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The 2007 Virginia Genetically Engineered Machine Team. 2007 iGEM Jamboree. 3 Nov. 2007. http://www.etcgroup.org/en/issues/synthetic_biology.html. The 2007 VGEM Team. University-wide, interdisciplinary science and engineering collaboration among students and faculty.
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The 2007 Virginia Genetically Engineered Machine Team 2007 iGEM Jamboree 3 Nov. 2007 http://www.etcgroup.org/en/issues/synthetic_biology.html
The 2007 VGEM Team University-wide, interdisciplinary science and engineering collaboration among students and faculty Amy, George, Kevin, Ranjan, and Emre
Advisors Ron Bauerle Jason Papin Erik Fernandez Brianne Ray Kay Christopher
Birth of the Team • First UVA iGEM team • Founded, organized and run by us • 16 undergraduates applied • We raised $50,000 and secured lab space • No prior synthetic biology research at UVA • We taught ourselves basic synthetic biology
Project Brainstorming • Bacterial melanogenesis • Ethylene biosensing • Autonomous drug delivery • Cellular photosignalling • Directed angiogenesis http://www.calvin.edu/academic/chemistry/faculty/muyskensmark http://news.bbc.co.uk/cbbcnews/hi/animals/newsid_3233000/3233962.stm Nature. 2000 Jan 20;403(6767):335-8.
Butanol Biosynthesis: Background & Motivation • 90 years ago- Butanol first produced in a lab setting via fermentation • 1950s- Butanol produced petrochemically due to lowered cost • Today- Need for alternate energy source BP DuPont Biofuels. www2.dupont.com/Biofuels/en_US/index.
Butanol Biosynthesis:Background & Motivation • Advantages of Butanol over Ethanol • Less corrosive • Lower latent heat of vaporization • Higher energy density • Less hygroscopic • Fits within current infrastructure • Liquid at atmospheric temperature and pressure • Easily blends with other fuels • Can be used in existing internal combustion engines http://www.bioenergywiki.net/index.php/Biobutanol
Butanol Biosynthesis:Background & Motivation • Butanol is renewable! • However, production is not currently economically feasible • More research is necessary • High cost of substrate • Toxicity to the fermenting organisms
Butanol Biosynthesis: Objectives • Design, model, and modularly construct a metabolic pathway in E. coli that includes the following: • A butanol-producing metabolic pathway • From Clostridium acetobutylicum • A cellulase system (cheap carbon source) • Select enzymes from Saccharophagus degradans • Proteorhodopsin, a light metabolism system (free energy) • Discovered via marine metagenomic analysis • Increase E.coli butanol tolerance via engineering and/or evolution
Proteorhodopsin • Requires retinal • Added to media, not biosynthesized Martinez, A., A. Bradley, J. Waldbauer, R. Summons and E. F. DeLong. 2007. Proteorhodopsin photosystem gene expression enables photophosphorylation in a heterologous host. PNAS.
Results: Butanol Tolerance • Typical Tolerance: 0.8-1.2% (vol/vol) • Unable to get consistent results • At higher butanol concentrations (>1.2%), occasionally cells would survive • These cells were unable to keep butanol tolerance and would be killed if transferred to a new broth
Mathematical Model • Model → experiment → model → etc. • Metabolic pathway → stoichiometric matrix • Flux balance analysis • Fermentation products • Pathway bottlenecks • Knockout simulations
Conclusions • Cellulases and butanol-producing enzymes may be toxic to E. coli • Simple directed evolution of E. coli may not be an effective way of increasing butanol tolerance • Proteorhodopsin is a potential energy-provider for chemical synthesis in E. coli under anaerobic conditions
Ongoing Work • Determine what went wrong with our BioBrick construction and whether or not they are lethal to E. coli • If possible, assemble BioBricks into composite systems • Incorporate better or more membrane-associated solvent efflux pumps to increase tolerance • Incorporate the retinal pathway • Incorporate more diverse cellulases • Complete the central butanol biosynthesis pathway • Design and optimize complete bioprocess
Improvements • Expansion of the team to include more departments at UVA (materials science, electrical engineering, chemistry) • Future funding by corporate sponsorship • Potential intro synthetic biology course to educate new researchers and spread the word. • Better communication with iGEM personnel and other teams (more community-oriented) to solve common problems
Acknowledgements • Our advisors: Erik Fernandez, Jason Papin, Ron Bauerle, Brianne Ray, and Kay Christopher • Our academic sponsors: Office of the VP for Research, School of Engineering, U.Va. Engineering Foundation, School of Medicine, and the departments of Biomedical Engineering, Chemical Engineering, Biology, and Microbiology • Our corporate sponsor: DNA2.0
References • [1] Andrykovitch, G., & Marx, I. (1988). Isolation of a new polysaccharide-digesting bacterium from a salt marsh. Applied and Environmental Microbiology, 54(4), 1061-1062. • [2] Beja, O., Aravind, L., Koonin, E., Suzuki, M., Hadd, A., Nguyen, L., et al. (2000). Bacterial rhodopsin: Evidence for a new type of phototrophy in the sea. Science, 289(5486), 1902-1906. • [3] Borden, J., & Papoutsakis, E. (2007). Dynamics of genomic-library enrichment and identification of solvent tolerance genes for clostridium acetobutylicum. Applied and Environmental Microbiology, 73(9), 3061-3068. • [4] Martinez, A., Bradley, A. S., Waldbauer, J. R., Summons, R. E., & DeLong, E. F. (2007). Proteorhodopsin photosystem gene expression enables photophosphorylation in a heterologous host. Proceedings of the National Academy of Sciences, 104(13), 5590-5595. • [5] Nolling, J., Breton, G., Omelchenko, M., Makarova, K., Zeng, Q., Gibson, R., et al. (2001). Genome sequence and comparative analysis of the solvent-producing bacterium clostridium acetobutylicum. The Journal of Bacteriology, 183(16), 4823-4838. • [6] Taylor, L.,II, Henrissat, B., Coutinho, P., Ekborg, N., Hutcheson, S., & Weiner, R. (2006). Complete cellulase system in the marine bacterium saccharophagus degradans strain 2-40T. The Journal of Bacteriology, 188(11), 3849-3861.
Experiment 1:Testing Alcohol Dehydrogenase aad, aad2 aad, aad2 + alcohol dehydrogenase?
Experiment 2: Butanol biosynthesis from butyric acid atoA atoD
Experiment 3:Cellulose as an Alternate Energy Source cellobiohydrolase, cellobiase Native