Team:Nantes/Description
Project Background
As every iGEM team, we went through a brainstorming phase in order to choose the project that would take us far in the adventure. Many interesting ideas came out of it, but many of them had already been developed by previous teams. We wanted to stand out. It was then natural for us to turn to a local topic that particularly affects our region: the green tides.
For over 40 years, Brittany coastlines have been invaded by green macro-algae Ulva blooms, known to the public as "green tides". This abundance of green algae on the beaches extends from year to year on the French northwestern coasts but also in other countries around the world. As the only team in the West of France, we felt it was justified to explore the issues caused by green algae every year.
Our project was born out of the health problem caused by green tides. Indeed, stranded algae dry quickly in the sun to gradually form an impermeable layer. Under this layer, the algal tissue enters an anaerobic decomposition phase. Some bacteria will use the sulfate naturally present in the cell walls of the Ulva to produce H2S. In absence of dioxygen, the bacteria use R-SO3 groups as a substantial source of oxygen, and it is also an oxidative compound for widespread metabolic reactions. Dihydrogen sulfide is very toxic for organisms and consequently for humans. This toxicity is responsible for several deaths: domestic dogs, horses, humans [1]. We wanted to take advantage of bacteria’s ability to produce gas.
Furthermore, we had been encouraged by a publication on the CNRS website: "Exploiting green tides thanks to a marine bacterium"[2]. A very attractive title ! This announcement was based on a scientific article published in 2019. Researchers had discovered an enzymatic system that allows the decomposition of ulvan into high-value molecules[3].
Synthetic biology was going to help us to optimize the valorization of green algae using these discovered enzymes.
For over 40 years, Brittany coastlines have been invaded by green macro-algae Ulva blooms, known to the public as "green tides". This abundance of green algae on the beaches extends from year to year on the French northwestern coasts but also in other countries around the world. As the only team in the West of France, we felt it was justified to explore the issues caused by green algae every year.
Our project was born out of the health problem caused by green tides. Indeed, stranded algae dry quickly in the sun to gradually form an impermeable layer. Under this layer, the algal tissue enters an anaerobic decomposition phase. Some bacteria will use the sulfate naturally present in the cell walls of the Ulva to produce H2S. In absence of dioxygen, the bacteria use R-SO3 groups as a substantial source of oxygen, and it is also an oxidative compound for widespread metabolic reactions. Dihydrogen sulfide is very toxic for organisms and consequently for humans. This toxicity is responsible for several deaths: domestic dogs, horses, humans [1]. We wanted to take advantage of bacteria’s ability to produce gas.
Furthermore, we had been encouraged by a publication on the CNRS website: "Exploiting green tides thanks to a marine bacterium"[2]. A very attractive title ! This announcement was based on a scientific article published in 2019. Researchers had discovered an enzymatic system that allows the decomposition of ulvan into high-value molecules[3].
Synthetic biology was going to help us to optimize the valorization of green algae using these discovered enzymes.
From there, our A3 Project was born.
Our initial objective is to produce sulfuric acid from the accelerated degradation of Ulva spp. algae collected from the shoreline.
For this purpose, three degradation enzymes [3] will be expressed in an Escherichia coli BL21 (DE3) chassis suitable for overexpression. These enzymes effectively degrade the major component of the wall of these algae: ulvan, a highly sulfated polysaccharide representing 38-54%[4] of the dry weight of the Ulva.
In the meantime, modified E. coli will produce three sulfatases [3] to promote the release of sulfate SO42- from ulvan degradation. To enable the activation of these sulfatases, the Formylglycine-generating enzyme (FGE) will be expressed. This enzyme cocktail will be stored in a tank until the algae are freshly collected and transported.
Once the accelerated degradation of the ulvan and the release of sulfates achieved by the previous enzymes has been completed, we will transform SO42-into hydrogen sulfide (H2S). This reduction will be possible by the presence of sulfate-reducing bacteria (SRBs), which are naturally present in the collected algae blooms.
Finally, from the hydrogen sulfate, sulfuric acid (H₂SO₄) will be produced by chemical conversion.
For this purpose, three degradation enzymes [3] will be expressed in an Escherichia coli BL21 (DE3) chassis suitable for overexpression. These enzymes effectively degrade the major component of the wall of these algae: ulvan, a highly sulfated polysaccharide representing 38-54%[4] of the dry weight of the Ulva.
In the meantime, modified E. coli will produce three sulfatases [3] to promote the release of sulfate SO42- from ulvan degradation. To enable the activation of these sulfatases, the Formylglycine-generating enzyme (FGE) will be expressed. This enzyme cocktail will be stored in a tank until the algae are freshly collected and transported.
Once the accelerated degradation of the ulvan and the release of sulfates achieved by the previous enzymes has been completed, we will transform SO42-into hydrogen sulfide (H2S). This reduction will be possible by the presence of sulfate-reducing bacteria (SRBs), which are naturally present in the collected algae blooms.
Finally, from the hydrogen sulfate, sulfuric acid (H₂SO₄) will be produced by chemical conversion.
