Human practices
Introduction
Our synthetic biology project was driven by our desire to address the pressing issue of microplastics pollution in water bodies. Many projects had already been designed to degrade the microplastics present in the environment, and we wanted to develop a different approach. We therefore decided to take a different direction, by devising a solution that would enable us to capture them using engineered Escherichia coli biofilm. We contacted several experts in the field of microplastics and biofilm to get their feedback and advice on our project.
Background research & interviews with experts in the field
ASL
Why we contacted them:
At the beginning of our project, it was essential for us to turn to associations that deal with water protection in Switzerland and ask them about the current situation concerning microplastics. These associations take concrete action on site through a variety of initiatives, thereby contributing to real improvements and changes, and therefore have a very informed view of the situation. ASL (Association de Sauvegarde du Léman) is a french-swiss not-for-profit organization whose aim is to take action and raise awareness of issues concerning water quality and, more in general, lake Geneva. We met with Alexis Pochelon, their project manager for issues relating to plastics and biodiversity. He is passionate about lake Geneva, and carried out his research project on nanoplastics.
Key points of the interview:
This interview made us more aware of the regulatory aspects of releasing GMOs in natural environments and the
importance of taking them into consideration. Mr Pochelon gave us advice on how to implement our project,
pointing out that employing our biofilm directly in the lake would be more complicated than we had imagined,
and helped us to redirect our idea towards implementation in wastewater treatment plants (WWTPs).
Having access to data on the flow through the WWTP would allow us to measure the difference in microplastic
concentration in the water before and after passing through the biofilm. These important measurements would be
more difficult to carry out in the lake settings.
We also shared with him our intention to organize a waste collection activity, to engage people and raise awareness.
He helped us to identify the best spot for the activity and provided us with a new exciting perspective.
He introduced us to the ASL participatory science project, which we decided to contribute to by collecting data
on each piece of waste collected, and entering it in their database. → See “project, waste collection”
Prof. Knut Drescher
Why we contacted him:
As we were working with biofilms, it was essential for us to be able to discuss our project with an expert in the field,
in order to obtain feedback and guidance for our laboratory work. Prof. Knut Drescher is the head of a research group
working on bacterial biofilms at the University of Basel.
Their research group focuses on the investigation of emergence in time and space of bacterial multicellular structures such
as biofilms, and the properties and functions they display in response to different factors.
Key points of the interview:
This interview gave us extremely valuable insights about the technical and practical aspects to consider when working
with bacteria that produce biofilm. Prof. Drescher suggested several ways of growing our biofilm under different conditions.
Additionally, he also gave us precious advice on how to quantify and detect the microplastics captured, as well as how to
recover them at the end of the process. Furthermore, we discussed how to recover or dispose of the microplastics once the
biofilm is recovered. He recommended not to use denaturation techniques, as the curli fiber is very stable; according to him
the best option would be to burn the biofilm.
We also discussed the different implementation ideas we had for our biofilm. Despite the disadvantages that an implementation
in WWTPs can present, Prof. Drescher noted that we could transfer our plasmid into bacteria that are already present in one
of the stages of the WWTP.
Prof. Denise Mitrano
Why we contacted her:
We contacted Prof. Dr Denise Mitrano, who works as an environmental analytical chemist, and whose work focuses on the distribution and impacts of anthropogenic materials in environmental systems. In particular, we wanted to ask her if we could get samples of textile fibers.
Key points of the interview:
She gave us some useful advice regarding what to take into account when testing biofilm, as well as how to prepare samples and how much microplastics to add to the biofilm for testing. She very kindly sent us samples of textile fibers to use during the testing phase. Prof. Mitrano pointed out that the fibers were long, which would require us to cut them into smaller particles so that we could use them for our testing. We then received several suggestions from her about testing. Firstly, she suggested that we test our biofilm under different water flow rates, as this is likely to have a significant impact on the biofilm's ability to capture microplastics. Secondly, she recommended that, for our exploratory experiments, we use higher concentrations of microplastics than those found in the environment. Finally, she advised us to check the staining of the microplastics with Nile red in the water, to ensure that the stain was water-resistant and could still be visualized and analyzed.
Dr. Florian Breider
Why we contacted him:
We decided to contact Dr. Florian Breider, the head of the Central Environmental Laboratory unit at EPFL. His research interests concern the origin and the fate of contaminants in aquatic environments, soils and sediments.
