Wastewater micropollutants, such as pharmaceuticals, are toxic to the environment. Especially animals and plants are affected by these components. Even after purification in wastewater treatment plants, the concentrations of these harmful substances are high enough to cause damage. This also has an impact on the viability and health of the microorganisms in the sewage sludge and thus bares economic consequences in addition to the environmental damage.
With our project, we want to address this problem. For this purpose, we are developing a biofilm-containing Bacillus subtilis that degrades the pollutants. To make this possible, we clone the genes encoding the required enzymes into our bacterium. Due to the variety of enzymes we produce, a wide range of substances can be converted into less toxic molecules, so that our system could be used in many places around the world. Our biofilm is supposed to be implemented in wastewater treatment plants and thus lower the environmental damage.
Why do we want to develop a biofilm-forming bacterial strain and do not use genetically modified bacteria that live as individual cells?
While the wastewater micropollutants are harmful to free-living microbes, bacteria in a biofilm community are more tolerant of them and robust. In addition, the biofilm ensures the supply of oxygen and nutrients to the bacteria1 and, due to the high density of extracellular matrix proteins, enables the accumulation and degradation of a wide range of biomolecules2. The high durability of the biofilm also facilitates its use in wastewater treatment plants. The strong bonds of proteins in the extracellular matrix of the biofilm allow the bacteria to adhere better to so-called carriers for suspended beds, on which they can survive longer in the harsh conditions of the wastewater treatment plants and break down the pollutants more effectively.
Our aim is to reduce the concentration and toxicity of contaminants in water in order to protect the environment and contribute to the fight against pollution.
 “Material properties of biofilms – a review of methods for understanding permeability and mechanics”, Billings et al., 2015
 “Biofilms: an emergent form of bacterial life”, Flemming et al., 2016