Scientists Engineer E.Coli to Produce Key Precursor of Spandex

Scientists Engineer E.Coli to Produce Key Precursor of Spandex

The Future: Bacteria Produced Hot Pants?

Scientists from the company Genomica have genetically engineered E.Coli to produce 1,4-Butanediol (BDO), a key chemical in the production of Spandex, clothing of choice for superheroes, glam rockers and 80’s disco enthusiasts.

The work, published in the journal Nature Chemical Biology, has the potential to drastically change the way BDO is produced. Currently one million metric tons are produced per year and all of this is derived from oil and natural gas. Almost half of the BDO produced globally is dehydrated to produce Tetrahydrofuran. This can then be polymerised to polytetramethylene oxide, the primary use of which is in fibres such as spandex.

The researchers faced several challenges whilst trying to produce their engineered bacteria. The first of which being identifying a synthesis mechanism, as there is no known naturally occurring biological synthesis pathway for BDO. Instead they had to compute all potential pathways from the typical E. coli metabolites to BDO. The computer algorithm they used  identified over 10,000 four-six step pathways that could result in synthesis of BDO from common metabolites, including acetyl-CoA, succinyl-CoA and glutamate.

These methods were then narrowed down based on theoretical yield, pathway length and thermodynamic feasibility. After this they picked out the following pathway as the best way for E.Coli to produce BDO:

The BDO synthesis pathway. Each number indicates an enzyme: (1) 2-oxoglutarate decarboxylase; (2) succinyl-CoA synthetase; (3) CoA-dependent succinate semialdehyde dehydrogenase; (4) 4-hydroxybutyrate dehydrogenase; (5) 4-hydroxybutyryl-CoA transferase; (6) 4-hydroxybutyryl-CoA reductase; (7) alcohol dehydrogenase. Steps 2 and 7 occur naturally in E. coli, whereas the others are encoded by heterologous genes introduced in this work.

With an elucidated pathway, then came the challenge of how to get a bacterium to carry it out. Not all the enzymes required for the pathway are present in the wildtype E.Coli. As a result of this, the group identified several different mechanisms for generating the intermediate 4-Hydroxybulymate (4HB) settling on; the addition of three genes sucCD (E. coli), sucD and 4hbd (P. gingivalis).

The final stage in the process, 4HB to BDO, also required some manipulation. The change requires two reduction steps, catalyzed by dehydrogenases. This can occur by the addition of exogenous 4HB to wild-type Clostridium acetobutylicum. However, for efficient production they needed to have the process contained within E.Coli. So instead  they expressed the 4-hydroxybutyryl-CoA transferase (cat2) gene from P. gingivalis for the conversion of 4HB to 4HB-CoA. The final stages then involved the action of  4-hydroxybutyryl-CoA reductase and the native alcohol dehydrogenase, finally resulting in a viable BDO product.

Whilst this discovery does not directly result in the production of spandex or other useful fibres by bacteria. This could prove to be an efficient and environmentally friendly way to produce crime-fighting and disco outfits at some point in the future!

Body for sale: How much are your chemical components worth?

Body for sale: How much are your chemical components worth?


Are we made of money?

You always hear stories about students selling their bodies to finance their studies. But, how much could you make from the raw materials that makes up your body? This was an idea that came to me the other day and I decided I had to find out just how much we are worth in raw chemical elements!

To work this out I first needed to find out what the make-up of my body is. Unsurpringly, the internet already had this data assembled for me. The average human is made up of 54 different elements, ranging from carbon (the most prevalent) to radium (the least prevalent). Then find the cost for the pure element, this was done with a variety of sites (but mainly chemicool.com). All the following calculations and data are relevant for an adult of approximately 70Kg, the data offers no distinction between men and women. But, due to the natural differences in body tissue composition it is likely that there will be some variation. Here are the 15 most abundant elements in the body and their real world cost values:

Element Mass in body (kg) Value per kg ($) Total value ($)
Oxygen 43 3 129
Carbon 16 24 384
Hydrogen 7 100 700
Nitrogen 1.8 4 7.2
Calcium 1.0 200 200
Phosphorus 0.780 300 234
Potassium 0.140 1000 140
Sulphur 0.140 500 70
Sodium 0.100 250 25
Chlorine 0.095 1.5 0.14
Magnesium 0.019 37 0.7
Iron 0.0042 72 0.3

This comes up to the total of $1890.34. But, what about the remaining 39 elements? The body contains a remarkable range of elements from gold to uranium. However, with their quantities so low it only works out as only $95.41.

