The Enzymatic Flagellulose unit will be integrated within the secondary wastewater treatment phase, where biological oxidation takes place. While we intend it to be immobilized it on a rotor inside the tanks, another idea might be to use beads and have them flow through the sewage water in the tank. For this decision to be made, we would have to test what geometry has higher efficiencies regarding the degradation of microplastics. That way, the release of microplastics into the environment, its distribution, and related environmental consequences can be prevented. Furthermore, our functionalized matrix can be expanded to other environmental problematic issues, such as removing medicine residues or pesticides from wastewater. Also, after having developed this modular machine, it could be applied directly where wastewater enters the system – meaning in the drain of a home or an industrial facility. For example, we could use it like a sink strainer by making the Enzymatic Flagellulose home compatible. The main reason we began with applying our Enzymatic Flagellulose in the wastewater treatment plants is that the enzymes need some time to carry out the reactions. While there is not enough time if the water just flows through the sink, in the treatment plants it will stay for several hours in one tank (see below). Later, when we have optimized the enzymes to carry out very fast reactions, the implementation of a microplastics degrading sink strainer is the next application of choice. Thus, our modular machine offers a wide range of application possibilities. By varying and combining the interlinked enzymes of different functions, it can be applied diversely and simultaneously for various purposes.

4.1 Collaboration TU Delft

Essay of how to integrate the project of iGEM Berlin and iGEM Delft

The iGEM team of Berlin uses synthetic biology to develop a molecular filtering machine. This project has great opportunities in solving the problems with microplastics finding their ways into the wastewater treatment plant. During the wastewater treatment, the microplastics are not removed sufficiently. The ‘escaped’ microplastics are taken up by organisms living in rivers, lakes and the oceans, but also by human beings through the food chain. To date, no scalable approaches has been found to solve this problem.

Luckily, the iGEM team of Berlin has the solution for the problem with microplastics; a molecular filtering machine. Their proposed filter consists of a surface made up of cellulose to which bacterial flagella will be immobilized. The attachment required for this will be achieved via a cellulose binding domain. The single flagella-subunits, also known as flagellin, will be interlinked with plastic-degrading enzymes. Thus, this system enables an increased specific surface with highly catalytic activity.

Not only Berlin see the opportunities of this project, also the iGEM team of the TU Delft. This teams is working with E. coli bacteria that can form nanowires at an induced moment. These nanowires will link the bacteria to each other provide a stable structure. With a 3D printer, layers of bacteria can be formed in a predesigned way. Another advantage of this technique is that the enzymes produced by the bacteria can covalent bind to the nanowires (Botyanszki, Tay et al. 2015). In this case, the scaffold of cellulose is not required anymore. [MP1] Moreover, the printer and nanowires generate a highly flexible machine, since every cell type and every enzyme could potentially be produced. One of the requirements posed by Berlin’s team is that the filter is highly flexible in use, so that it can be used for different types of water. So, by combining these technologies, the filtering machine proposed by Berlin’s iGEM team becomes even more attractive.

Reference:
Botyanszki, Z., P. K. Tay, P. Q. Nguyen, M. G. Nussbaumer and N. S. Joshi (2015). "Engineered catalytic biofilms: Site-specific enzyme immobilization onto E. coli curli nanofibers." Biotechnol Bioeng 112(10): 2016-2024.