岩兰草油对淡水藻类的抑制作用

Studies on the inhibition of vetiver oil to freshwater algae

利用植物分泌的化感物质进行藻类控制已成为国内外生态环境领域研究的热点之一。首次探讨了岩兰草油的抑藻效应,建立了岩兰草油对铜绿微囊藻和斜生栅藻两种藻共培养时抑制作用的数学模型,采用GC-MS分析方法对岩兰草油中主要成分进行了鉴定。结果表明:岩兰草油对铜绿微囊藻和斜生栅藻在单独和共培养状态下均有良好的抑制作用,对单独培养的铜绿微囊藻和斜生栅藻抑制作用的EC50分别为0.20和0.30 m L/L,说明岩兰草油对蓝藻(铜绿微囊藻)的抑制效果明显好于对绿藻(斜生栅藻)。岩兰草油的主要成分为具有良好抑藻作用的倍半萜类物质,而所建立的岩兰草油对两藻共培养状态下抑制作用的数学模型可以求出在任何时间节点上铜绿微囊藻和斜生栅藻的种群密度以及要达到抑藻最佳状态的岩兰草油浓度。该研究对水华藻类的控制有较重要的理论与应用价值。

Eutrophication tends to stimulate rapid explosive growth of cyanobacteria,leading to water bloom. Some cyanobacteria can release neurotoxins,hepatoxins,dermatoltoxins,gastrointestinal toxins and cytotoxins,which can be toxic to humans and aquatic animals. How to control the undesired cyanobacteria growth in an aquatic ecosystem？ It has been reported that allelopathy and allelochemicals of aquatic macrophytes have certain effects in dealing with this tough issue. It is also reported that vetiver,an emergent plant with flourishing roots,can not only absorb water bodies nitrogen and phosphorus but also secret some allelochemicals to inhibit the growth of cyanobacteria. In the planned experiment on some powerful allelochemicals that can control the growth of cyanobacteria or other floating algae effectively,the inhibitory effects of vetiver oil on Microcystis aeruginosa and Scenedesmus obliquus,when the two algae species were cultured alone or cultured together,were respectively found and discussed for the first time in this study,and the mathematical models were also established about the inhibition of vetiver oil on those two algae species in mixed culture. Moreover,the composition of vetiver oil was assayed and identified by GC-MS. The results showed that vetiver oil had excellent inhibition on M.aeruginosa and S. obliquus in both pure and mixed culture. The EC50 of vetiver oil on these two algae species in pure culture were 0. 20 and 0. 30 m L / L respectively,which indicated that the inhibitory effects of vetiver oil,like most other aquatic macrophyte and allelochemicals,has species specificity,i. e.,the inhibition of vetiver oil on cyanobacteria（ M.aeruginosa） is much better than that on green algae（ S. obliquus）. Because cyanobacterial dominance is most pronounced during the summer months,there is the huge potential for vetiver oil to develop an effective biological cyanobacterial inhibiting agent. The allelochemicals in vetiver oil assayed and identified by GC-MS showed that the main chemicalcomponents of vetiver oil are sesquiterpenes,including 1-cyclohexyl-butanone,terpineol,cedar alcohol,cuparene,α-chamigrene,δ- cadinene,α- cadinene and- cedrene in addition to some alkanol and ketone,and among them sesquiterpenes have the most powerful allelopathy according to the papers reported by far. The mathematic models of mixed culture established through the analysis of the results of the experiment could provide the species densities of M. aeruginosa and S. obliquus at any time point as well as that of the concentration of vetiver oil for the best inhibition. Because the mathematic model related to allelopathy studied relatively very limited,the mathematical model undoubtedly has some reference application value for using allelochemicals to inhibit the growth of algae,especially for two algae species in mixed culture. All in all,this research has important theoretical and application value on prevention and control of cyanobacteria blooms,as well as comprehensive utilization of vetiver oil.