Researchers developed more efficient strains of Zymomonas mobilis to better use xylose for biofuel production. They combined genetic engineering and lab evolution to create strains that can consume xylose at high levels. By adding specific genes to the strain, they improved its ability to use xylose. The best strain, after 38 transfers in xylose media, showed faster xylose consumption and increased ethanol production compared to the original strain. Genetic analysis revealed key changes in the evolved strain, and gene expression studies showed increased activity in certain genes related to protein folding and cell function in the evolved strain.