Theoretical exploration of optimal metabolic flux distributions for extracellular electron transfer by Shewanella oneidensis MR-1

Biotechnology for Biofuels

Longfei Mao¹  Wynand S Verwoerd¹ 

[1] Centre for Advanced Computational Solutions, Department of Molecular Biosciences, Lincoln University, Ellesmere Junction Road/Springs Road, Lincoln 7647, Canterbury Plains, New Zealand

关键词: Microbial metabolism;    FATMIN;    Flux minimization;    Flux variability analysis;    Flux balance analysis;    Bioelectricity;    Shewanella oneidensis MR-1;    Microbial fuel cell;    MFC;   

Others  :  1084661
DOI  :  10.1186/s13068-014-0118-6

 received in 2014-04-16, accepted in 2014-07-25,  发布年份 2014

【 摘 要 】

Background

Shewanella oneidensis MR-1 is one of the model microorganisms used for extracellular electron transfer. In this study, to elucidate the capability and the relevant metabolic processes of S. oneidensis MR-1 involved in an electron transferring environment, we employed genome-scale modelling to model the necessary metabolic states and flux adjustments for electricity generation in the cytochrome c-based direct electron transfer (DET) mode, the NADH-linked mediated electron transfer (MET) mode and a presumable mixed mode comprising DET and flavin secretion. These are difficult to develop experimentally.

Results

The results showed that the microbe had the potential to achieve current outputs of up to 2.610 A/gDW in the DET mode, 2.189 A/gDW in the MET mode and 2.197 A/gDW in the mixed mode. Compared with the DET mode, which relied on cytochrome c oxidase (EC: 1.1.1.2) to mediate the electron transfer, the MET mode was mainly dependent on two routes, catalysed by isocitrate dehydrogenase (NAD) (EC: 1.1.1.4) and NAD transhydrogenase, for the computed high current density value. In the mixed mode, whereas the cytochrome c-based DET accounted for most of the computed maximum current output value, the two flavins combined, riboflavin and FMN, played a much less important role in the probed current value.

Conclusions

Shewanella oneidensis MR-1 has the potential to sustain a high extracellular electron transfer rate similarly to Geobacter sulfurreducens, but relies on different intracellular mechanisms. Various levels of electron transfer rates are achieved by different combinations of metabolic pathways. Flavins can significantly degenerate the maximum electricity generation capability of the cell and the biomass formation, and thus should be avoided in order to achieve a high coulombic efficiency.

【 授权许可】

   
2014 Mao and Verwoerd; licensee BioMed Central Ltd.

【 图 表 】

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