Abstract: Three glucose transporters and two membrane\|bound glucose dehydrogenases were knocked out in the phytopathogenic bacterium Xanthomonas campestris pv. campestris 8004. The five mutants and Xcc8004 had little difference in their basic metabolisms， such as cell growth curve， extra\|cellular polysaccharide production and cellulases activities when cultured in nutrition\|rich medium. However， the deletion of sodium/glucose transporter gene （XC_2460） influenced the cell growth when glucose was used as carbon source，but its extra\|cellular glucose yield in carboxymethyl cellulose degradation test was about 167\|fold higher than those of other strains. These results demonstrated the hypothesis that the extracellular glucose concentration from cellulose could be increased significantly by block of glucose influx transport system without affecting basic cell metabolism is feasible.

Key words: Xanthomonas campestris pv. campestris, glucose transporter, gene deletion, function analysis