Team:Stuttgart/Human Practices

Human Practise

Prof. Dr. Karl-Heinrich Engesser is the head of the department for “biological waste air purification” at the institute for Sanitary Engineering, Water Quality and Solid Wastemanagement. Gladly he was willing to discuss this years’ iGEM project with us.

Challenges for the project

We asked him for the biggest challenges he was seeing for the application of our system in a wastewater facility. He was primarily concerned with the stability of the enzymes since they have to withstand degradation by microorganisms as well as the alkaline environment in the wastewater plant. Furthermore, he was concerned about the loss of the enzymes cofactor and the resulting inactivation. He therefore saw great importance in a simple and fast regeneration of the foam and the subsequent reloading with enzymes. Another concern of him was the degradation products after the laccase treatment. He suggested to do a toxicity evaluation of the resulting degradation products to ensure that they are non-toxic. Furthermore, the affinity of the laccases to the targets must be particularly high since the concentration of the substrates in the environment are rather low. Lastly we were discussing the up-scalability of the system since purification of the enzymes is rather expensive and high flow rates could be an issue as well.

Common practise for removal of micropollutants

Moreover he told us that the current common practice for the removal of micropollutants besides UV irradiation and ozonization is the usage and regeneration of activated charcoal. Whereas UV irradiation as well as ozonization are having difficulties removing micro pollutants in really low concentrations. For further information on the activated charcoal usage he recommended to talk to Dr.- Ing. Marie Launay the head of the centre of excellence for trace analysts.

Opinion on the project

Despite the potential difficulties that Prof. Engesser was seeing he was greatly enthusiastic about our project and was really curious about seeing us progressing. We are grateful for the time Prof. Engesser took to discuss with us and for all his input especially about the real life implementation of our project.

Pudium discussion

To connect our research with public interest, we initiated a digital discussion in collaboration with the iGEM-team from the University of Kaiserslautern. With this discussion and the live stream on Twitch, we wanted to raise awareness of the benefits that synthetic biology could bring to wastewater treatment and the environment in general. We also want to strengthen the internal iGEM community by working together with other teams and making this important discussion accessible to everyone. To make our panel discussion beneficial for the audience, the team and our discussion partners, an expert in environmental science was invited. This event was moderated together with a member of the iGEM-team of the TU Kaiserslautern with the aim to present interesting topics and to guide the discussion. Due to Corona, the panel discussion had to be held online to prevent a new chain of infection.

Christian Kaiser, an author of the initiative for a progressive turnaround in agricultural science and expert in the field of environmental science was so kind to discuss our topics with us. Sebastian Brockmann from the iGEM-team Stuttgart and Linda Müller from the iGEM-team Kaiserslautern talked to him about the topics “Influence of human-made water pollution on aquatic ecosystems” and “GMOs to save the environment”. In the first part of our discussion we talked about the environmental impact, agriculture and pharmaceuticals have on water pollution and what could be done better in the future. In the second part of our discussion we talked about advantages and disadvantages of GMOs. More precisely about golden rice, glyphosate resistant plants and counterarguments by Greenpeace and other reputable environment organizations. Thanks to Mr. Kaiser we learned a lot about the different perspectives and insights on the problem of water pollution and the legal situation of GMOs in Europe and especially in Germany.

With this discussion we succeeded in raising public awareness of water pollution and GMOs. Making important topics known is afterall an important step in changing the future to the positive.

Integrated Human Practise

The person

Dr. rer. nat. Bertram Kuch is the head of the department "Hydrobiologie und Organische Spurenanalytik" at the Institute for Sanitary Engineering, Water Quality and Waste Management (ISWA) at the University of Stuttgart. He agreed to attend a meeting to answer some questions regarding the work of his institute as well as the substrates selected by us and their detection methods.

Substrates

Since Mr. Kuch is an expert in trace analysis, the primary goal of the meeting was to gain more knowledge about the selected substrates (diclofenac, carbamazepine, estradiol and tetracycline) and their detection.

First, he recommended concentrating on one of the four selected substances. He suggested Diclofenac, as it is easy to detect by HPLC-MS and it is also the easiest to handle. The precise detection of the remaining three substrates will require modern LC-MS and complex preparation steps. This is why he advised us to first focus our experiments and analysis on diclofenac and only then start testing the remaining substrates.

Work of the ISWA

Mr. Kuch also explained to us that the ISWA, in cooperation with the Büsnau sewage treatment plant, primarily examines water samples on request of third parties (primarily companies) and uses toxicity models to evaluate the effects of the detected substances on the environment and certain "target organisms". He explained that the commercial aspect is primarily decisive for the currently investigated substances in water samples, since mostly companies commission the institute and are therefore only interested in certain substances in this context. Other substances, such as benzotriazoles (contained in corrosion inhibitors) or Autan (contained in anti-mosquito sprays) have been proven to be extremely harmful to the environment (benzotriazoles complex calcium and magnesium, Autan also effects water insects). Nevertheless, they are not investigated in detail due to their broad commercial use.

Toxicity modelling

With regard to the toxicity modelling mentioned above, Mr. Kuch explained that in order to estimate the effects of the detected substances on the environment and selected "target organisms", not necessarily the concentrations of the individual substances are decisive, but rather their chemical-physical properties, bioaccumulation and the behaviour of the detected substances in water (are they e. g. sorbing and stick to surfaces).

Since our plan is to use Lac-Man to break down diclofenac and other drugs and hormones in order to render them harmless, we have to make sure that the resulting cleavage products aren’t even more harmful to the environment. However, little is known about the cleavage products and their harmfulness. As the ISWA is also often analysing Diclofenac and the other substrates as well as some of their cleavage products, Mr. Kuch has kindly offered his help in the assignment of the fission products as well as their toxicity modeling. In this way we hope to be able to show that the laccase cleavage actually results in improvement of water quality and less toxicity.

Opinion on the project

Mr. Kuch showed great enthusiasm for our project and for the idea we are pursuing. Apart from the many ways in which he helped us with structuring our project, he also pointed out some potential problems. From earlier approaches where whole fungi instead of purified laccases were used to purify wastewater, a few problems occurred regarding the real applicability of our project. On the one hand, enormous quantities of water must be filtered, resulting in very high flow rates. Since most of the substances we selected are only present in very low concentrations (0.3-1 µg/l), the conversion rates were also very low. In addition, the fungi cleaved all sorts of substances present in the water, not only the harmful drug residues, which resulted in a large number of even more harmful cleavage products. Nevertheless, Mr. Kuch encouraged us to continue our project as water pollution is nowadays a major problem and projects like ours are essential to help solve this problem.

© Christopher Adelmann, Fabian Klötzer, Jan Schlegel for iGEM Team Stuttgart 2020