Extracellular electron transfer of biocathodes: Revealing the potentials for nitrate and nitrite reduction of denitrifying microbiomes dominated by Thiobacillus sp.

From February to May 2014, Narcís Pous carried out a research stay at the laboratory of Dr. Falk Harnisch (UFZ (Leipzig, Germany)). 

This fruitful collaboration has allowed us to publish the article Extracellular electron transfer of biocathodes: Revealing the potentials for nitrate and nitrite reduction of denitrifying microbiomes dominated by Thiobacillus sp.  in the journal Electrochemistry Communications. 

The work has been carried out by Narcis Pous, Christin Koch, Jesús Colprim, Sebastià Puig and Falk Harnisch.

In this article we were able to show the respective reduction potentials for nitrate and nitrite in a Thiobacillus sp. enriched biocathode. This finding will clearly contribute to the engineering (start-up and operation) of denitrifying bioelectrochemical systems.

The abstract is:

"The use of biocathodes in bioelectrochemical systems (BES) for the removal of nitrate

in wastewater has become a vital field of research. However, the elucidation of the

underlying extracellular electron transfer (EET) fundamentals of denitrifying

biocathodes is still lacking, but required for a deeper BES understanding and

engineering. This study reports for the first time on the thermodynamics of microbial

cathodes for nitrate and nitrite reductions using microbial microcosms isolated from a

running denitrifying BES. Cyclic voltammetry showed that nitrate and nitrite reduction

proceed at -0.30V, and -0.70V vs. Ag/AgCl, respectively, by surface associated EET

sites. The biocathodes were predominantly covered by Thiobacillus sp. contributing

with a nitrate reductase (narG) to the major function of the microscosms. In conclusion,

the EET characteristics of denitrifying biocathodes are demonstrated for the first time."

The collaboration with Dr. Harnisch have been a pleasure for us, and we hope to continue collaborating close together!