基于AI-2介导的类植物乳杆菌生物被膜态与浮游态抗胁迫能力比较与分析

Stress Resistance of Biofilm and Planktonic Cells of Lactobacillus paraplantarum L-ZS9 Regulated by Autoinducer 2

采用平板活菌计数法比较被膜态及浮游态的类植物乳杆菌L-ZS9经热处理、酸处理、胆盐处理后的存活率,结果表明被膜态菌体具有更强的抗胁迫能力;通过实时荧光定量聚合酶链式反应的方法比较被膜态及浮游态菌株L-ZS9的胁迫相关基因atpβ、atpε、clp、psp C、ccpA及群体感应信号分子自诱导物(autoinducer 2,AI-2)合成关键基因lux S的转录水平,结果表明被膜态菌体的基因转录水平显著高于浮游态;通过报告菌株发光检测法比较被膜态及浮游态菌株上清液中AI-2的活性,结果表明被膜态菌体上清液中AI-2的活性显著高于浮游态;且外源信号分子AI-2可以调控基因atpβ、atpε、clp、ccpA、luxS的转录水平。结果说明生物被膜不仅可以提供物理防御作用,而且其细胞个体的基因转录水平与浮游态也有所不同,且群体感应系统在被膜的形成与调控中发挥着重要作用。本研究为开发高活力益生菌功能食品提供了新的思路和理论基础。

The present study compared the heat, acid and bile resistance of biofilm and planktonic cells of L-ZS9 by colony counting method. The results showed that biofilm cells had stronger stress resistance than their planktonic counterpart. The transcriptional levels of the stress resistance-related genes atpβ, atpε, clp, psp C and ccp A and the lux S gene encoding the quorum sensing signal autoinducer 2（AI-2） synthase were investigated in biofilm and planktonic cells through realtime PCR. The results showed that the transcriptional levels of these genes were up-regulated in biofilm cells compared to planktonic cells. AI-2 activity were measured by its ability to induce luminescence in the reporter strain Vibrio harveyi BB170 and the results showed that the supernatant of biofilm cells had higher AI-2 activity than planktonic cells. Exogenous AI-2 could regulate the transcriptional levels of the atpβ, atpε, clp, ccp A and lux S genes. This study suggested that biofilm protected the cells by physical defense and biofilm cells differed from planktonic cells in terms of the transcriptional levels of the investigated genes. The quorum sensing system played an important role in the formation and regulation of biofilm. This work has laid a foundation for producing functional foods based on biofilm probiotics with high activity.