Genetically Engineered Cyanobacteria Enhances Photocurrent Generation in Photo-bioelectrochemical Cell

Photosynthetic energy conversion using natural systems is increasingly being investigated in the recent years. Photosynthetic microorganisms such as cyanobacteria exhibit light dependent electrogenic characteristics in photo bio-electrochemical cells¹ (PBEC) and/or photosynthetic microbial fuel cells² (PMFC) that generate substantial yet lower photocurrents than their photovoltaics counterparts. Recently we demonstrated that a cyanobacterium named Nostoc sp. employed in PBEC could generate up to 35 mW/m² even in a non-engineered PBEC.  With the insights obtained from our previous research², a novel and successful attempt has been made in the current study to genetically engineer the cyanobacteria to further enhance its extracellular electron transfer. The cyanobacterium Synechococcus elongatus PCC7942 was genetically engineered to express a non-native outer membrane redox protein. The engineered S. elongatus exhibited very high extracellular electron transfer ability resulting in ~ 9 fold higher photocurrent generation on the anode of a PBEC than the corresponding wild-type cyanobacterium. This work highlights the scope for enhancing photocurrent generation in cyanobacteria thereby benefiting faster advancement of the PMFC technology.

References

1. J. M. Pisciotta, Y. Zou and I. V. Baskakov, PLoS One, 2010, 5, 10
2. N. Sekar, Y. Umasankar, R. Ramasamy Phys.Chem.Chem.Phys., 2014,16,7862