戊糖片球菌热胁迫应答机制探究

A study on heat stress response of Pediococcus pentosaceus

目的以发酵柚子皮中分离到的戊糖片球菌WPPE03、WPPE04作为研究对象,用标准株CGMCC1.2695作为对照,探索其热胁迫相关机制。方法通过平板计数法,确定戊糖片球菌的热适应条件和热致死条件;采用扫描电子显微镜观察细胞热应激前后形态学变化;应用RT-qPCR分析热休克蛋白及细胞膜脂肪酸合成相关基因转录水平变化,阐明热胁迫机制。结果确定了三株戊糖片球菌热适应条件(47℃,60min)和热致死评价条件(62℃,15min);发现了热致死条件处理菌体,膜表面会出现凹陷、皱褶,部分菌体出现破裂、胞内物质外溢等现象,而热致死条件处理前先经过热适应处理,菌体破裂现象明显减少;同时,证明了热应激处理过程中,相关热休克蛋白基因表达显著上调(P<0.05),脂肪酸合成相关基因表达发生了变化。结论研究戊糖片球菌的热应答相关机制,可为合理开发、利用具有发酵性能的戊糖片球菌提供借鉴。

Abstract： Objective To study the mechanism of heat stress response of Pediococcus pentosaceus WPPE03 and WPPE04 isolated from fermented pomelo peel, with the comparison of type strain of P. pentosaceus CG- MCC1. 2695. Methods The heat adaptation and lethal temperature was tested by plate counting method, the ceil morphology was checked through scanning electron microscope, and the mRNA levels of genes of heat shock protein and which involved in fatty acid synthesis were analyzed by reverse transcription-quantita- tive PCR （RT-qPCR） . Results The adaptation and lethal conditions were 47℃ for 60 rain and 62℃ for 15 min, respectively. The cell surface appeared sunken and wrinkles, and part of the cells were broken with intracellular material spilled out etc. However, the cell morphology was protected when there was a heat ad- aptation. In addition, expression of heat shock protein relevant genes were significantly up-regulated under heat stress （P〈0.05）, and the genes involved in fatty acid synthesis had up-regulated and down-regulated. Conclusion The heat response mechanism of P. pentosaceus may provide the theory reference for utilization of P. pentosaceus in the fermentation industry.