Why produce sulfuric acid? It is by far the most widely used industrial chemical. It is used in many industrial sectors and to synthesize many products, such as fertilizers, pigments, explosives, detergents, synthetic textiles and oil refining. [5, 6, 7, 8]
Although our project is aiming at a successful outcome for the industry, we don’t wish to see the formation of green tides become sustainable. That is why we will also work on green algae from seaweed farming.
To conclude, The A3 project tends to evolve according to the experiments and achievements of our team. It is a project that promises great surprises for 2021.
Although our project is aiming at a successful outcome for the industry, we don’t wish to see the formation of green tides become sustainable. That is why we will also work on green algae from seaweed farming.
To conclude, The A3 project tends to evolve according to the experiments and achievements of our team. It is a project that promises great surprises for 2021.
What did we do?
How Covid 19 impacted our project?
The pandemic has strongly limited the construction of our project due to the lockdown but also because of the restrictions that followed and that are still in effect today.
The team was created not long before the lockdown in March. Therefore we didn't have the opportunity to share moments and to create bonds between members. : the team-building was challenged. Nevertheless, we did not give up. At the time, we were using social networks, Google Workspace, email, phone and video conferencing. But it was a real challenge to organize ourselves over distances.
The scientific unit was not able to experiment in the laboratory for this 2020 edition. However, moving from theory to practice is what makes a scientific project real. Research is not done without experiments. For this reason, it was difficult to test our hypotheses to allow the project to grow more quickly. It was also a disappointment for our members who have a taste for the lab bench. For the members of the HP group, enriching face-to-face meetings and human contact with the public has been very limited. The HP unit has seen some events canceled. Visits and meetings in the field, essential for the Integrated HP, could not take place. Everything had to be rethought. Even after lockdown, the restrictions advised against interaction with the public. Thus, we were slowed down, and that's still the case at the time of writing. That's why every idea had to and must be applied in the virtual world. As for the financing unit, it had to face new economic challenges. Companies were indeed less willing to subsidize our project because of the general crisis.
Although the meetup cancellations, the announcement of the competition by distance and the prohibition of access to the laboratory could have been demotivating, our team was still able to show optimism. Continuing our project for 2021 is a chance for us to go even further and realize original ideas for the iGEM competition.
The team was created not long before the lockdown in March. Therefore we didn't have the opportunity to share moments and to create bonds between members. : the team-building was challenged. Nevertheless, we did not give up. At the time, we were using social networks, Google Workspace, email, phone and video conferencing. But it was a real challenge to organize ourselves over distances.
The scientific unit was not able to experiment in the laboratory for this 2020 edition. However, moving from theory to practice is what makes a scientific project real. Research is not done without experiments. For this reason, it was difficult to test our hypotheses to allow the project to grow more quickly. It was also a disappointment for our members who have a taste for the lab bench. For the members of the HP group, enriching face-to-face meetings and human contact with the public has been very limited. The HP unit has seen some events canceled. Visits and meetings in the field, essential for the Integrated HP, could not take place. Everything had to be rethought. Even after lockdown, the restrictions advised against interaction with the public. Thus, we were slowed down, and that's still the case at the time of writing. That's why every idea had to and must be applied in the virtual world. As for the financing unit, it had to face new economic challenges. Companies were indeed less willing to subsidize our project because of the general crisis.
Although the meetup cancellations, the announcement of the competition by distance and the prohibition of access to the laboratory could have been demotivating, our team was still able to show optimism. Continuing our project for 2021 is a chance for us to go even further and realize original ideas for the iGEM competition.
References :
- [1] Conference by Alain Menesguen, researcher at Ifremer / Green Tides in Brittany : Causes and Remedies - a conference for the general public at Ifremer Bretagne
- [2] http://www.cnrs.fr/fr/exploiter-les-marees-vertes-grace-une-bacterie-marine
- [3] Reisky L, Préchoux A, Zühlke M and al. A marine bacterial enzymatic cascade degrades the algal polysaccharide ulvan. Am Nature Chemical Biology, (2019), 15(8).
- [4] Lahaye, M., & Robic, A. (2007). Structure and functional properties of ulvan, a polysaccharide from green seaweeds. Biomacromolecules, 8(6), 1765-1774.
- [5] Agency for toxic substances and disease registry, Toxicological profile for sulfur trioxide and sulfuric acid. ATSDR. Research Triangle Park, NC : Research Triangle Park. (1998). [MO-019836], Microfiche : PB99-122038 http://www.atsdr.cdc.gov/toxprofiles/
- [6] Bohnet, M. et al., Ullmann's Encyclopedia of Industrial Chemistry. 7th. Wiley InterScience (John Wiley & Sons). (2003-). http://www3.interscience.wiley.com (http://www3.interscience.wiley.com/cgi-bin/mrwhome/104554801/HOME)
- [7] Kirk-Othmer encyclopedia of chemical technology. 4th ed. New York : John Wiley & Sons. (1991-1998). [RT-423004]
- [8] Lewis, R.J., Sr., Hawley's condensed chemical dictionary. 14th ed. New York : John Wiley & Sons. (2001). http://onlinelibrary.wiley.com/book/10.1002/9780470114735
igemnantes2020@gmail.com