Fe(II)EDTA–NO reduction coupled with Fe(II)EDTA oxidation by a nitrate- and Fe(III)-reducing bacterium

The nitrate- and Fe(III)-reducing bacterium Paracoccus versutus LYM was characterized in terms of its ability to perform Fe(II)EDTA–NO reduction coupled with Fe(II)EDTA oxidation (NO-dependent Fe(II)EDTA oxidation, NDFO). It experienced a single anaerobic FeEDTA redox cycling through NDFO and dissimilatory Fe(III)EDTA reduction in FeEDTA culture. The increase in the Fe(II)EDTA concentration contributed to the ascending Fe(II)EDTA–NO reduction rate. The amount of glucose controlled the rate and extent of Fe(II) oxidation during NDFO. Without glucose addition, Fe(II)EDTA–NO reduction rate was at a rather slow rate even in presence of relatively sufficient Fe(II)EDTA. Unlike aqueous Fe2+ and solid-phase Fe(II), Fe(II)EDTA could prevent cells from encrustations. These findings suggested the occurrence of NDFO preferred being beneficial via a mixotrophic physiology in the presence of an organic cosubstrate to being out of consideration for metabolic strategy.