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Revision as of 04:32, 28 October 2008

Attacking the plastic waste problem: a two-pronged approach

Faced with the issues of plastic waste accumulation and environmental pollution, a two-pronged approach with the potential to solve these problems has been developed. Firstly, biologically produced plastics such as polyhydroxyalkanoates (PHAs) are superior to petroleum-based plastics because they are both biodegradable and biocompatible. By focusing on modulating the ratio of two PHA monomers, 3-hydroxybutyrate and 4-hydroxybutyrate, the copolymer poly(3HB-co-4HB) can be created featuring increased elasticity and utility over any particular PHA monomer. Secondly, a novel polyethylene-degradation pathway is being engineered based on the oxidation of long-chain alkanes by alkane monooxygenase LadA. The region inhibiting the binding and catalysis of polyethylene has been computationally identified and site-directed mutagenesis is being conducted at this region to yield a mutant of LadA that oxidizes polyethylene and thereby increases its biodegradability. The combination of the production of an eco-friendly bioplastic with the degradation of petroleum-based plastics is a promising method of waste reduction.

Regulation of the synthesis of poly(3-hydroxybutyrate-co-4-hydroxybutryate) - Experimental

To be filled in soon

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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