Syntrophic interactions drive the hydrogen production from glucose at low temperature in microbial electrolysis cells

► H2 production from glucose at 4 °C in MECs overcomes the dark-fermentation bottleneck. ► H2 yield at 4 °C is comparable with that obtained at mesophilic temperatures in MECs. ► Combining pyrosequencing with CV reveal the syntrophic interactions in MECs at 4 °C. ► Psychrotolerant fermenters and exoelectrogens allowed current generation from glucose. ► Methanogenesis and homoacetogenesis were negligible in glucose-fed MECs at 4 °C.