Part:BBa_K1172203

GldA - glycerol dehydrogenase from Escherichia coli with P T7 and RBS

Usage and Biology

Mediators are essential for the use of Escherichia coli in Microbial Fuel Cells. The main goal when improving MFCs is to enhance the kinetics of the electron transfer between the bacterial cells and the fuel cell anode. Increasing the mediator concentration in the MFC is an efficient way to enhance electron transfer. In order to avoid the usage of expensive and toxic synthetic mediators, we engineered an E. coli KRX strain with an overexpressed glycerol dehydrogenase (GldA). GldA produces the endogenous mediator NADH from NAD⁺ and glycerol, which is the main carbon source in our medium. We were able to produce high amounts of NADH with the optimized E.coli, which resulted in a more efficient electron transfer. This demonstrates that genetically introducing an appropriate oxidoreductase into E. coli via gene manipulation can greatly improve the mediator production and power generation. We could show that the increased intracellular- and extracellular NADH concentration, leads to an enhanced current production in our Microbial Fuel Cell. The overexpression of the glycerol dehydrogenase in Escherichia coli is a great genetic optimization for electron shuttle-mediated extracellular electron transfer from bacteria to electrodes.

Figure 1: Redox reaction catalyzed by the glycerol dehydrogenase: NAD⁺ is reduced to NADH by addition of two electrons (e^-) and one proton (H⁺).

Parts uses

The gldA gene from Escherichia coli was cloned and overexpressed in E. coli KRX under the control of T7 promoter. Besides several other promoters (Table 1) were combined with the coding part gldA in order to characterize the expression of glycerol dehydrogenase GldA.

Table 1: Overview of gldA devices. Combination of gldA coding BioBrick (BBa_K1172201) with different promoters and RBS. The characterization of this BioBrick was performed by comparing Escherichia coli KRX wild type with Escherichia coli KRX carrying BBa_K1172203, BBa_K1172204 and BBa_K1172205.

Sequence and Features

Assembly Compatibility:

• 10
  COMPATIBLE WITH RFC[10]
• 12
  COMPATIBLE WITH RFC[12]
• 21
  COMPATIBLE WITH RFC[21]
• 23
  COMPATIBLE WITH RFC[23]
• 25
  COMPATIBLE WITH RFC[25]
• 1000
  COMPATIBLE WITH RFC[1000]

Results

This part was used to characterize the glycerol dehydrogenase GldA (BBa_K1172201). Please look at the Parts Registry page for BBa_K1172201 for results and detailed information.