New Mobilizable Vectors Suitable for Gene Replacement in Gram-Negative Bacteria and Their Use in Mapping of the 3′ End of the Xanthomonas campestris pv. campestris gum Operon

We describe useful vectors to select double-crossover events directly in site-directed marker exchange mutagenesis in gram-negative bacteria. These vectors contain the gusA marker gene, providing colorimetric screens to identify bacteria harboring those sequences. The applicability of these vectors was shown by mapping the 3′ end of the Xanthomonas campestris gum operon, involved in biosynthesis of xanthan.

本研究报道了可在革兰氏阴性菌（gram-negative bacteria）的定点标记交换诱变（site-directed marker exchange mutagenesis）中直接筛选双交换事件（double-crossover events）的实用载体。此类载体携带gusA标记基因（gusA marker gene），可通过比色筛选鉴定携带目标序列的细菌。通过对参与黄原胶（xanthan）生物合成（biosynthesis）的野油菜黄单胞菌（Xanthomonas campestris）gum操纵子（gum operon）的3'端进行定位分析，验证了此类载体的适用性。