Microbial biofilms are sensitive to the poise potentials in a bioelectrochemical system. So, what is the range within which the bioelectrodes can be poised?
I think it will depend upon the application and whether it is a bioanode or biocathode. For Biocathodes, I have seen them being poised from anywhere between -400 mv to -1.1 V vs Ag/AgCl. See the recent papers on Microbial Electrosynthesis for this.
Recently for a methane-producing microbial electrolysis cell, Aulenta et al., poisd the anode from + 200 mV and − 200 mV vs. SHE. See this paper, http://www.sciencedirect.com/science/article/pii/S156753941530013X.
Earlier in 2008, Peter Alterman tested a MFC anode poised at of 0 (R0), -200 (R(-200)) and -400 (R(-400)) mV versus Ag/AgCl. See this paper, http://www.ncbi.nlm.nih.gov/pubmed/18193419
Finally the max potential is anything that does not kill your biofilm. :)
Thanks Dr. Pant for your answer... Even though there are reports of various voltages being tried for bioanodes and biocathodes, is there a theoretical threshold above or below which we can't go? The voltages we can apply to BES is a major distinguishing factor from abiotic cells, so what are the limits beyond which we should not go... thanks once again :)
Hi Pratiksha,
It will depend for each electroactive bacteria/biofilm. There won't be a generic figure that you will find. Also, after a certain applied potential, there is no further effect on the respective conversion/biomass yield no matter how high/low potential you apply. I remember a paper from Uwe Schroeder about Geobacter where they reported that "Over a range of anode potentials from −0.105 to +0.645 V versus standard hydrogen electrode, G. sulfurreducens produced identical amounts of biomass per electron respired. This indicated that the organism cannot utilize higher available energies for energy conservation to ATP. Either the high potentials cannot be used due to physiological limitations, or G. sulfurreducens decreased its metabolic efficiency, and less biomass per unit of energy was produced. In this case, G. sulfurreducens “wasted” energy at high-potential differences, most likely as heat to fuel growth kinetics." The reference is- Bosch, J., Lee, K., Hong, S. et al. Curr Microbiol (2014) 68: 763. doi:10.1007/s00284-014-0539-2. Hope this helps.
Good luck.
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