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. harveyivia 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.
| 科 Family | 属数 Number of genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) | 属 Genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) |
|---|---|---|---|---|---|---|
| 鹅膏菌科Amanitaceae | 2 | 11 | 5.26 | 鹅膏菌属 Amanita | 10 | 4.78 |
| 小菇科 Mycenaceae | 2 | 12 | 5.74 | 丝盖伞属 Inocybe | 5 | 2.39 |
| 多孔菌科 Polyporaceae | 8 | 14 | 6.70 | 蜡蘑属 Laccaria | 5 | 2.39 |
| 红菇科 Russulaceae | 3 | 23 | 11.00 | 小皮伞属 Marasmius | 6 | 2.87 |
| 小菇属 Mycena | 11 | 5.26 | ||||
| 光柄菇属 Pluteus | 5 | 2.39 | ||||
| 红菇属 Russula | 17 | 8.13 | ||||
| 栓菌属 Trametes | 5 | 2.39 |