To confer the ability to ferment cello-oligosaccharides on the ethanol-producing bacterium, Zymomonas mobilis, the beta-glucosidase gene from Ruminococcus albus, tagged at its N-terminal with the 53-amino acid Tat signal peptide from the periplasmic enzyme glucose-fructose oxidoreductase from Z. mobilis, was introduced into the strain. The tag enabled 61% of the beta-glucosidase activity to be transported through the cytoplasmic membrane of the recombinant strain which then produced 0.49 g ethanol/g cellobiose.