Extracellular electron transfer of Pseudomonas stutzeri driven by lithotrophic and mixotrophic denitrification

Abstract

The present study investigated extracellular electron transfer (EET) of Pseudomonas stutzeri, a model organism for bacterial denitrification. Electrochemical cultivation of P. stutzeri in a lithotrophic medium with Fe2+ ions generated the clear cathodic current associated with denitrification reactions. The EET ability of P. stutzeri was greatly strengthened by the addition of acetate, which correlated with the enhanced rate of the enzymatic oxidation of Fe2+. Since the addition of acetate induced the change of cellular metabolisms from lithotrophic denitrification to mixotrophic one, the present finding suggests the effectiveness of EET monitoring as a descriptor of bacterial denitrification activity and changing metabolisms according to the environmental conditions.