野油菜黄单胞菌6-磷酸葡萄糖脱氢酶基因的初步分析

野油菜黄单胞菌野油菜变种是发酵工业生产黄原胶的菌种,对该菌8004菌株全基因组序列进行分析,发现基因组中有两个编码6-磷酸葡萄糖脱氢酶的基因,编号分别为XC1977和XC4082,同源性分析显示这两个基因演绎的氨基酸序列只有36.3%的相似性。为了解这两个基因的功能,采用自杀质粒pK18 mob对XC1977和XC4082分别进行诱变,构建这两个基因的非极性突变体,对突变体表型初步分析,发现XC1977和XC4082分别突变后不影响细胞的生长繁殖,但对胞外多糖产量的影响则不相同,XC1977突变使胞外多糖产量降低56.3%,而XC4082突变基本不影响胞外多糖产量,表明8004菌株的两个zwf基因在细胞中的功能不同,XC1977与细胞的胞外多糖合成产量有关。

Elementary analysis of glucose-6-phosphate dehydrogenase genes of Xanthomonas campestris

Xanthomonas campestris pv.campestris(Xcc) is used to produce xanthan gum in ferment industry.Examination of the complete genome sequence of Xcc 8004 strain revealed that two zwf genes,one was named XC1977,the other was XC4082,which encoding glucose-6-phosphate dehydrogenase,were harbored.Sequence analysis showed that the similarity was only 36.3% between the two genes.The two genes were inactived respectively by using suicided plasmid pK18mob and nopolar integrated mutants were attained.Analysis showed that the extracellular polysaccharide yield of the XC1977 mutant decreased 56.3% compared to that of the wild type strain 8004,while that of the XC4082 mutant was almost the same with that of 8004 strain.The result indicated that the function of the two zwf genes is diverse and XC1977 is involved in extracellular polysaccharide(EPS) biosynthesis.