<jats:title>Abstract</jats:title><jats:p>Interspecies electron transfer is a common way to couple metabolic energy balances between different species in mixed culture consortia. Direct interspecies electron transfer (DIET) mechanism has been recently characterised with <jats:italic>Geobacter</jats:italic> species which couple the electron balance with other species through physical contacts. Using this mechanism could be an efficient and cost-effective way to directly control redox balances in co-culture fermentation. The present study deals with a co-culture of <jats:italic>Geobacter sulfurreducens</jats:italic> and <jats:italic>Clostridium pasteurianum</jats:italic> during glycerol fermentation. As a result, it was shown that <jats:italic>Geobacter sulfurreducens</jats:italic> was able to grow using <jats:italic>Clostridium pasteurianum</jats:italic> as sole electron acceptor. <jats:italic>C. pasteurianum</jats:italic> metabolic pattern was significantly altered towards improved 1,3-propanediol and butyrate production (+37% and +38% resp.) at the expense of butanol and ethanol production (−16% and −20% resp.). This metabolic shift was clearly induced by a small electron uptake that represented less than 0.6% of the electrons consumed by <jats:italic>C. pasteurianum</jats:italic>. A non-linear relationship was found between <jats:italic>G. sulfurreducens</jats:italic> growth (<jats:italic>i.e</jats:italic> the electrons transferred between the two species) and the changes in <jats:italic>C. pasteurianum</jats:italic> metabolite distribution. This study opens up new possibilities for controlling and increasing specificity in mixed culture fermentation.