Lactate Oxidation Coupled to Iron or Electrode Reduction by Geobacter sulfurreducens PCA

Geobacter sulfurreducens PCA completely oxidized lactate and reduced iron or an electrode, producing pyruvate and acetate intermediates. Compared to the current produced by Shewanella oneidensis MR-1, G. sulfurreducens PCA produced 10-times-higher current levels in lactate-fed microbial electrolysis cells. The kinetic and comparative analyses reported here suggest a prominent role of G. sulfurreducens strains in metal-and electrode-reducing communities supplied with lactate. There is great interest in the study of bacteria capable of transferring electrons to solid electron acceptors, such as metal oxides or electrodes, in different types of bioelectrochemical systems (BESs). The two most-studied exoelectrogenic bacte-ria are Geobacter sulfurreducens PCA and Shewanella oneiden-sis MR-1 (1, 2, 9, 23), but these microorganisms have never been studied under exactly the same conditions in BESs. S. oneidensis MR-1 can grow anaerobically using lactate, but it produces acetate, which it cannot further oxidize under these conditions. 16S rRNAs sequences similar to those found wit