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

Nat Commun. 2018 Jun 4;9(1):2168. doi: 10.1038/s41467-018-04613-x.

Abstract

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.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Bacterial Proteins / metabolism
  • Cyanobacteria / metabolism*
  • Cyanobacteria / ultrastructure
  • Electron Transport / radiation effects
  • Hydrogen / metabolism*
  • Light*
  • Microscopy, Electron, Scanning
  • Oxygen Consumption / radiation effects*
  • Photosynthesis / radiation effects*
  • Photosystem I Protein Complex / metabolism
  • Synechocystis / metabolism
  • Synechocystis / ultrastructure

Substances

  • Bacterial Proteins
  • Photosystem I Protein Complex
  • Hydrogen