【作者】 刘文桃；

【导师】 封克；

【作者基本信息】 扬州大学 ， 植物营养学， 2009， 硕士

【摘要】 铜绿微囊藻随着水体富营养化的发展,正在全世界蔓延泛滥。这种单细胞蓝藻产生的七肽化合物(微囊藻毒素),能引起人类的肝癌,也会影响水生植物和动物的正常生长,造成严重的生态系统失衡。近年来各国都十分关注这种“生态癌”的治理。虽然己花费巨额投资,进行了大量的研究,但至今尚无突破性进展。近年来随着藻类化感作用研究的开展,有些学者认为利用植物的化感作用可能是解决有毒藻类水华的有效途径。当前研究多以水生植物对藻类的影响为研究对象,而对陆生植物的研究较少。本研究的目的旨在探索一种通过陆生植物对藻类的化感作用防治微囊藻的新途径。本试验通过筛选,确定了高温处理的韭菜水溶性浸提液对铜绿微囊藻(FACHB-905)具有明显的化感抑制作用,研究了不同环境条件下(pH、光照强度、是否曝气、藻初始浓度)韭菜水溶性浸提液对铜绿微囊藻生长的影响及其抑制机理,对韭菜化感物质进行了初步分离。同时对韭菜中化感物质与其所处环境之间的关系作了定性说明,且对如何利用韭菜的化感现象应用于富营养化湖泊的治理与生态修复提出了建议。具体结论如下:(1)预备实验(不同溶剂对化感物质抑藻效果的影响),结果表明:单一化感物质对铜绿微囊藻抑制效果不明显,并且在化感物质发生作用时,溶剂种类和用量起着极其重要的作用。(2)韭菜浸提液对铜绿微囊藻(FACHB-905)生长影响的实验表明,高温处理的鲜韭菜水溶性对铜绿微囊藻存在明显的抑制作用。培养7d后,高温处理的鲜韭菜水溶性浸提液对铜绿微囊藻的抑制率与浸提液浓度的对数线性相关,对铜绿微囊藻的半效应浓度EC50为0.808 g/L。表明韭菜对铜绿微囊藻的化感抑制作用在一定范围内可获得良好的重现。(3)韭菜产生化感物质的活性及浓度受pH、光照强度、是否曝气、藻的起始浓度的波动影响。在培养体系中化感物质对铜绿微囊藻的抑制作用是上述几种因素综合作用的结果。本试验中,化感物质作用最佳的条件为pH9.5、低光照(1000Lx)、培养过程中的曝气、起始浓度为106、107 ind/L条件下抑制效果最好。(4)抑制机理实验研究表明,经高温处理的韭菜水溶性浸提液不但对铜绿微囊藻的超微结构产生了破坏,还对其生理生化各方面产生了影响。具体表现为铜绿微囊藻细胞生长量显著降低,藻体叶绿素a含量下降,膜透性增大,超氧化物歧化酶(SOD)活性、可溶性蛋白含量均呈现先升高后降低的趋势,膜脂过氧化产物丙二醛(MDA)积累量与超微结构所显示的细胞膜的损伤程度相一致。(5)对韭菜化感物质做了初步分离,发现正己烷相的抑藻效果最好,培养周期内抑制率可达90%以上,水相的抑藻率也达到80%以上。正己烷相和水相的EC50为0.26mg/L和0.81mg/L。正己烷相组分的抑藻效果明显好于已报道的化感物质,有着良好的应用前景。更多还原

【Abstract】 Microcystis aeruginosa was overspreading all over the world, especially in severely eutrophicated water bodies. The heptapeptide compound produced by single cell cyanobactcria not only caused human liver cancer, but also affected regular growth of aquatic plant and animal, at least leaded to the serious ecosystem unbalance. Therefore, control of the“ecology cancer”was taken seriously by many countries in recent years. However, breakthrough development in this aspect has not been made as yet, in spite of substantive investments and abundant research work.With studies on algae allelopathy developed, some researchers suggested this may be the effective approach to solve harmful algae blooms lately. Current research work focused more on the impact of aquatic plants on algae, but the study of terrestrial plants was less emphasized. The purpose of this study was aimed to explore a novel approach in biological control of Microcystis by terrestrial plant.Our preliminary experiment showed that the water-soluble extract of leek can inhibit the growth of Microcystis aeruginosa (FACHB-905) effectually, especially when the extract was treated by high temperature. This study was conducted to investigate the effects and mechanisms of the water-soluble extract of leek on Microcystis aeruginosa under different designed conditions including pH, light intensity, aeration, initial concentration of algae, and the allelochemicals of leek was preliminary isolated. In additon, the qualitative relationship between the allelochemicals extracted from leek and the working conditions was analyzed. The effective uses of the allelopathical effects of leek extract to improve the water environment quality were also suggested and discussed in the paper.The results obtained were summarized as follows:(1)The inhibitory effect of single allelochemicals without pretreatment on Microcystis aeruginosa growth was not obvious, and the type and amount of solvent played a very important role when the allelochemicals took effect.(2)The water-soluble extract of fresh leek treated by high temperature inhibited Microcystis aeruginosa (FACHB-905) growth effectually. After 7 days incubation, the log-linear correlation existed between the inhibition rate and the concentration of the extract, and the EC50 was 0.808 g /L .(3)The inhibitory effect of leak extract treated with high temperature was affected by pH, light intensity, aeration and initial concentration of algae, which indicated that the apparent inhibitory effect of leak extract during incubation period was integrated with the interaction between such factors. In this experiment, the optimum conditions for the allelopathy were as follows: pH9.5, low light intensity (1000Lx), aeration, initial concentration of algae 106,107 ind / L.(4) The water-soluble extract of leek treated by high temperature obviously affected cell structure and some physiological indexes which contributed to inhibition of Microcystis aeruginosa growth. Under leak extrat treatment, cell ultra-structure of Microcystis aeruginosa was destroyed and finally disintegrated. Chlorophyll a content and photosynthetic rate declined evidently from the beginning of the treatment while respiratory rate, SOD activity and the content of soluble protein increased during early period then decreased;. Membrane permeability andMDA accumulation was consistent with the degrees of cell membrane destruction under leak extract treatment.(5)The allelochemicals of leek was preliminary isolated, and the best inhibitory effects were observed in N-hexane phase. The inhibition rate of N-hexane during incubation period reached higher than 90%; and that of the aqueous phase was also higher than 80%. The EC50 of N-hexane phase and aqueous phase were 0.26mg / L and 0.81mg / L, respectively. The inhibitory effects of N-hexane phase on algae growth were better than previously reported allelochemicals. Therefore,N-hexane phase of leak extract will have a promising application in algae control.更多还原