Sean Leonard

Contact information

Lawrence Livermore National Laboratory
7000 East Avenue, L-452
Livermore, CA 94550



Ph.D. in Cellular and Molecular Biology, University of Texas, 2020.
M.S. in Biotechnology, University of Texas San Antonio, 2014
B.S. in Molecular Biology, Loyola University, 2006. 


I'm a synthetic biologist fascinated by microbes, evolution, and symbiosis, so I enjoy using evolutionary thinking to solve problems in microbial synthetic biology. I previously developed and applied new tools for genetic engineering of non-model bacteria from the gut microbiome of honey bees, and I showed these engineered microbes can directly manipulate gene expression and their host's behavior here. I believe microbiome engineering, whether in bees or in other environments, can profoundly benefit society but must be used responsibly. 

How can we ensure genetically engineered microbes perform reliably and robustly but without disrupting natural environments?  At LLNL I'm working to understand how diverse microbes adapt to the loss of essential genes, and how these engineered auxotrophies can then be used to confine engineered microbes. I am also designing and testing pairs of genes with overlapped coding regions. These designs can prolong synthetic gene function and restrict horizontal gene transfer of engineered elements. I routinely combine laboratory experiments with computational analyses including microbial genome assembly and annotation, RNA sequencing, and transposon sequencing.  

My work is currently supported by the Biocontainment SFA.


Recent publications

Google Scholar

1. K. M. Elston, S. P. Leonard, P. Geng, S. B. Bialik, E. Robinson, J. E. Barrick, Engineering insects from the endosymbiont out. Trends Microbiol. (2021), doi:10.1016/j.tim.2021.05.004.

2. J. E. Powell, J. Elijah Powell, Z. Carver, S. P. Leonard, N. A. Moran, Field-Realistic Tylosin Exposure Impacts Honey Bee Microbiota and Pathogen Susceptibility, Which Is Ameliorated by Native Gut Probiotics. Microbiology Spectrum(2021), , doi:10.1128/spectrum.00103-21.

3. R. D. Horak, S. P. Leonard, N. A. Moran, Symbionts shape host innate immunity in honeybees. Proc. Biol. Sci. 287, 20201184 (2020).

4. G. A. Suárez, K. R. Dugan, B. A. Renda, S. P. Leonard, L. S. Gangavarapu, J. E. Barrick, Rapid and assured genetic engineering methods applied to Acinetobacter baylyi ADP1 genome streamlining. Nucleic Acids Res. 48, 4585–4600 (2020).

5. S. P. Leonard, J. E. Powell, J. Perutka, P. Geng, L. C. Heckmann, R. D. Horak, B. W. Davies, A. D. Ellington, J. E. Barrick, N. A. Moran, Engineered symbionts activate honey bee immunity and limit pathogens. Science367, 573–576 (2020).

6. B. Zhang, S. P. Leonard, Y. Li, N. A. Moran, Obligate bacterial endosymbionts limit thermal tolerance of insect host species. Proc. Natl. Acad. Sci. U. S. A. 116, 24712–24718 (2019). 

7. P. Geng, S. P. Leonard, D. M. Mishler, J. E. Barrick, Synthetic Genome Defenses against Selfish DNA Elements Stabilize Engineered Bacteria against Evolutionary Failure. ACS Synth. Biol. 8, 521–531 (2019).