肉桂醛抑制哈维弧菌通过接合转移获取外源质粒及其潜在作用机制

Cinnamaldehyde inhibits exogenous plasmid acquisition via conjugative transfer in Vibrio harveyi and its potential mechanism

摘要:

目的 探究肉桂醛对哈维弧菌(Vibrio harveyi)通过接合转移获取外源质粒的影响，并解析其可能的作用机制。方法 以哈维弧菌345为受体菌，以含穿梭质粒pMMB207的大肠杆菌(Escherichia coli)为供体菌，分析不同阶段(处理1：哈维弧菌培养至对数早期；处理2：平板接合过程；处理3：双阶段)肉桂醛处理前后哈维弧菌接合转移效率的变化；检测肉桂醛处理前后哈维弧菌生物膜形成能力的变化；进一步利用qPCR分析处理1和处理2中群体感应相关基因的表达变化。结果 0.5、1、2、4、8 μg/mL肉桂醛处理使处理1中接合转移效率分别下降59%、98%、87%、85%、83%，处理2中分别下降51%、85%、36%、93%、49%；处理3中肉桂醛浓度为1、2、8 μg/mL时接合转移效率分别下降71%、14%、75%。肉桂醛处理后生物膜形成能力无显著变化。在处理1中，肉桂醛处理后群体感应相关基因表达无显著差异(P>0.05)；在处理2中，接合4 h后，仅8 μg/mL肉桂醛处理使luxM、luxN、luxS和luxP基因表达量显著下降1.47-2.94倍(P<0.05)；0.5-8 μg/mL肉桂醛处理使luxR基因表达量下降1.16-3.19倍(P<0.05)。结论 肉桂醛可能通过抑制群体感应信号减少接合转移的发生。本研究阐明了肉桂醛作为天然化合物在调控细菌基因转移及阻断耐药性传播中的潜在作用，可为开发新型抗菌辅助剂提供参考。

Abstract:

Objective To investigate whether cinnamaldehyde affects the acquisition of exogenous plasmids via conjugative transfer in Vibrio harveyi and to elucidate the potential mechanism.Methods V. harveyi 345 was used as the recipient strain, and an Escherichia coli strain harboring the shuttle plasmid pMMB207 served as the donor. The efficiency of exogenous plasmid acquisition by V. harveyi via conjugative transfer was analyzed before and after cinnamaldehyde treatments at three different stages: Treatment 1 (cinnamaldehyde added during the early logarithmic phase of V. harveyi), Treatment 2 (cinnamaldehyde added during the plate-mating process), and Treatment 3 (cinnamaldehyde added during both stages). Changes in biofilm-forming ability of V. harveyi before and after cinnamaldehyde treatments were assessed. Furthermore, qPCR was used to monitor the changes in the expression of quorum sensing (QS)-related genes under Treatment 1 and Treatment 2.Results Cinnamaldehyde at 0.5, 1, 2, 4, and 8 μg/mL reduced the conjugative transfer efficiency by 59%, 98%, 87%, 85%, and 83% under Treatment 1 and by 51%, 85%, 36%, 93%, and 49% under Treatment 2, respectively. Under Treatment 3, cinnamaldehyde at 1, 2, and 8 μg/mL decreased the conjugative transfer efficiency by 71%, 14%, and 75%, respectively. Cinnamaldehyde treatments did not significantly alter biofilm formation. Under Treatment 1, cinnamaldehyde led to no significant changes in the expression of QS-related genes (P>0.05). Under Treatment 2, after 4 h of conjugation, the treatment with 8 μg/mL cinnamaldehyde downregulated the expression of luxM, luxN, luxS, and luxP by 1.47 to 2.94 folds (P<0.05). Meanwhile, treatments with 0.5-8 μg/mL cinnamaldehyde downregulated luxR expression by 1.16 to 3.19 folds (P<0.05).Conclusion Cinnamaldehyde suppresses conjugative plasmid transfer, most likely by attenuating quorum sensing (QS). This study elucidates the role of cinnamaldehyde as a natural compound in regulating bacterial gene transfer and the potential spread of antibiotic resistance, providing a reference for the development of novel antibacterial adjuvants.