1. A recombinant bacterial strain selected from the group consisting of Zymomonas and Zymobacter comprising a heterologous nucleic acid molecule encoding a polypeptide having xylose isomerase activity wherein the polypeptide is a Group I xylose isomerase and is included in the class of enzymes identified by EC 5.3.1.5, and wherein the strain utilizes xylose as a carbon source and wherein the heterologous nucleic acid molecule encoding a polypeptide having xylose isomerase activity is not under the control of a promoter derived from Zymomonas mobilis glyceraldehyde-3-phosphate dehydrogenase gene that has a base substitution in a position selected from the group consisting of position 116, position 217, and both position 116 and 217; wherein the position numbers are of SEQ ID NO:311; and wherein the strain demonstrates an increase in xylose utilization of between about 1.9 fold to about 17.1 fold as compared with a strain expressing a Group II xylose isomerase.