08.10.2013 09:42 Age: 5 yrs

Wastewater treatment with the PhyscoFilter: Smart moss cleans water

Access to clean water is a basic human right – but one still denied to around 780 million people worldwide. As the pace of industrialization rapidly advances in emerging economies, drinking water is being increasingly contaminated by untreated wastewater. And even water treatment plants do not filter out all impurities, which may include pesticides, medication and hormones. Young researchers at Technische Universität München (TUM) are now applying themselves to these “murky waters”. They want to genetically modify a commonly found type of moss – and turn it into a cost-effective mini water purifier for pharmaceutical agents and chemicals.

Ingmar Polte, Katrin Fischer and Dong-Jiunn Jeffery Truong (from left to right) examining moss growth in the lab. (Photo: Andreas Heddergott / TUM)

The moss Physcomitrella patens on a wire rack. (Photo: Andreas Heddergott / TUM)

Johanna Brüggenthies and Andreas-David Brunner performing the technical test run of their prototype of a floating "moss wastewater treatment plant" in the Freising river Moosach. (Photo: Andreas Heddergott / TUM)

The TUM students in question have entered this moss project in the 2013 international iGEM competition for Synthetic Biology (http://igem.org/About), which will be held at Massachusetts Institute of Technology (MIT) for the ninth time. The aim of the competition is to genetically modify organisms and create capabilities that add value to society.

How can we break down and filter out chemicals for clean water?

The iGEM team is testing two ways of using moss to remove impurities from the water: “Firstly, we want to get the moss to turn hazardous materials into harmless substances (through biodegradation); secondly, it should bind non-biodegradable substances and thus work as a filter (bioaccumulation),” explains Katrin Fischer, a third-year biochemistry student.

For both of these procedures, the young researchers designed and introduced DNA building blocks into the genetic material of the moss. These encode the information for proteins that break down chemicals or bind the contaminants. This allows the moss to break down commonly found substances such as macrolide antibiotics and hormones from the contraceptive pill. The moss also absorbs the insecticide DDT. These types of substance cannot be adequately degraded in conventional water treatment plants.

Genetic switch protects surrounding ecosystems

“The Physcomitrella patens moss is an important water filter in nature – making it the ideal organism for our project,” says Fischer. Although the aim of the students’ project is only to show that moss can work as a filter, they are also looking into potential practical applications.

The students have also found an equally simple but effective solution to ensure that the modified moss does not contaminate surrounding ecosystems: They are using moss with a mutation that ensures it cannot produce mature spores and have also built a self-destruct mechanism into the plant.

“This biological switch is sensitive to light in the red wavelength range,” explains Jeffery Truong, a graduate student of molecular biotechnology and developer of the filter. “To grow the plant, you could use a light filter that specifically removes red light. If the plant accidentally migrates to surrounding areas, it will be exposed to sunlight, which contains light of all wavelengths – so it cannot survive.”

Spotlight on synthetic biology

However, the technical and scientific feasibility focus is only one part of the iGEM project. The students also want to inform the public about the moss filter and use this project to shine the spotlight on the controversial topic of genetic engineering. They have planned various activities in order to do this, including a stand at the Munich Science Days (Münchner Wissenschaftstage) event (http://www.muenchner-wissenschaftstage.de/) in November 2013, as well as events involving school students.

The team is also testing whether the PhyscoFilter can be used in industrial wastewater treatment, and have already developed a prototype for this. Additionally, they will conduct a feasibility study to explore the entrepreneurial potential of this promising idea.

Eyes on the prize

The TUM students are hoping that their PhyscoFilter will earn them a place in the iGEM final, which will be held in Boston on November 1-3, 2013. In total, 223 teams from around the world are participating this year. However, the team first has another hurdle to leap – the European qualifying round in Lyon from October 11-13, 2013.

The 2013 TUM iGEM team has 11 members, most of whom are studying biochemistry or molecular biotechnology, with mathematics and mechanical engineering students providing reinforcement. The young researchers believe that their chances are good, as their project reaches far beyond the technical challenges of genetic engineering, as Truong explains:

“Water is the source of life. But the increasing use of chemicals threatens biodiversity and many ecosystems. With our project, we want to contribute to protecting this valuable resource.”

 

Overview: What can the PhyscoFilter do?

Biodegradation:

1. Degradation of macrolide antibiotics (e.g. erythromycin) by erythromycin esterase B
2. Degradation of polycyclic hydrocarbons (e.g. hormones from the contraceptive pill, which harm aquatic ecosystems)
3. Degradation of catechol (toxic breakdown product of polychlorinated biphenyls (PCBs) by catechol 2.3-dioxygenase)

Bioaccumulation:

1. Absorption of microcystin (cyanobacterial toxin) by protein phosphatase 1
2. Intracellular absorption of DDT (endocrine disruptor pesticide) by glutathione S-transferase
3. Tests using anticalins developed by the Chair of Biological Chemistry (Prof. Dr. Arne Skerra) as potential binding molecules for contaminants in water


For more information see:
iGEM team website

High resolution pictures:
download free of charge for reporting about TUM

Contact:
Prof. Dr. Arne Skerra
Technische Universität München
Chair of Biological Chemistry
T: +49.8161.71-4351
E: skerra[at]tum.de
W: http://www.wzw.tum.de/bc