When microorganisms in the MFC system are
capable of completely oxidizing the organic substrate to CO2 higher columbic efficiencies have
been reported. Bacteria reported to be capable of the complete oxidation of an organic substrate in
a MFC system include: Geothrix fermentans (94% columbic efficiency oxidizing acetate) ;
Geobacter species (approaching 100 % columbic efficiency oxidizing acetate or 84% oxidizing
benzoate) ; and Rhodoferax ferrireducens (83% columbic efficiency oxidizing glucose) .
Reported columbic efficiencies can vary greatly when environmental inoculums are used, such as
wastewater, with a maximum of 65–89 % being reported after microbial enrichment .