Mechanisms of enhanced cellulosic bioethanol fermentation by co-cultivation of Clostridium and Thermoanaerobacter spp.

► We investigated co-cultivation of cellulolytic and non-cellulolytic partner strains. ► Co-cultivation significantly improved ethanol production from cellulose fermentation. ► One partner strain, X514, was superior in enhancing ethanol fermentation. ► Vitamin B12 synthesis was an important determinant of ethanol production efficiency.