中文摘要：

野油菜黄单胞菌野油菜致病变种是发酵工业生产黄原胶的菌种，通过对Xcc8004菌株全基因组序列进行搜索，发现该菌株拥有完整的ED、EMP、HMP等糖代谢途径。为评估ED途径对细胞功能的影响，选择基因组中编码ED途径的关键酶——2-酮-3-脱氧-6-磷酸葡萄糖酸醛缩酶的基因eda进行诱变，构建非极性突变体。通过对突变体表型进行分析，发现eda基因的突变体在培养基中能够正常生长繁殖，但其胞外多糖产量则降低77．6％。用一段包含eda基因的DNA片段对突变体进行功能互补，能基本恢复胞外多糖产量。这表明eda基因对细胞合成胞外多糖有重要影响，也暗示ED途径对细胞生长是非必要的，而对细胞大量合成胞外多糖是必须的。

英文摘要：

Xanthomonas campestris pv. campestris （Xcc） is used to produce xanthan gum in ferment industry. A survey of the genome sequence data of Xcc 8004 strain revealed that this bacterium possessed ED, EMP and HMP pathway. To assess the function of ED pathway in Xcc 8004, the eda gene, which encoding 2-keto-3-deoxy-6-phospho-gluconate aldolase, was mutated using the suicide plasmid pK18mob, and resulted nopolar integrated mutant. Phenotype analysis showed that the mutant grown normally in medium, however, the extracellular polysaccharide production reduced 77.6% compared to that of the wild type strain 8004. The eda mutant could be complemented in trans with the intact eda gene, and the EPS production was restored. The results indicated that eda gene is required for EPS production, suggesting ED pathway is essential for EPS production but not cell growth in Xcc.