Live cyanobacteria produce photocurrent and hydrogen using both the respiratory and photosynthetic systems

Saper, G. and Kallmann, D. and Conzuelo, F. and Zhao, F. and Tóth, T.N. and Liveanu, V. and Meir, S. and Szymanski, J. and Aharoni, A. and Schuhmann, W. and Rothschild, A. and Schuster, G. and Adir, N.

Volume: 9 Pages:
DOI: 10.1038/s41467-018-04613-x
Published: 2018

Oxygenic photosynthetic organisms perform solar energy conversion of water and CO2 to O2 and sugar at a broad range of wavelengths and light intensities. These cells also metabolize sugars using a respiratory system that functionally overlaps the photosynthetic apparatus. In this study, we describe the harvesting of photocurrent used for hydrogen production from live cyanobacteria. A non-harmful gentle physical treatment of the cyanobacterial cells enables light-driven electron transfer by an endogenous mediator to a graphite electrode in a bio-photoelectrochemical cell, without the addition of sacrificial electron donors or acceptors. We show that the photocurrent is derived from photosystem I and that the electrons originate from carbohydrates digested by the respiratory system. Finally, the current is utilized for hydrogen evolution on the cathode at a bias of 0.65 V. Taken together, we present a bio-photoelectrochemical system where live cyanobacteria produce stable photocurrent that can generate hydrogen. © 2018 The Author(s).

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