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Synergistic microbial consortium for bioenergy generation from complex natural energy sources.

Wang VB, Yam JK, Chua SL, Zhang Q, Cao B, Chye JL, Yang L - ScientificWorldJournal (2014)

Bottom Line: The monospecies S. oneidensis system was able to generate bioenergy in a short experimental time frame while the monospecies E. coli system generated significantly less bioenergy.The synergistic effect is suggested to arise from E. coli and S. oneidensis utilizing different nutrients as electron donors and effect of flavins secreted by S. oneidensis.Confocal images confirmed the presence of biofilms and point towards their importance in generating bioenergy in MFCs.

View Article: PubMed Central - PubMed

Affiliation: Singapore Centre on Environmental Life Sciences Engineering (SCELSE), Nanyang Technological University, Singapore 637551 ; School of Materials Science and Engineering, Nanyang Technological University, Singapore 639798.

ABSTRACT
Microbial species have evolved diverse mechanisms for utilization of complex carbon sources. Proper combination of targeted species can affect bioenergy production from natural waste products. Here, we established a stable microbial consortium with Escherichia coli and Shewanella oneidensis in microbial fuel cells (MFCs) to produce bioenergy from an abundant natural energy source, in the form of the sarcocarp harvested from coconuts. This component is mostly discarded as waste. However, through its usage as a feedstock for MFCs to produce useful energy in this study, the sarcocarp can be utilized meaningfully. The monospecies S. oneidensis system was able to generate bioenergy in a short experimental time frame while the monospecies E. coli system generated significantly less bioenergy. A combination of E. coli and S. oneidensis in the ratio of 1:9 (v:v) significantly enhanced the experimental time frame and magnitude of bioenergy generation. The synergistic effect is suggested to arise from E. coli and S. oneidensis utilizing different nutrients as electron donors and effect of flavins secreted by S. oneidensis. Confocal images confirmed the presence of biofilms and point towards their importance in generating bioenergy in MFCs.

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Related in: MedlinePlus

Average current density versus time of MFCs with various bacterial species and ratios.
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Related In: Results  -  Collection


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fig1: Average current density versus time of MFCs with various bacterial species and ratios.

Mentions: Dual-chamber MFCs were employed to investigate the bioenergy generated as the coconut sarcocarp is broken down through microbial oxidation by the respective bacterial species. The average current densities generated over 72 h were recorded (Figure 1). The consistently low current densities from all operated MFCs were attributed to high internal resistances within the bioelectrochemical devices, which impede charge movement. Further, the media in the anode and cathode chambers contained the sarcocarp slurry, which has limited conductivity. This can be averted through various forms of optimization, such as adopting different device architectures [14], apparatus components, or electrode engineering [15]. However, the focus of this study was to demonstrate facile bioenergy generation through the use of a natural, abundant, and readily available energy source, coconut sarcocarp, by employing common bacterial species. MFCs inoculated with E. coli generated an average maximum current density of ~0.015 μA/cm2 (Figure 1, black trace), whereas S. oneidensis MFCs generated ~0.05 μA/cm2 (Figure 1, red trace). The rapid decrease in average current density generated by the S. oneidensis MFCs after ~6 h is caused by the depletion of suitable energy sources available for S. oneidensis. This is because the single fed batch MFC system was employed in this study, which is in contrast to a continuous fed system, where the energy source can be renewed through a steady exchange of spent and fresh medium. The average current density generated by the S. oneidensis MFCs stabilized at a significantly lower current density of ~0.005 μA/cm2 up to 72 h. MFCs without any inoculum were also operated and negligible current density was generated (Figure 1, grey trace). This indicates that the observed current densities were driven by the microbial actions of E. coli and S. oneidensis mono- and cocultures on the sarcocarp.


Synergistic microbial consortium for bioenergy generation from complex natural energy sources.

Wang VB, Yam JK, Chua SL, Zhang Q, Cao B, Chye JL, Yang L - ScientificWorldJournal (2014)

Average current density versus time of MFCs with various bacterial species and ratios.
© Copyright Policy - open-access
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC4109225&req=5

fig1: Average current density versus time of MFCs with various bacterial species and ratios.
Mentions: Dual-chamber MFCs were employed to investigate the bioenergy generated as the coconut sarcocarp is broken down through microbial oxidation by the respective bacterial species. The average current densities generated over 72 h were recorded (Figure 1). The consistently low current densities from all operated MFCs were attributed to high internal resistances within the bioelectrochemical devices, which impede charge movement. Further, the media in the anode and cathode chambers contained the sarcocarp slurry, which has limited conductivity. This can be averted through various forms of optimization, such as adopting different device architectures [14], apparatus components, or electrode engineering [15]. However, the focus of this study was to demonstrate facile bioenergy generation through the use of a natural, abundant, and readily available energy source, coconut sarcocarp, by employing common bacterial species. MFCs inoculated with E. coli generated an average maximum current density of ~0.015 μA/cm2 (Figure 1, black trace), whereas S. oneidensis MFCs generated ~0.05 μA/cm2 (Figure 1, red trace). The rapid decrease in average current density generated by the S. oneidensis MFCs after ~6 h is caused by the depletion of suitable energy sources available for S. oneidensis. This is because the single fed batch MFC system was employed in this study, which is in contrast to a continuous fed system, where the energy source can be renewed through a steady exchange of spent and fresh medium. The average current density generated by the S. oneidensis MFCs stabilized at a significantly lower current density of ~0.005 μA/cm2 up to 72 h. MFCs without any inoculum were also operated and negligible current density was generated (Figure 1, grey trace). This indicates that the observed current densities were driven by the microbial actions of E. coli and S. oneidensis mono- and cocultures on the sarcocarp.

Bottom Line: The monospecies S. oneidensis system was able to generate bioenergy in a short experimental time frame while the monospecies E. coli system generated significantly less bioenergy.The synergistic effect is suggested to arise from E. coli and S. oneidensis utilizing different nutrients as electron donors and effect of flavins secreted by S. oneidensis.Confocal images confirmed the presence of biofilms and point towards their importance in generating bioenergy in MFCs.

View Article: PubMed Central - PubMed

Affiliation: Singapore Centre on Environmental Life Sciences Engineering (SCELSE), Nanyang Technological University, Singapore 637551 ; School of Materials Science and Engineering, Nanyang Technological University, Singapore 639798.

ABSTRACT
Microbial species have evolved diverse mechanisms for utilization of complex carbon sources. Proper combination of targeted species can affect bioenergy production from natural waste products. Here, we established a stable microbial consortium with Escherichia coli and Shewanella oneidensis in microbial fuel cells (MFCs) to produce bioenergy from an abundant natural energy source, in the form of the sarcocarp harvested from coconuts. This component is mostly discarded as waste. However, through its usage as a feedstock for MFCs to produce useful energy in this study, the sarcocarp can be utilized meaningfully. The monospecies S. oneidensis system was able to generate bioenergy in a short experimental time frame while the monospecies E. coli system generated significantly less bioenergy. A combination of E. coli and S. oneidensis in the ratio of 1:9 (v:v) significantly enhanced the experimental time frame and magnitude of bioenergy generation. The synergistic effect is suggested to arise from E. coli and S. oneidensis utilizing different nutrients as electron donors and effect of flavins secreted by S. oneidensis. Confocal images confirmed the presence of biofilms and point towards their importance in generating bioenergy in MFCs.

Show MeSH
Related in: MedlinePlus