Key points of the interview:
After learning about our project, Dr. Florian Breider pointed out that it was important to take into account the presence of additives in microplastic particles, especially in tyre particles. These can be highly charged, and their release could disrupt the biofilm. It is also worth paying similar attention to the additives that different types of plastic may contain. We then asked him what type of analysis he used in his research, and what type of analysis he could recommend to analyze the samples of microplastics captured by our biofilm. In his opinion, the most appropriate method for us would be the quantum cascade laser (QCL), which would enable us to obtain information on the size and type of polymer of the different particles in the sample, among other things. He also warned us about the difficulty of detecting fibers with this method. The undulation of the fibers prevents them from being observed at the same focal plane, which means that there is a risk of a single fiber being falsely detected as several different fibers. Regarding the tyre particles, we would need to know whether they have been manufactured by being cryogenically frozen and then ground, as they differ greatly in shape from the tyre particles that can be found at the side of the road as a result of tyre abrasion. Finally, he pointed out that identifying the ideal implementation might be complex, because the efficiency of the biofilm would strongly depend on the hydrodynamics of the place where it would be placed. We would therefore need to ensure that the biofilm is sufficiently resistant to the current and the flow of water that it could be exposed to.
Engagement with communities
Waste collection day
In addition to our laboratory project, we wanted to act on the issue we decided to focus on and make a meaningful
contribution outside of academic settings. We came up with the idea of a plastic waste collection initiative.
Even though our project is targeting specifically microplastics, the collection difficulties of this category of plastic,
notably their small size, made us consider all types of plastic waste for the collection. This way, we can make our own
contribution by tackling littering, one of the main sources of microplastic pollution.
During our interview with Alexis Pochelon, we exposed our idea of a waste collection and asked for his advice as the ASL
association had previous experiences in this type of action. → see human practices ASL
He recommended a collection site, which is where we actually carried out our waste collection. Additionally, he also told us about
Net'Leman,
an application created by ASL, which collects data on litter to better understand where it originated from and to find solutions
to prevent it. By collecting this type of data, ASL can draw up accurate statistics and gain a better understanding of the waste
flow in the Lake Geneva region. The aim of this application is to involve civil society in spontaneous or organized collections of
waste. The data will then be incorporated into scientific studies which, in turn, allow to adapt information and awareness-raising
campaigns on the subject.
Based on these recommendations, we decided to add a new dimension to our initial idea of waste collection by adding this aspect of
participatory science, and also by involving volunteers. Contributing to the reduction of littering pollution was already of
extreme importance for us, but going a step further by being able to help scientific research to progress added meaning and
usefulness to our action.
With the help of several people who came to help us, we collected 8 kg of rubbish on the shores of Lake Geneva.
We then proceeded to separate the contents of all the bags, trying to sort the waste we had collected as accurately
as possible into the various categories. As plastics are not the only waste being thrown away, we obviously collected
all types of rubbish we found.
Conclusion
The interviews and waste collection activity that we were able to conduct were very useful and gave us a better overview of the microplastics situation. They confirmed that it is essential to find solutions to tackle this issue. In addition, we received precious advice on the technical and practical aspects to be considered when working with bacteria producing biofilm, along with the methods to be used to test its efficiency in capturing microplastics. The concern about release of GMOs in the environment has been raised and discussed during these interviews, which better shape our implementation ideas to minimize this problem.
Communication
Swiss-UK Synthetic Biology conference
We had the unique opportunity to present a scientific poster at the Swiss-UK Synthetic Biology Conference 2023, held at the University of Lausanne. The aim of this conference is to present the world-leading synthetic biology research emerging from the UK and Switzerland. We were thus able to present our project to an audience working and doing research in the field of Synthetic Biology. It was an enriching experience to be among other scientists and to have the opportunity to discuss our project with some of them.
Integrated human practices
Initial project design
Interactions with various experts in the fields of microplastics and bacterial biofilms
were crucial to ensure the successful realization of our project, in order to effectively
tackle the problem of plastic pollution. Based on interactions with experts and our brainstorming,
our initial plan was to induce overexpression of the curli fiber in a strain of E. coli to overproduce biofilm.
Leveraging the natural adhesive properties of this natural biomaterial, we aimed to bind all types of microplastics.
To confirm that our project can address the microplastic issue in a real-life setting, we interacted with
practitioners and stakeholders who are involved in the management of microplastics in Swiss waters.
These interviews gave us valuable advice on how to carry out our project, but some led us to question our initial approach.
Thanks to these discussions, we reshaped and evolved several aspects of our proposal, and gave it a new direction,
so that it could be more effective and suitable for solving real-world issues.
Stakeholder feedback
Prof. Bernd Nowack
Why we contacted him:
Prof. Dr. Bernd Nowack works for the Swiss Federal Laboratories for Materials Science and Technology (EMPA), and we decided to contact him for his expertise in assessing the environmental hazards of microplastics, and in experimental research into the release of microplastics from textiles.
