mentioned method. However, necessary engineering is necessary in order to obtain
envisioned applications. This will most likely not only include electron delivering
systems but also require genetic engineering of the microorganisms to raise
demanded reactions.
2.5.2 Mediated Electron Transfer (MET)
Some recognized microorganisms have the ability of using soluble components
which physically vehicle produced electrons from an intracellular compound to
anode electrode surface (Rabaey and Verstraete 2005). For example, some redox
materials such as neutral red (Park et al. 1999), thionin (Lithgow et al. 1986), and
methyl viologen (Roller et al. 1984) have been used as electron shuttle previously.
On the other hand, there are some microorganisms producing redox mediators by
themselves, which occurs in two categories: through the organic production and
through oxidizable metabolite generation (Rabaey and Verstraete 2005). Also, some
bacteria such as E. coli, Pseudomonas, Proteus, S. cerevisiae, and species of Bacillus
are not able to transport the produced electron to the surface of anode electrode. As a
result, mediators are the essential parts of MFCs. Besides, there are two types of
mediators known as self-generated mediators and artificial electron mediators
(Rahimnejad and Najafpour 2018). Furthermore, mediators such as pyocyanin and
relevant compound produced by especial types of bacteria have been used to
transport the electrons to the anode surface. It’s worth noting that sometimes the
electrons themselves play the role as mediators and transfer the electrons to the
anode surface.
2.6 Performance of MFC
Some specific important parameters such as rate of substrate conversion,
overpotential, the performance of PEM, and R in in MFCs tremendously affect their
performance (Rabaey and Verstraete 2005). To be added here, various parameters
such as the mixing and mass transfer phenomena in the reactor and the bacterial
kinetics (μ max , the maximum specific growth rate of the bacteria, and Ks, the
bacterial affinity constant which is related to substrate) are directly relevant to
substrate conversion rate in MFCs. Moreover, MFCs’ performance can be
influenced by the electrochemical characteristics of the electrode, the electrode
potential, and the kinetics together with the mechanism of the electron transfer and
MFCs’ current (Jang et al. 2004). Considering the fact R in of MFCs is dependent on
both the resistance of the electrolyte between the electrodes and membrane resistance. Nafion as a PEM has the lowest resistance and is the most chosen one (Deng
et al. 2010).
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M. Rahimnejad et al.
envisioned applications. This will most likely not only include electron delivering
systems but also require genetic engineering of the microorganisms to raise
demanded reactions.
2.5.2 Mediated Electron Transfer (MET)
Some recognized microorganisms have the ability of using soluble components
which physically vehicle produced electrons from an intracellular compound to
anode electrode surface (Rabaey and Verstraete 2005). For example, some redox
materials such as neutral red (Park et al. 1999), thionin (Lithgow et al. 1986), and
methyl viologen (Roller et al. 1984) have been used as electron shuttle previously.
On the other hand, there are some microorganisms producing redox mediators by
themselves, which occurs in two categories: through the organic production and
through oxidizable metabolite generation (Rabaey and Verstraete 2005). Also, some
bacteria such as E. coli, Pseudomonas, Proteus, S. cerevisiae, and species of Bacillus
are not able to transport the produced electron to the surface of anode electrode. As a
result, mediators are the essential parts of MFCs. Besides, there are two types of
mediators known as self-generated mediators and artificial electron mediators
(Rahimnejad and Najafpour 2018). Furthermore, mediators such as pyocyanin and
relevant compound produced by especial types of bacteria have been used to
transport the electrons to the anode surface. It’s worth noting that sometimes the
electrons themselves play the role as mediators and transfer the electrons to the
anode surface.
2.6 Performance of MFC
Some specific important parameters such as rate of substrate conversion,
overpotential, the performance of PEM, and R in in MFCs tremendously affect their
performance (Rabaey and Verstraete 2005). To be added here, various parameters
such as the mixing and mass transfer phenomena in the reactor and the bacterial
kinetics (μ max , the maximum specific growth rate of the bacteria, and Ks, the
bacterial affinity constant which is related to substrate) are directly relevant to
substrate conversion rate in MFCs. Moreover, MFCs’ performance can be
influenced by the electrochemical characteristics of the electrode, the electrode
potential, and the kinetics together with the mechanism of the electron transfer and
MFCs’ current (Jang et al. 2004). Considering the fact R in of MFCs is dependent on
both the resistance of the electrolyte between the electrodes and membrane resistance. Nafion as a PEM has the lowest resistance and is the most chosen one (Deng
et al. 2010).
224
M. Rahimnejad et al.