PubhD #30: Anti-Bacterial Resistance, Wetlands and Sustainable Chemistry

31 August 16 words: Gav Squires
At each PubhD event, three researchers from any subject area explain their work to an audience in a pub in exchange for a drink or two. The talks are at a "pub level"
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First up is Jonny who is researching anti-bacterial resistance.

Anti-bacterial resistance is a huge problem; by 2050 it will be responsible for more deaths than cancer and it also makes some surgeries very difficult. An awful lot of antibiotics are used in animals. In the US, there is around 70% more usage in animals than there is in humans (in Europe, it's about equal). Farmers are pensive as diseases can spread very quickly. In the 1950s, clinical amounts of antibiotics were used to encourage growth in pigs. This can increase the yield by as much as 10 Euros per pig.

Swine dysentery is a wasting disease that leads to bloody diarrhoea. No-one will touch a farmer's pig while they have swine dysentery and the only cure is antibiotics. Swine dysentery was first documented in the 1920 and is an endemic disease. Johnny is investigating what is happening with the disease in the UK - gene sequencing DNA from 11 years' worth of data. How does it compare with the rest of the world?

Some of the swine dysentery is UK-based, while some is also seen in Europe. Did it come to the UK from Europe or did it spread to Europe from the UK? There seems to be a low level of anti-bacterial resistance in the UK but it does seem to be increasing. We still don't know which mutations cause anti-bacterial resistance. We know that plasmid mutations are worse that chromosome mutations. A plasmid is an "extra bit of DNA" and it can spread anti-bacterial mutation between species.

Key learning: The antibiotics used to treat swine dysentery aren't used on humans.

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Next we have Theo, who is using magnetic resonance probes to check the health of constructed wetlands.

Wetlands are built to treat water - they are not as effective as chemical treatment but they are much more ecologically friendly. In Australia, they have been used since 1904 but only really started gaining popularity in the 1950s. A base material such as gravel is stored in a pit that is coated so that the water doesn't just seep out. Dirty water is fed in and it flows through the gravel to come out clean. Often there is a reed bed growing in the pit. All of the nasty stuff in the water is filtered out by the gravel and killed by sunlight and the micro-organisms that live in the gravel.

It was originally thought that these wetlands would last for 100 years, but they started getting clogged up after only 10. It's possible to fix this by cleaning the gravel but you need to know when it is going to need cleaning. To do this you can time the period it takes the water to flow through the system, however this isn’t particularly useful or efficient.

A better way is to use a magnetic resonance probe, which takes a relaxation measurement. The probe contains two magnets and a copper coil to collect the signal. Water molecules have a "magnetic moment" - it aligns with a magnetic field. Using the coil, a current is applied and the signal collected. As the magnetism starts to dephase, the water relaxes back to its base field. As the particulates build up in the gravel, it takes less time for the water to "relax" so it's possible to tell how close the gravel is to needing to be cleaned. The probes themselves are so cheap that they are left in the gravel forever.

Key learning: it takes 1 chemical treatment and two constructed wetland treatments to make drinkable water.

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Finally, we have Jonny (a different Jonny) who is researching sustainable chemistry.

The earth can sustain approximately one quarter of the people on it. How can we support the other three quarters in a more environmentally friendly way? Phot-chemistry is making light to create chemicals. It's far more sustainable than things such as thermal chemistry and you can use the sun, which is far less environmentally damaging.

Now, it's about trying to do this on a really huge scale - a crossover between chemists and chemical engineers. Trying to make chemicals really quickly in a more energy efficient way with more throughout. But you have to keep an eye on what is happening to the reaction in real time. If you make your product but continue to add light, then you can end up making something that you don't want to make.

At the moment the focus is on making oxetane rings. This can then be opened in many different ways and so can make a lot of different things in downstream processes. The long term plan is to make tonnes of the stuff. One example of where this can be used is in anti-malarial drugs. At present these are manufactured using a solvent that is highly toxic. Instead, using phot-chemistry, it can be made from CO2

Key learning: In the 1960s, pho-chemistry was an "explosion waiting to happen"

PubhD will return to the Vat & Fiddle at 7.30pm on the Wednesday 21 September where there will be talks on Education, Classics and History.  

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