1、Synthetic Biology in the Quest for Renewable Energy,Jay KeaslingBerkeley Center for Synthetic Biology University of California & Lawrence Berkeley National Laboratory Berkeley, CA 94720,The need for renewable energy,US Energy demands to grow Reduction of US CO2 emissions Production of clean, cheap e
2、nergy,Biomass: a source for renewable energy,About half of the carbonaceous compounds in terrestrial biomass are cellulose. The net primary production of biomass is estimated to be 60 Gt/yr of carbon in terrestrial and 53 Gt/yr in marine ecosystems. Almost all of the biomass produced is mineralized
3、again by enzymes which are provided by microorganisms. Polysaccharide hydrolysis is one of the most important enzymatic processes on earth.,Lignocellulose,Nearly universal component of biomass Consists of three types of polymers: Cellulose Hemicellulose Lignin All three are degraded by bacteria and
4、fungi,Cellulose,Cellulose is a chemically homogeneous linear polymer of up to 10,000 D-glucose molecules, which are connected by -1,4-bonds.,Taken from http:/www.lsbu.ac.uk/water/hycel.html,3-D Cellulose Structure,Hemicellulose,Hemicellulose is a polysaccharide composed of a variety of sugars includ
5、ing xylose, arabinose, mannose. Hemicellulose that is primarily xylose or arabinose are referred to as xyloglucans or arabinoglucans, respectively. Hemicellulose molecules are often branched. Hemicellulose molecules are very hydrophilic. They become highly hydrated and form gels.,Hemicellulose struc
6、ture,Cellulose to ethanol,Taken from Demain et al. 2005. Microbiol. Mol. Biol. Rev. 69:124-154.,Cellulose,Hemicellulose,Cellobiose,Xylose Xylobiose,C. thermocellum,C. thermosaccharolyticum,Ethanol,Lactate,Acetate,Cellulase,Hemicellulase,60C,Cellulosome structure,Cellulosome structure,Stable anchors
7、cellulosome to cell surface,Cellulosome structure,More active against crystalline than amorphous cellulose Form lengthened corridors between cell & substrate Cellulose degradation aided by noncellulosomal cellulases & cellulosomes released into environment,Problems,Products other than ethanol or hyd
8、rogen are produced from cellulose.Clostridia are difficult to engineer.Cellulosome is extremely complex making its transplantation to another microbe a significant hurdle.,Goal,Improve yield of energy-rich molecules from cellulose Engineer the cellulosome into a genetically tractable microorganism (
9、e.g., Bacillus subtilis) Develop clostridium genetics to the point that extraneous metabolic reactions can be eliminated,Synthetic Biology,De novo design of biological entities Enzymes Biomaterials Metabolic pathways Genetic control systems Signal transduction pathwaysNeed the ability to write a blu
10、eprint,Why do we need synthetic biology?,Synthesis of drugs or other molecules not found in nature Designer enzymes Designer cells with designer enzymes or existing enzymes,Why do we need synthetic biology?,Energy production Production of hydrogen or ethanol Efficient conversion of waste into energy
11、 Conversion of sunlight into hydrogen,Why now?,Advances in computing power Genomic sequencing Crystal structures of proteins High through-put technologies Biological databases Diverse biological sampling/collection,Why here?,LBL has played a central role in the development of most of the technologie
12、s that will be essential for synthesizing new bacteria. Synthetic biology will leverage major LBL programs Joint Genome Institute Genomes-to-Life Advanced Light Source Molecular Foundry NERSC,Building a Super H2 Producer,Complex Polysaccharides,H2,Specialty & Commodity Chemicals,Ethanol,Building a n
13、ew chromosome based on genome sequences,Identification of minimal gene set,Maximizing renewable resource utilization,Specific aims,Determine chromosomal design rules and construct the basic superstructure for an artificial chromosome for our host organism. Determine the minimal number of genes neces
14、sary for a viable, yet robust bacterium.Determine the components of the cellulose degrading machinery necessary for cellulose utilization.,Integration with LBNL Projects,Joint Genome Institute Cellulose degraders sequenced by JGI and artificial chromosome sequencing. Genomes to Life Transcript and p
15、rotein profiling using GTL facilities. Molecular Foundry The cellulose degradation machinery as a model molecular motor. Synthetic Biology New initiative at LBNL and UCB.,Technical Challenges,Engineering a completely new organism is a daunting task.The cellulose degrading machinery is an incredibly
16、complicated molecular machine that will require significant characterization in its native host before it can be engineered into a new host.,Benefits to LBNL,Establish a new initiative in synthetic biology.Establish a new program in hydrogen/ethanol production.Utilize large sequence database from JGI.,