Key points of the interview:
We first explained to him our initial plan of inducing overexpression of the Curli fiber in a strain of E. coli to overproduce biofilm. Leveraging the natural adhesive properties of this natural biomaterial, we aimed to bind all types of microplastics. However, Prof. Nowack pointed out the specificity issue, explaining that not all types of plastics are equally represented. Therefore he advised us about the importance of targeting plastic most commonly found, namely polypropylene (PP) and polyethylene (PE).
He also gave us some valuable advice on the samples to use for testing. He suggested samples collected directly from the lake, as commercially available microplastics are not generally representative of the shapes of microplastics that can be found in the environment.
We then turned to the subject of implementation by explaining our ideas. In his opinion, it would be wiser to take action at lake level, as the greatest quantities of microplastics would not necessarily be found in the wastewater passing through the WWTPs.
Mr. Pascal Hagmann, director of Oceaneye
Why we contacted him:
Oceaneye is a Swiss not-for-profit organization whose aim is to help raise public awareness on plastic pollution of water,
its causes and effects, and to contribute to scientific research by conducting campaigns to collect and analyze samples of ocean surface water.
Given the divergent opinions we had received regarding the implementation of our project, we wanted to ask for their
opinion and advice regarding a potential real-world application for our biofilm.
Key points of the interview:
Since oceaneye has carried out multiple water analyses in several regions of the world,
we wanted to have Mr. Hagmann global vision on the problem. For example, we wanted to know
in which parts of the lake the most microplastics were found (on the surface, at the bottom, etc.).
Mr. Hagmann explained that a lot of microplastics accumulate at the bottom of the lake, although a minority
of types of plastic float on the water surface.
As we received divergent advice on the implementation of our project, we also wanted to get his feedback
on the different ideas we had. Concerning the idea of attaching the biofilm to the underside of boat hulls,
Mr. Hagmann told us that this would probably be very ineffective, not only because the boat would create a water
movement that could push the particles away from the surface, but also because, as he mentioned earlier,
the density of microplastics is not very high at the surface of the water. His advice was therefore to work
as far upstream as possible, and try to retain the microplastics in order to stop or at least reduce their accumulation in the lake waters.
While discussing the implementation, Mr. Hagmann brought up the subject of tyre particles, which generally flow directly
into the lake, bypassing the WWTPS. We were not aware of the scale of the problem represented by tyre particles.
So we took on board this very important information, and decided to take direct action to target this problem.
Finally, we asked him if he had any samples of microplastics directly from the lake, and if he would be willing
to send us some real samples of microplastics to be tested with our biofilm.
Epuration région Morgienne (ERM) STEP
Why we contacted Ms. Caroline Villard & Mr. Denis Hostettler:
The possibility of implementing our project in WWTPs was quickly raised during the brainstorming process. However, we had only a vague idea of how wastewater was actually treated, and above all how they dealt with the management of the pollutants present in it, including microplastics. In order to get a clearer picture and to be able to refine our implementation proposal, we contacted the Epuration région Morgienne (ERM). We were fortunate enough to be received on site by the director, Ms. Caroline Villard, and the head of operations at the STEP, Mr. Denis Hostettler, and were able to visit the WWTP.
Key points of the interview:
With Ms. Villard and Mr. Hostettler, we discussed how the WWTP works, and how the wastewater is treated.
In addition, we wanted to know how they manage the microplastics present in the wastewater.
Ms. Villard and Mr. Hostettler explained that there are no treatment systems that specifically
target microplastics but that most of them are retained in the mud, which is then treated, dried and burnt.
Additionally they told us that there are actually no techniques to quantify the amount of microplastics released in the outflow water.
Similarly to previous interviews, they raised the problem of tyre particles, which do not pass through WWTPs,
as they are carried along by road water and discharged directly into the lake. They explained that there are
filters under the road grates, but, unfortunately, these are not designed to capture tyre particles.
→ see implementation
Ms. Marly Levene, head of business development at Depoly
Why we contacted her:
DePoly, a young Swiss company, aims to create a sustainable circular economy by recycling plastic. As our biofilm captures microplastics but does not have the capacity to degrade them, we wanted to recover these microplastics once they are attached to the biofilm. We contacted them to find out more about their recycling technique, to see if we could integrate their method into our design to recycle microplastics.
