碱性pH冲击对井冈霉素发酵的影响及其机制探讨

发布时间：2018-05-14 10:15

本文选题：吸水链霉菌5008 + 井冈霉素　；参考：《浙江大学》2017年硕士论文

【摘要】：井冈霉素,是农业上应用最广最为有效的抗真菌类抗生素之一,对水稻纹枯病的防治效果极佳。发酵pH是影响井冈霉素发酵过程的一个重要因素,环境压力是促进链霉菌次生代谢产物产生的重要途径,但是有关pH冲击对井冈霉素发酵过程的研究比较有限。本研究以井冈霉素工业生产菌株吸水链霉菌5008为出发菌株,详细研究了不同碱溶液和不同时间点进行pH冲击时,井冈霉素的分泌情况,发现在发酵开始20h时用氢氧化钠溶液处理效果最好,在早期蛋白合成和残糖消耗速率也比较高。本研究从基因层面出发,通过基因芯片及qRT-PCR技术分析了吸水链霉菌5008在pH冲击之后基因表达的情况,发现与氨基酸代谢、碳代谢、电子呼吸链等生命过程有关的基因都显著上调表达,还有一些转录调控因子与信号转导系统相关基因也上调表达。结合呼吸活性和胞内谷氨酸含量测定,进一步确认了呼吸活性增强,以及谷氨酸含量的提高。综上说明链霉菌通过一系列复杂的机制传递环境刺激信号并作出响应,促使细胞谷氨酸代谢加强,碳代谢流向转变,呼吸加快,最终使得井冈霉素产量提高。论文还描述了一种快速检测井冈霉素发酵过程中污染的方法,通过GC-MS技术结合PCA来分析发酵液气味物质的差异,能够在发酵早期就检测到异常,并且这种方法不受污染微生物种类和发酵培养基种类的影响。
[Abstract]:Jinggangmycin, one of the most effective antifungal antibiotics in agriculture, has excellent control effect on rice sheath blight. Fermentation pH is an important factor affecting the fermentation process of Jinggangmycin, and environmental pressure is an important way to promote the production of secondary metabolites of Streptomyces. However, the research on the pH impact on the fermentation process of Jinggangmycin is limited. In this study, Streptomyces hygroscopicus 5008, an industrial production strain of Jinggangmycin, was used as the starting strain to study the secretion of mycomycin in different alkali solutions and at different time points during pH shock. It was found that sodium hydroxide solution was the best treatment at the beginning of fermentation for 20 h, and the protein synthesis and sugar residue consumption rate were also higher in the early stage. In this study, the gene expression of Streptomyces hygroscopicus 5008 after pH shock was analyzed by gene chip and qRT-PCR technique. The results showed that it was related to amino acid metabolism and carbon metabolism. The genes involved in life processes such as electron respiratory chain were up-regulated, and some transcription regulators and signal transduction system related genes were also up-regulated. Combined with the determination of respiratory activity and intracellular glutamate content, the increase of respiratory activity and glutamate content were confirmed. It is concluded that Streptomyces transmits and responds to environmental stimuli through a series of complex mechanisms, which promotes the enhancement of cell glutamate metabolism, the transformation of carbon metabolism, and the acceleration of respiration, which ultimately leads to an increase in the production of Jinggangmycin. This paper also describes a method for rapid detection of pollution in the fermentation process of Jinggangmycin. The difference of odour substances in fermentation broth can be detected by GC-MS and PCA, which can detect abnormality in the early stage of fermentation. And this method is not affected by the species of contaminated microorganisms and fermentation medium.
【学位授予单位】：浙江大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TQ455;TQ920.1

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