山苍子精油对MRSA生物被膜及其调控基因ica A的抑制机理研究

Antibacterial mechanism of Litsea cubeba oil on methicillin-resistant Staphylococcus aureus(MRSA)biofilm and its regulatory gene ica A

耐甲氧西林金黄色葡萄球菌(methicillin-resistant Staphylococcus aureus,MRSA)是一种常见的人畜共患病原菌,极易在食品加工设备表面生成生物膜,增加食物污染的风险。山苍子精油作为植物源天然提取物,对S.aureus有良好的抗菌效果,但其抗MRSA生物膜能力及作用机制还知之甚少。本实验研究了山苍子精油对MRSA生物被膜及其多糖细胞间黏附素(PIA)的调控基ica A的抗菌机制。结果表明:山苍子精油对MRSA生物膜的MBIC是2.0mg/mL,MBEC是4.0mg/mL;由菌落计数法可知,山苍子精油的抗MRSA生物膜能力与精油浓度和处理时间呈正相关。抗生物膜机制的初步探索结果表明,MRSA生物膜的代谢水平和细胞外聚合物(胞外多糖,胞外蛋白和胞外DNA)的形成受到山苍子精油的抑制。此外,在分子水平上的实验结果表明,山苍子精油可以显著抑制MRSA生物膜中ica A基因的转录水平。

Methicillin-resistant Staphylococcus aureus(MRSA)has become a common pathogen of zoonosis and it is easy to form biofilm on the surface of food equipment,which will significantly increase the risk of food contamination.Litsea cubeba oil,a plant extract,possesses a good antibacterial effect on S.aureus,but its antibacterial effect on MRSA biofilm and its mechanism have not been studied in detail.This experiment investigated the mechanism of Litsea cubeba oil against MRSA biofilm and regulatory gene ica A of PIA.The results showed that Litsea cubeba oil against MBIC in MRSA biofilm was 2.0 mg/mL and against MBEC was 4.0 mg/mL.The total number of colonies showed that bactericidal was positively correlated with the concentration of Litsea cubeba oil and treatment time.The preliminary exploration of anti-biofilm mechanism showed that the metabolic level of MRSA biofilm and formation of extracellular polymers(extracellular polysaccharide,extracellular protein and extracellular DNA)were inhibited by Litsea cubeba oil.In addition,molecular level study indicated that Litsea cubeba oil could significantly inhibit the transcription of ica A gene in MRSA biofilm.