Development of Shewanalla Oneidensis MR-1 for Bioelectricity Generation from Glycerol: Induction of Glycerol Uptake Module

Glycerol is a waste byproduct from many biomass conversion processes; however it can be converted to valuable platform chemicals and biomaterials. Microbial fuel cells (MFCs) are the new type of bioprocess which can generate electricity and produce chemicals from biodegradable biomass using electrochemically active microorganism as biocatalyst. In the previous studies, the typical electrochemically active microbe, Shewanella sp. can metabolize lower carbon sources such as lactate and formate, but does not produce electricity from glycerol. In this study, we hypothesized that bioelectricity generation from glycerol could be obtained by introduction of glycerol oxidation modules through expression of the genes such as glpF, glpK, glpD. Voltage productions from lactate were obtained as 70 and 75 mV in MFCs using both wild type S. oneidensis MR-1 and recombinant S. oneidensis MR-1, respectively. In the case of glycerol substrate, significantly higher voltage productions were found in recombinant S. oneidensis MR-1 (80 mV) as compared to the wild-type S. oneidensis MR-1 (< 10 mV). The glycerol uptake activities were investigated by electrochemical analysis through cyclic voltammetry and power density curve. This study shows that recombinant S. oneidensis MR-1 oxidizes glycerol and increase cellular redox state by induction of glycerol metabolism. Using the genetically engineered glycerol metabolism, bioelectrochemical system could provide a platform to product value-added chemicals and bioconversion process in further study.