本研究目的為評估土肉桂葉(Cinnamomum osmophloeum Leaf)及柳杉(Cryptomeria japonica)精油對退伍軍人菌(Legionella pneumophila)之抑菌效果,並探討精油應用於溫泉水體之可適性。結果發現桂皮醛型(Cinnamaldehyde type)土肉桂葉精油在所有測試精油中抑菌效果最佳,且隨著降低菌液濃度及增加暴露時間,其抑菌效果均顯著上升。而桂皮醛(Cinnamaldehyde)佔桂皮醛型土肉桂葉精油之91.32%,且其抑菌效果顯著優於桂皮醛型土肉桂葉精油(p<0.05),顯示其為桂皮醛型土肉桂葉精油抑制L. pneumophila生長之主要原因之一。而在以實際環境溫泉水為介質,測試桂皮醛型土肉桂葉精油的抑菌效果部分,顯示桂皮醛型土肉桂葉精油在酸性硫酸鹽氯化物泉中之抑菌效果最佳(接觸60分鐘下最小抑制80%細菌之精油濃度為172 ug/mL),在中性碳酸氫鹽泉、弱鹼性碳酸氫鹽泉及酸性硫酸鹽泉中則需添加較高濃度之精油,才可達相當之抑菌效果。 由以上結果顯示桂皮醛型土肉桂葉精油在溫水環境中為對退伍軍人菌有顯著的抑菌作用,建議未來可將其應用於溫泉中以控制退伍軍人菌。
The main purpose of the present study is to investigate the antibacterial effect of essential oils (EO) extracted from Cinnamomum osmophloeum and Cryptomeria japonica against Legionella pneumophila serogroup1 in warm aquatic environment. It was found that Cinnamomum osmophloeum leaf oil of cinnamaldehyde type was the most effective EO in terms of the antibacterial effect against L. pneumophila. Moreover, the antibacterial activity of this EO was increased with increasing the exposure time and decreasing the cell concentration. Cinnamaldehyde, accounting for 91.32% of Cinnamomum osmophloeum leaf oil of cinnamaldehyde type, demonstrated the anti-legionella activity better than Cinnamomum osmophloeum leaf oil of cinnamaldehyde type (p<0.05), which strongly suggests that cinnamaldehyde is responsible for inactivation of L. pneumophila shown in Cinnamomum osmophloeum leaf oil of cinnamaldehyde type. Cinnamomum osmophloeum leaf oil of cinnamaldehyde type was further applied to four kinds of hot spring collected in northern Taipei area. The results showed that Cinnamomum osmophloeum leaf oil of cinnamaldehyde type inactivated L. pneumophila significantly in acid sulphur-chlorine spring water, whereas higher concentrations of Cinnamomum osmophloeum leaf oil of cinnamaldehyde type was required for other three kinds of spring. In conclusion, Cinnamomum osmophloeum leaf oil of Cinnamaldehyde type is the most effective bactericidal agent against L. pneumophila in warm water, which highlights its potential application in recreational hot spring.