枯草芽孢杆菌GMP还原酶基因（guaC）突变株的构建

以受体菌的guaC基因为同源重组的指导序列,构建了整合表达载体pGT9GH,通过双交叉同源重组的方法将线性化的pGT9GH整合到受体菌的染色体上,构建了guaC基因的缺失突变株B.subtilis GJ07,并在guaC基因的5′端和3′端之间引入了一个拷贝核黄素操纵子,通过PCR方法验证了同源重组的正确性,最后测定了同源重组突变后的菌株GJ07的核黄素产量。结果表明：同源重组突变后的菌株GJ07的核黄素产量明显高于初始菌株GJ06,发酵60 h提高了24.5%。

Construction of Bacillus subtilis GMP Reductase Gene (guaC) Mutant

An integrated expression vector pGT9GH by using guaC gene of receptor strain as guide sequence for homologous recombination.And then,by using the method of double crossover recombination between plasmid and chromosome,the linearizated plasmid pGT9GH were integrated into receptor strain to get guaC gene mutant B.subtilis GJ07,in which,one copy of lactochrome operon was inserted between 5′ and 3′ terminal of guaC gene.The homologous recombination events were confirmed by PCR methods,and then,the riboflavin yield of mutant strain GJ07 was measured.The results of shake flask culture showed that,the production of riboflavin of GJ07 was 24.5% higher than that of GJ06 in 60 h.