The dynamicsand mechanism of the antimicrobial activity of tea tree oil against bacteria and fungi

• 作 者: Wenru Li Hailing Li Qingshan Shi
• 机 构: State Key Laboratory of Applied Microbiology Southern China,Guangdong Provincial Key Laboratory of M
• 出 处: 第六届全国农业微生物研究及产业化研讨会、第十五届全国杀虫微生物学术研讨会、第十一届全国虫生真菌学术研讨会
• 发表日期: 2016年10期
• 关键词: Tea tree oil Escherichia coli Staphylococcus aureus Candida albicans Aspergillus

　　Tea tree oil(TTO)is a yellow liquid extracted from Melaleuca alternifolia.Although the antimicrobial activity of TTO has been known for a long time,its specific antimicrobial effects and mechanism underlying these remain poorly characterized.The present study investigatedthe chemical composition of TTO,and the dynamics and mechanism of its antimicrobial activities in two bacterial and two fungal strains.Gas chromatography-mass spectrometry analysis identified alkenes and alcohols as the main constituents of TTO.Terpinen-4-ol was the most abundant individual component,accounting for approximately 23% of the TTO.Poisoned food technique assessment showed that the minimum inhibitory concentrations of TTO for bacterial strains(E.coli and S.aureus)and fungal strains(C.albicans and A.niger)were 1.08 mg/mL and 2.17 mg/mL,respectively.Antimicrobial dynamic curves showed that with increasing concentrations of TTO,the rate of cell killing and the duration of growth lag phase increased correspondingly.These data indicated that TTO produced concentration and time-dependent antimicrobial effects.The minimum bactericidal and fungicidal concentrationsof TTO were 2.17 mg/mL,4.34 mg/mL,and 4.34 mg/mL against E.coli,S.aureus,and C.albicans,respectively.However,A.niger conidia were not completely eradicated,even after 3 days in the presence of 17.34 mg/mL TTO.Transmission electron microscopy images indicated that TTO penetrated the cell wall and cytoplasmic membrane of all the tested bacterial and fungal strains.TTO may also penetrate fungal organelle membrane.These findings indicated that TTO maybe exerts its antimicrobial effects by compromising the cell membrane,resulting in loss of the cytoplasm and organelle damage,which ultimate leads to cell death.