopkins campus, opened in August 2020. She is interested in cell biology and symbiosis in all of its forms.

Email: belin at carnegiescience dot edu

Sarah Talamantez-Lyburn, MS: Lab Manager/Technician

Sarah received her B.S degree in Biology from Texas State University. She received her M.S in Biology with a focus in breast cancer and nanotherapeutics in 2018 from Towson University. At the University of Maryland, Baltimore she studied pathways of hyperparathyroidism development using cellular and molecular techniques. She is applying her skills to bacterial-plant symbiosis.

Email: slyburn at carnegiescience dot edu


Evan Lawrence, BS: Technician

Evan received his B.S. in biology and marine science from the College of William & Mary. As an undergraduate, he worked at the Virginia Institute of Marine Science studying how benthic microalgae affect nitrogen loads and the appearance of harmful algal blooms in the York River. He is broadly interested in nutrient cycling and primary producers, and is expanding his knowledge of bacterial genetics and cell biology in the Belin lab.

Email: elawrence at carnegiescience dot edu


Huiqiao Pan, PhD: Postdoctoral Researcher

Huiqiao received her B.S. in Bioengineering from the Hebei University of Science & Technology, China and M.S. in Plant Genetics and Breeding from China Agricultural University. In 2020 she received her Ph.D under Dr. Elizabeth Pierson in Molecular & Environmental Plant Sciences at Texas A&M University. She is interested in deciphering the mechanisms of beneficial symbiosis between plants and microbes at the individual and community level.

Email: hpan at carnegiescience dot edu


Zeke, Lab Mascot



Zelda, Lab Mascot




Interested in joining?

We encourage curious scientists of all stripes to consider joining! Specific openings can be found at the Carnegie Institution for Science job board. Applications for positions can also be sent year-round to Dr. Belin as follows: 


Prospective Graduate Students should apply through the Cell, Molecular, Developmental Biology, and Biophysics (CMDB) graduate program at Johns Hopkins. Already in the program? Please e-mail Dr. Belin to connect!

Prospective Technicians, Staff Researchers, and Postdocs can apply by e-mailing Dr. Belin the following information: cover letter, one page summary of research interests and career goals, CV, reprints of recent publications (if available), and contact information for 3-5 references.


Selected Publications

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Belin, B.J.,Tookmanian, E.M., de Anda, J., Wong, G.C.L., Newman, D.K. (2019) Extended
Hopanoid Loss Reduces Bacterial Motility and Surface Attachment and Leads to Heterogeneity
in Root Nodule Growth Kinetics in a Bradyrhizobium-Aeschynomene Symbiosis.
Mol Plant Microbe Interact. 2019 32 (10), 1415-1428.


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Belin, B.J., Busset, N., Giraud, E., Molinaro, A., Silipo, A., Newman, D.K. (2018) Hopanoid
lipids: from membranes to plant-bacteria interactions.
Nat. Rev. Microbiol. 16(5):304-315.


For a full list of Dr. Belin's publications, see Google Scholar.



Carnegie Institution for Science

Department of Embryology

Maxing Singer Building Rm. 322
3520 San Martin Drive

Baltimore, Maryland 21218

office: (410) 246-3016
lab: (410) 246-3027


Ashley Shim: Undergraduate

Ashley is a student at Johns Hopkins University pursuing a B.S. in Molecular and Cellular Biology. Previously, she worked at University of Southern California studying pressure-driven membranes for water recycling and at JHU under Dr. Lutsenko studying effects of copper in the brain. She hopes to gain a deeper understanding in plant-bacteria symbiosis and important laboratory techniques.

Email: ashim at carnegiescience dot edu

Matt Lubin, BS: Graduate Student

Matt graduated with a B.A. in biology and philosophy from Yeshiva University. After graduating, he joined the Yeshiva-based lab of Dr. Josefa Steinhauer, which focuses on phospholipid remodeling enzymes in Drosophila. Before joining Johns Hopkins as a student in the CMDB program, Matt also spent two years as a lab tech in Memorial Sloan Kettering Cancer Center, studying the relationship between cancer cell metabolism and immune escape. As a scientist-in-training, Matt is generally dedicated to furthering our understanding of how biological phenomenon emerge from molecular mechanisms and interactions. In the Belin lab, he hopes to help elucidate the biophysical and biochemical methods used by bacteria to sense and interact with their environments, especially the plant environment of symbiotic Bradyrhizobia.

Email: mlubin at carnegiescience dot edu