植物精油对大菱鲆弧菌的体外和体内抗菌活性

In vitro and in vivo antibacterial activity of essential oils against Vibrio scophthalmi isolated from farmed turbot Scophthalmus maxius

摘要:

【目的】研究天然植物精油对大菱鲆弧菌的体外和体内抗菌活性。【方法】采用纸片扩散法和微量肉汤稀释法对14种植物精油或其组分的体外抑菌活性进行检测；通过细菌形态透射电镜观察、胞内乳酸脱氢酶及核酸释放研究山苍子精油对大菱鲆弧菌的膜损伤作用；采用大菱鲆人工攻毒感染实验研究山苍子精油的体内抗菌作用。【结果】14种植物精油或其组分对大菱鲆弧菌具有不同程度的抑制效果，其中肉桂醛的抗菌活性最强，最低抑菌浓度为0.25 μL/mL；百里香酚、丁香酚、柠檬醛和山苍子的抗菌活性次之，最低抑菌浓度为0.5 μL/mL；山苍子精油可破坏大菱鲆弧菌的细胞膜，并导致胞内蛋白酶和核酸外泄；经200 μL/L山苍子精油浸浴后，大菱鲆攻毒后死亡率由对照组50%降至0。【结论】富含芳香醛、芳香酚和柠檬醛的植物精油对大菱鲆弧菌具有良好抗菌活性，有望替代抗生素用于大菱鲆弧菌病的防治。

Abstract:

[Objective] To evaluate the antibacterial activity of essential oils against Vibrio scophthalmi HZ-C1 isolated from farmed turbot Scophthalmus maxius in vitro and in vivo. [Methods] The paper disc diffusion method and microbroth dilution technique were employed to determine the antibacterial activity of 14 essential oils. Cell membrane disruption induced by Litsea cubeba oil was examined by transmission electron microscopy (TEM), and by measuring the release of intracellular lactate dehydrogenase (LDH) and 260 nm absorbing material. Meanwhile, antibacterial activity of Litsea cubeba oil in vivo was investigated using a turbot model of vibriosis by intraperitoneal injection. [Results] The 14 essential oils showed different antibacterial activities against V. scophthalmi HZ-C1, and cinnamaldehyde had the highest activity with a minimum inhibitory concentration (MIC) of 0.25 μL/mL, followed by thymol, eugenol, citral and Litsea cubeba oil with a MIC of 0.5 μL/mL. Litsea cubeba oil can disrupt the plasma membrane of V. scophthalmi HZ-C1 and cause the leakage of protease and nucleic acid. After immersing in a bath containing 200 μL/L Litsea cubeba oil, the mortality of turbots infected by V. scophthalmi was reduced from 50% to 0. [Conclusion] Essential oils rich in aromatic aldehyde, phenolic compounds and citral show high antibacterial activities against V. scophthalmi HZ-C1, and thus have the potential to replace the use of antibiotics for treating vibriosis in farmed turbot.