Results

MFC

• After extensive optimization, we were able to build a well functioning microbial fuel cell and establish a protocol for measuring the power output of our electricity generating cultures. We built a stack of five fuel cells, which was successfully used to power different LEDs and the motor of a small fan. Furthermore, a 3D model was designed, which can be printed out using a 3D printer. This model was made available for download on our wiki, so anyone interested can build a fuel cell of their own.

Glycerol dehydrogenase

• We demonstrate that engineering E. coli by introduction of appropriate oxidoreductase glycerol dehydrogenase via gene manipulation can greatly improve the mediator production and power generation. We can show an extremely increased intracellular- and extracellular NADH concentration. This leads to 20 % enhanced current production in our Microbial Fuel Cell. The overexpression of Glycerol dehydrogenase from Escherichia coli is a great genetic optimization for electron shuttle-mediated extracellular electron transfer from bacteria to electrodes. Read more about GldA in detail.

Riboflavin

• Riboflavin possesses the ability to be a potent redoxmediator. By turning the rib-gene cluster from Shewanella oneidensis into a BioBrick and subsequently cloning it into the desired chasi Escherichia coli, the iGEM Team Bielefeld was able to raise the amount of riboflavin produced by E. coli significantly.
  This means that the transformation of E. coli with BBa_K1172303, respectively BBa_K1172306, represents a viable option when considering genetical optimization of microorganisms intended for usage in microbial fuel cells (MFC).

Phenazine

• There are no practical results in this section. The project was left aside after unsuccessful attempts to amplify the phenazine-coding fragment from Pseudomonas fluorescens sp.

Porins

• We heterologously expressed the porin protein OprF from Pseudomonas fluorescens into Escherichia coli. This leads to dramatically increased membrane permeability and a much higher current output in comparison to its parental strain (E. coli KRX) caused by improved electron shuttle-mediated extracellular electron transfer. The heterologous expression of outer membrane porin OprF from Pseudomonas fluorescens in Escherichia coli is a great genetic strategy to improve electricity generation by microorganisms. Read more in detail.

Cytochromes

• We isolated the mtrCAB gene cluster from Shewanella oneidensis MR-1 and cloned it into the backbone pSB1C3 generating the BioBrick <bbpart>K1172401</bbpart>. We combined this gene cluster with three promoters of varying strength. We transformed them into our host organism Escherichia coli,, though we could not verify correct expression and localisation. Read more in detail.

Nanowires

• After the successful amplification of the appropriate Geobacter sulfurreducens gene clusters the transformation of these DNA sequences into the BioBrick form via Gibson Assembly lead to substantial problems. Because of additional issues the nanowire project was stopped under further notice to concentrate on the other projects.

Biosafety

• Biosafety is an essential aspect when taking part in iGEM especially when you work with living organisms which could possibly get out of your application by damage or incorrect handling. It is important to protect the population and the environment by developing and applying systems which comply these aspects. Read more on the Biosafety page.