关键词: 伊枯草菌素A；补料；分批发酵；调控基因

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