Team:Monash Australia/Project


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== '''Overall project''' ==
== '''Overall project''' ==

Revision as of 05:47, 28 September 2010

Overall project Ethylene products we can relate to In simpler terms Experimental plan Results


Overall project

Monash University having a heavy movement to reduce the impact humans have on the planet has inspired our first iGEM project. After some initial research, we pondered on the concept of degrading plastics or cellulose into useable components. After discovering this has been a heavy focus by a number of different groups and past iGEM teams, so we then decidesd to look into producing some sort of useful product. After some investigation, we found that ethylene is a heavily used organic compound that is also naturally produced by plants. With our heavy reliance on this compound for plastics and in the food industry, we believe that it may be possible to develop a system that one day could be capable of replacing current production methods.

So what is ethylene used for?
Just about anywhere you go in the world you can find an ethylene based product. Just about everything you do today will have you come in contact or has come in contact with a ethylene based product. One of the most common ethylene based product is the water bottle. They come in all different shapes and sizes and can be found in every country in the world. Ethylene can be polymerised to create products such as; detergents, plasticisers, synthetic lubricants and additives, but also as co-monomers in the production of polyethylenes; Oxidised to create surfactants and detergents, and ethylene glycol; Halogenation and hydrohalogenation to produce products PVC, Polyvinylidene chloride and ethyl bromide; Alkylation to produce styrene; and itself used as a fuel source and to ripen fruit.

How do we make ethylene
To produce ethylene there is a huge requirement of energy, Ethylene is produced in the petrochemical industry by steam cracking. In this process, gaseous or light liquid hydrocarbons are heated to 750–950 °C, inducing numerous free radical reactions followed by immediate quench to stop these reactions (−157 °C). This process converts large hydrocarbons into smaller ones and introduces unsaturation. Ethylene is separated from the resulting complex mixture by repeated compression and distillation. The average ethtlene producing plant requires 34,000 kW cracked gas compressor, a 22,000 kW propylene compressor, and a 11,000 kW ethylene compressor, equating to a huge amount of energy required. Currently the main source of ethylene is from distilation of crude oil and natural gas, as well as catalytic steam cracking which precusors are again fossil fuels.

How do plants make ethylene
Plants also create ethylene. Ethylene is a plant hormone, which can induce plants to grow and fruit to ripen. in plants the biosynthesis of the ethylene occurs in three steps and starts with conversion of the amino acid methionine to S-adenosyl-L-methionine (SAM) by the enzyme SAM synthase. SAM is then converted to 1-aminocyclopropane-1-carboxylic-acid (ACC) by the enzyme ACC synthase. The final step involves the action of the enzyme ACC-oxidase to oxidiase ACC to ethylene.

So what are the more common items we can relate to?

Linear Low Density Polyethylene - Plastic wrap (and prank material)

Low Density Polyethylene - Soft Plastic Bottles

Medium Density Polyethylene - Pipes

High Density Polyethylene - Hard Plastic bottles

Ultra High molecular weight Polyethylene - Bullet proof vests

PVC (polyvinal chloride)- Pipes

Polystryene - Packing material and insulation (also prank material)

Polyethylene Glycol - Anti-Freeze

Experimental plan

We set out to attempt to use the plant ethylene synthesis machinery in e. coli to make e. coli into ethylene producing factories, therefore remove the need for the high energy steam cracking process and decrease the reliance of fossil fuels to produce ethylene. The main benefit of our design is that once the ethylene is captured, it can be directly feed back into exhisting petrochemical infrastructure, therefore economically speaking there would not be a need for job losses through finding a new source of ethylene.

Yang cycle
The Yang Cycle otherwise known as Methionine cycle is a biosynthesis cycle using methionine as a base molecule to produce several different products. We plan to clone three enzymes, SAM synthase, ACC synthase and ACC oxidase from plants and express them together in e. coli, with a methionine rich media in an attempt to produce ethylene producing e. coli.