Team:DeNovocastrians/Implementation




Implementation

The DeNovocastrians had two goals for iGEM:
1) Engineer microorganisms to break down toxic pollutants in the environment.
2) Construct a biosensor that could be utilised by companies and researchers alike to detect petrochemicals in the environment.

As we saw in the crisis unfolding in Mauritian waters, a ship filled with petrochemicals ran aground and leaked its oil contents, devastating the local oceanic ecosystem and its human, animal and microbial inhabitants. Petrochemical pollution harms a range of marine and terrestrial environments in the world today. The petrochemical benzene, for example, is listed as a Group 1 carcinogen by The International Agency for research on Cancer (WHO, 2010). It has broad impacts on natural environments and is harmful to all kinds of creatures, including humans.
Now, imagine a world where a rapid response team arrive and release the engineered microorganisms into these polluted environments. These organisms would degrade the harmful pollutants, remediating the ecosystem before significant damage can occur. That’s the world we DeNovocastrians want to live in!


(Left: "Rena oil spill”, by WikiWand/Environmental law, licensed under CC BY 3.0. NZ)
(Right:"Protecting natural water sources”, by Flickr/Nestle, licensed under CC BY-NC-ND 2.0)

The biosensor we created would initially be useful in the rapid detection of these pollutants and identifying environments that require the greatest remediation. Our biosensor would be dispatched in disaster situations to monitor an environment for pollutants, it would work like this:
1) Upon environmental contamination by a pollutant such as benzene. Scientists would release our engineered microbes.
2) In the presence of petrochemicals, our engineered microbes would glow green due to pollutants binding transcriptional elements upstream of a GFP gene.
2) When our engineered microbes break down the petrochemical pollutants, our microbes will glow red due to products binding transcriptional elements upstream of an mCherry gene.

These synthetically-engineered bacteria break down the benzene into simpler molecules (such as Acetyl-CoA), molecules which are later used to create energy for themselves through the Krebs cycle. In the future, other degradation gene clusters could also be inserted into these microorganisms. This would allow more complex poly-cyclic-aromatic hydrocarbon pollutants to be broken down- pollutants that are notoriously recalcitrant in the environment.

The correct bacterial system to use in a bioremediation project would depend on the environment in question. For example, terrestrial environments with a low oxygen content or aquatic sediments would utilise anaerobic microbes, harsh terrestrial environments would use an extremophile. Ships leaking petrochemicals into the sea (like the one seen in the Mauritius) would employ aquatic microbes such as the Synechocystis Cyanobacteria we characterised ( "Results: Future targets...") for growth in our project. The desired organism suited to a particular environment needing to be remediated, would be inserted with the degradation genes (benABCDE) we have used in our project.

Further bacterial engineering would implement a "kill-switch" as a safety consideration and preservation of the ecosystem to be remediated. Our engineered bacteria are dispersed in an environment polluted with petrochemicals and degraded by their inserted benABCDE gene clusters. As the pollutants are degraded, the preferred carbon source is depleted, leaving no way for the bacteria to make energy for themselves and leading to death.

In summary, we will have created a way for bacteria to alert us to the presence of the pollutant benzene, and, we will have engineered these bacteria to break-down these harmful pollutants into energy intermediates. By the end of the project, we hope to have helped the world take a small step towards a cleaner and greener planet!


References

W.H.O. (2010). https://www.who.int/ipcs/features/benzene.pdf . Geneva, World Health Organization. 1-3.