Abstract:

In order to study the effect of feeding on  Bacillus subtilis ZK8 synthesizing Iturin A, this paper took “nitrogen source + carbon source + amino acid” as supplementary food, applied RT-qPCR technology combined with related fermentation parameters, and analyzed 3 synthesis regulatory genes degQ, degUS, glnR and the relative expression differences of operon itu during fermentation process. The results showed that the total nitrogen and reducing sugar contents in fed-batch fermentation were higher than that in batch fermentation, and the biomass and titer in fed-batch fermentation increased by 68.85% and 36.67%, respectively; the relative expression of the 3 key regulatory genes in  fed-batch fermentation was higher than those in batch fermentation, and the change of 3 genes′ relative expression level was consistent with the synthesis law of Iturin A, as well as the change of operon itus relative expression level. This indicated that supplementary food liquid  could enhance the expression of degQ, degUS and glnR, provide rich carbon source, nitrogen source, and synthesis precursor of Iturin A, and also promote the synthesis of Iturin A.

Key words: Iturin A, feeding, batch fermentation, regulatory gene

摘要：

为研究补料对分批发酵工艺中枯草芽胞杆菌（Bacillus subtilis）ZK8产伊枯草菌素A的影响，以“氮源+碳源+氨基酸”为补料，应用RT-qPCR技术并结合相关发酵参数分析了3个合成调控基因degQ、degUS、glnR及操纵子itu在发酵过程中的相对表达量差异。结果显示：补料-分批发酵工艺中总氮和还原糖的含量高于分批发酵工艺，生物量和效价分别提高了68.85%和36.67%；补料-分批发酵工艺中degQ、degUS和glnR 3个基因的相对表达量均高于分批发酵工艺，3个基因相对表达量的变化规律与伊枯草菌素A合成规律、操纵子itu的相对表达量变化规律一致。表明流加补料液促进了degQ、degUS和glnR的表达，为菌体提供了丰富的碳源、氮源和伊枯草菌素A的合成前体，促进了伊枯草菌素A的合成。

关键词: 伊枯草菌素A；补料；分批发酵；调控基因