From 2008.igem.org
Regulation of the synthesis of poly(3-hydroxybutyrate-co-4-hydroxybutryate) - Experimental
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Microbial Conversion of Polyethylene to Hydrocarbon Fuel
Polyethylene, the major component of plastic wares such as bags and jars, has widely been considered non-biodegradable, though recent studies have demonstrated that certain bacteria are able to metabolize polyethylene under specific conditions. (References)
Recent research in the field of synthetic biology has also revealed the capability of bacteria to synthesize replacement for crude oil and/or the various refined products of crude oil by synthesizing fatty acids--their energy storing medium--and removing the carboxyl group at the end by a decarboxylase, leaving a hydrocarbon that is the fuel. Companies such as LS9, Inc. and Amyris Biotechnologies have made great progresses in the field, to the point where they are able to engineer their bacteria to produce hydrocarbons according to their specifications.
Our project proposes the conjunction of both these processes: we, in essence, will try to engineer a bacteria (by modifying E. coli, as it seems at the present moment) to be able to metabolize polyethylene as its main carbon source, convert a significant quantity of the carbon into fatty acids, and express a decarboxylase gene so that it ultimately produces a hydrocarbon chain.
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Bio-removal of Nitroaromatic Compounds
Nitroaromatic compounds are widely used in the production of explosives, pesticides, plastics, dyes, pharmaceuticals, and petroleum products and are mutagenic, carcinogenic and highly stable and therefore pose an ever present and dangerious contaminant in the environment (Ye et al., 2004). Because many bacteria able to process these compounds are very specific, current research in the bioremediation of nitroaromatics is looking towards combining metabolic pathways in bacteria to degrade a wide range of these pollutants (Kulkarni et al., 2007). As of the current state, limited knowledge of degradation pathways inhibit this approach. Our approach is slightly different in that rather than biodegrading these compounds through combining existing pathways, we will attempt to have bacteria store these compounds within its membrane and then remove the bacteria from the contaminated site.
Because bacteria such as E. coli and other bacteria have been engineered to process these compounds (Kadiyala et al., 2003) we assume that these bacteria already have a method of transporting these compounds within the cytoplasm. Furthermore, E. coli produces nitroreductase, an enzyme that is present in many strains of bacteria and whose function is to reduces the nitro group in numerous metabolic pathways. In our project, we will attempt to engineer this enzyme so that it will bind irreversibly to the nitro groups of common nitroaromatic pollutants such as TNT and RDX. We will attempt to model this bond after the bond between carbon monoxide and hemoglobin.
After binding, the nitroaromatic compounds are then stored within the membrane of these bacteria. The removal of bacteria will be the subject of future research.
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References
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If it's green and it stinks, it's biology
If it blows up, it's chemistry
If it doesn't work, it's physics
-B. Gotwals
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