黄单胞菌葡萄糖转运系统相关基因的敲除及功能分析

分别敲除了植物病原体野油菜黄单胞菌（Xanthomonas campestris pv. campestris 8004）的3个葡萄糖转运蛋白和2个葡萄糖脱氢酶，获得了5株相应基因敲除的突变体。在营养丰富的培养基中，这5株突变体的生长曲线、胞外纤维素酶活性和胞外多糖量与野生型相比并无显著差异。在以葡萄糖为唯一碳源的M63培养基中，XC_2460基因的敲除显著影响了黄单胞菌的生长；在以CMC作为唯一碳源的M63培养基中，XC_2460基因的敲除使突变体的胞外葡萄糖累积量达到野生菌株的167倍。这些结果首次显示阻遏葡萄糖的跨膜转运是改进纤维素分解菌株积累葡萄糖量的有益途径。

Knock out deletion and functional analysis of glucose transportation system in Xanthomonas campestris pv. campestris

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.