Giving the grand total cost of the human body as $1985.77.

According to current conversion rates is about £1224.72. What could you buy for this though? Well, you could get a lower end Macbook Pro, 2722 Mars bars or you and 7 friends could all chip in to buy the latest Fiat 500…I know which I would pick!

To check out all the calculations you can download my excel workings from here

Viral Science: Golden Retrievers Explain Physics

Viral Science: Golden Retrievers Explain Physics

Ever thought there were too few pets in science classes at school? Well this video will set that straight. This was originally produced by NewScientist as an experiment in whether or not they could make a viral video about science, it was circulated for several months before they revealed they produced it.

Top 5 Science Fail: Number 1 – Thomas Midgely Jr and Planet Earth

So here it is, the number 1 fail. I chose the career of one particular scientist for this, and I think you will see why. To see the rest of the top 5 click below:

Number 5

Number 4

Number 3

Number 2

Number 1: Thomas Midgely Jr. and Planet Earth

As we go through our lives most of us as individuals will have minimal net affect on our planetary ecosystem.  Maybe some will rise to high positions in companies where the decisions made might have a more substantial impact. But, none of us are likely to have quite such a big affect as Thomas Midgely Jr.

Thomas Midgley Jr.

Born in the state of Pennsylvania in 1889 he was a Chemist and Mechanical Engineer, who in 1916 joined the General Motors company (GM). At the time Midgely joined the company one of the key problems facing car manufacturers was ‘engine knocking’, which occurs when the petrol auto-ignites in the engine damaging it. Midgely realised that if you put lead related compounds into the petrol then this eradicated the problem. As a result of his discovery adding tetra-ethyl lead (TEL) to petrol become common practice. However, problems began to emerge as workers and researchers including Midgely became ill with lead poisoning. Culminating in Midgely holding a conference to defend his work in 1924. To show how safe TEL was he poured it all over his hands and spent 60 seconds inhaling its fumes. He spent the next year recovering from lead poisoning due to this stunt (which was kept quiet from the media).

Lead poisoning due to TEL was a large global problem and it wasn’t until the 70/80’s that leaded petrol began to be phased out. This discovery alone would probably have been enough to have gotten Midgely on this list. However, Midgely also helped make another discovery which has helped him claim the top stop.

In the 1920’s whilst still working for GM he was asked to find a replacement to the toxic and flammable refrigeration compounds (such as ammonia) which were at the time being used. This could have brought about redemption for Midgely. He and his team focused on the halogens due to their volatility and inertia. The decided to combine fluorine with hydrocarbons, and in 1930 created Freon, the worlds first chloro-flouro-carbon (CFC).

The team were delighted with their discovery. Midgely, echoing his TEL display,  demonstrated its capabilities by inhaling it and then blowing out a candle. Midgely received awards for his discovery and CFCs replaced the existing refrigerants in several usages.

Tetra-ethyl lead (TEL) containing petrol

It wasn’t until the 1980’s that people began to realise that the CFCs were breaking down in the atmosphere and through free-radical action were destroying the O-zone layer. By this time Midgely had long been dead, he contracted polio in 1940 and invested a system of pulleys and ropes to enable him to get out of bed. This invention backfired on him personally as one day he became entangled in the ropes and suffocated.

Midgely’s inventions have been summed up particularly well by JR McNeill an environmental historian who said that Midgely ‘had more impact on the atmosphere than any other single organism in Earth’s history’.

I hope that you have enjoyed my list of Top 5 Science Fails, if you disagree with any of my selections or have any more you think I should know about feel free to comment below.