Hydrogen-producing and electrochemical properties of a dissimilatory Fe(III) reducer Clostridium bifermentans EZ-1

Abstract:

[Objective] To obtain and characterize a versatile strain isolated from the soil of Yellow River Delta. [Methods] The strain was isolated by anaerobic technologies and identified by sequencing the 16S rRNA gene. The morphology was depicted with Gram staining and scanning electron microscope. High performance liquid chromatography and gas chromatography were used to analyze the metabolic substrates and productions. Ferric citrate (FeC₆H₅O₇), ferrihydrite (FeOOH) and magnetite (Fe₃O₄) were supplied to detect the capability of Fe(Ⅲ) reduction of this strain. Microbial fuel cells were constructed with graphite as electrodes to test the electrochemical activity of this strain. [Results] Compared to Clostridium bifermentans, the similarity of 16S rRNA gene is 97.99%. It is a rod, Gram-positive bacterium, which can use glucose to produce hydrogen, carbon dioxide, acetate and butyrate. The Fe(Ⅲ) reduction results showed that it could reduce soluble ferric citrate, amorphous ferrihydrite and crystal magnetite. Furthermore, the electrochemical activity was detected and the maximum current density peaked at 6.5 mA/m². [Conclusion] In this work, a versatile strain which is capable of producing hydrogen, electricity and reducing iron oxide, was successfully isolated from the soil of Yellow River Delta named as Clostridium bifermentans EZ-1.

Key words:coastal wetland;Clostridium bifermentans;producing electricity;hydrogen evolution;dissimilatory Fe(Ⅲ)-reduction