A Zymomonas mobilis DNA fragment consisting of 207 nucleotides, which corresponded to the 5'-flanking region of an adhB gene encoding alcohol dehydrogenase II, was fused to the structural gene coding for a Bacillus endo-β-1, 4-glucanase. The Z. mobilis DNA fragment was identified to promote 50-fold increase in the expression of endo-β-1,4 glucanase gene in Escherichia coli.