Key points of the interview:
After giving Ms. Levene a brief introduction to our project, we asked about the DePoly company, to find out more about the methods and techniques they use to recycle plastic. She explained the process that PET waste goes through in order to be recycled. We then asked her whether their technique would also be effective for recycling microplastics, or whether their very small size would be a problem. She explained that microplastics could be recycled, but that their technique would only be effective for PET and that other types of polymer would be rejected as waste. It would therefore be possible for us to send them the different types of microplastics captured by the biofilm, and they could then recover only the PET polymers. Finally, we mentioned our idea of implementing our engineered biofilm in washing machine filters. Our interviewee confirmed that this could be an interesting strategy, as it would make it possible to capture a majority of textile fibers, many of which are PET, which could then be recycled using their method. → see implementation, interconnection with other projects
Learn and re-design
These interviews gave us valuable advice on how to carry out our project, but also led us to question our initial approach. Thanks to these discussions, we reshaped several aspects of our proposal, and gave it a new direction, so that it could be more effective and suitable for solving real-world issues.
1. Peptides binding to specific types of plastic
Our initial plan was to induce overexpression of the Curli fiber in a strain of E. coli
to overproduce biofilm. Leveraging the natural adhesive properties of this natural biomaterial,
we aimed to bind all types of microplastics.
However, Prof. Bernd Nowack (expert of the environmental hazards of microplastics) pointed out the
specificity issue, clarifying that not all types of plastics are equally represented, so binding
specific types of plastics might be more interesting. He advised us to focus mainly on two types
of plastic, polypropylene (PP) and polyethylene (PE), as these are the two types of plastic most
frequently found in water. We followed his advice and decided to functionalize the Curli fibers
of our biofilm with peptides that bind specifically to these types of plastic.
→ see design and engineering
2. Rubber binding domain
During an interview with Pascal Hagmann, director of the Oceaneye association,
we were surprised to discover another kind of microplastic pollution, caused by tyre particles.
Indeed, when we presented our design and implementation idea, he warned us that applying our
biofilm at the level of wastewater treatment plants (WWTPs) would completely miss one major
source of plastic contamination. He explained to us that a major problem for Lake Geneva is the
discharge of huge quantities of rubber particles due to the abrasion of tyres on the roads, directly into the lake.
The tyre particles carried along with the roadside water are in fact flowing through the grids and drains, without passing through the WWTPs.
When we met with Caroline Villard (director of the Morges wastewater treatment plant ERM) and Denis Hostettler
(head of operation of the WWTP) to propose our idea of implementation of the biofilm in the WWTP, they also confirmed that
road water is treated differently from wastewater, and therefore does not pass through the WWTP. Instead, there is a system
of filters under the grids, but these easily allow the tyre particles to pass through, allowing them to be discharged into the lake.
Following this discussion, we could not ignore this key aspect of microplastic pollution,
thereby we decided to add a new dimension to the project, in order to tackle this specific issue.
Since the idea of improving the biofilm specificity through protein domains with affinity for different
materials was promising, we decided to include in our tool box a component that would specifically capture these tyre particles.
After some bibliographic research, we identified a rubber binding domain from a Candida albicans strain that forms biofilms
on catheters1 (see design & engineering).
The development of this new sub-project required a specific implementation strategy, as its deployment could not happen
at the level of WWTPs, but rather on the roads, under completely different environmental conditions.
Our conversation with Ms. Villard and Mr. Hostettler led us to consider possible implementation
strategies in the filter structures that already exist under the grates and in the drains for road water.
One of them would be the use of a cell-free engineered biofilm, which would avoid the risk of GMO dispersal.
Implementation ideas
Our engineered Escherichia coli biofilm, functionalized to capture microplastics, could be implemented at multiple levels, including wastewater treatment plants, road drains, and washing machine filters (see implementation for more information). The application of our solution would require minimal specialized knowledge in synthetic biology, making it easily accessible and deployable. We would initiate the project’s implementation through collaboration with local authorities, wastewater treatment facilities and community organizations. The proposed end-user spans a broad spectrum, from local communities residing around Lake Geneva to any global community eager to combat microplastics pollution in their vicinity. Our vision extends beyond the initial project implementation; we foresee others leveraging our biofilm technology as a foundational tool to address this pressing issue in diverse geographical contexts.
We interacted with many experts and stakeholders, mainly exponents of the scientific community working on plastic pollution and biofilm applications, but also members of associations whose aim is to take action and raise awareness on the issue, as well as workers potentially involved in the cause and solution of the issue. Throughout the project, we kept in mind some key values: a profound respect for the environment, a desire to ensure broad accessibility to our solution, and the continuous interaction with experts to ensure the relevance and appropriateness of our project to be applied in the real world. Moreover, our project aligns with four of the United Nations Sustainable Development Goals, including Good Health and Well-being, Clean Water and Sanitation, Responsible Consumption and Production, and Life Below Water. This highlights the responsible and positive impact our project could have, contributing towards a cleaner, healthier, and more sustainable future for all.