Hey everyone,

I am not sure If we have had this area before…Thought it was interesting as it is on bacterial metabolism and how engineer it…

The discussion will be as usual on a Tuesday night at 8 pm BST on twitter. It will be on the 17th of September.

The paper title is:

Electrochemical Gating of Tricarboxylic Acid Cycle in Electricity-Producing Bacterial Cells of Shewanella

and it can be found here:



Energy-conversion systems mediated by bacterial metabolism have recently attracted much attention, and therefore, demands for tuning of bacterial metabolism are increasing. It is widely recognized that intracellular redox atmosphere which is generally tuned by dissolved oxygen concentration or by appropriate selection of an electron acceptor for respiration is one of the important factors determining the bacterial metabolism. In general, electrochemical approaches are valuable for regulation of redox-active objects. However, the intracellular redox conditions are extremely difficult to control electrochemically because of the presence of insulative phospholipid bilayer membranes. In the present work, the limitation can be overcome by use of the bacterial genus Shewanella, which consists of species that are able to respire via cytochromes abundantly expressed in their outer-membrane with solid-state electron acceptors, including anodes. The electrochemical characterization and the gene expression analysis revealed that the activity of tricarboxylic acid (TCA) cycle in Shewanella cells can be reversibly gated simply by changing the anode potential. Importantly, our present results forShewanella cells cultured in an electrochemical system under poised potential conditions showed the opposite relationship between the current and electron acceptor energy level, and indicate that this unique behavior originates from deactivation of the TCA cycle in the (over-)oxidative region. Our result obtained in this study is the first demonstration of the electrochemical gating of TCA cycle of living cells. And we believe that our findings will contribute to a deeper understanding of redox-dependent regulation systems in living cells, in which the intracellular redox atmosphere is a critical factor determining the regulation of various metabolic and genetic processes.

Discussion points:

  1. What did you think of the paper? Nicely written? Easy to understand? Aims of the study?
  2. Did you miss any experiment/controls etc that would have been nice to see?
  3. How could this research be used in future?
  4. Could the outer-membrane cytochromes (OMC) of Shewanella be expressed in other genus of bacteria and which effect would it have?