Enhanced photo-bioelectrochemical energy conversion by genetically engineered cyanobacteria.
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-bioelectrochemical cells (PBEC) that generate substantial photocurrents, yet the current densities are lower than their photovoltaic counterparts. Recently, we demonstrated that a cyanobacterium named Nostoc sp. employed in PBEC could generate up to 35 mW m(-2) even in a non-engineered PBEC. With the insights obtained from our previous research, 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 PCC 7942 was genetically engineered to express a non-native redox protein called outer membrane cytochrome S (OmcS). OmcS is predominantly responsible for metal reducing abilities of exoelectrogens such as Geobacter sp. The engineered S. elongatus exhibited higher extracellular electron transfer ability resulting in approximately ninefold 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 photosynthetic microbial fuel cell technology.
Nano Electrochemistry Laboratory, College of Engineering, University of Georgia, Athens, Georgia, 30602.
Narendran
N
Sekar
Biosynthetic Engineering and Biocatalysis Laboratory, College of Engineering, University of Georgia, Athens, Georgia.
Rachit
R
Jain
Biosynthetic Engineering and Biocatalysis Laboratory, College of Engineering, University of Georgia, Athens, Georgia.
Yajun
Y
Yan
Nano Electrochemistry Laboratory, College of Engineering, University of Georgia, Athens, Georgia, 30602. rama@uga.edu.
Ramaraja P
RP
Ramasamy
D001425:Bacterial Outer Membrane Proteins / Q000235:genetics / Q000378:metabolism; D001674:Bioelectric Energy Sources; D003580:Cytochromes / Q000235:genetics / Q000378:metabolism; D004579:Electron Transport; D015870:Gene Expression; D060847:Metabolic Engineering; D010788:Photosynthesis; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D046940:Synechococcus / Q000235:genetics* / Q000378:metabolism*
D001425:Bacterial Outer Membrane Proteins; D003580:Cytochromes; D011994:Recombinant Proteins
Synechococcus elongatus; extracellular electron transfer; genetic engineering; outer membrane cytochrome; photocurrent; photosynthetic microbial fuel cell