【作者】 杨佳；

【导师】 鲜啟鸣；

【作者基本信息】 南京大学 ， 环境科学， 2012， 硕士

【摘要】 蓝藻水华已经成为我国面临的重大环境问题之一。其形成过程中经常伴随着不同藻类的更替,探究不同蓝藻间的化感作用及其在竞争更替过程中的贡献,分析潜在的化感物质,可以揭示水华蓝藻优势种的成因,并为蓝藻水华形成机制提供理论依据。本文以我国富营养化浅水湖泊中两种常见的水华蓝藻,铜绿微囊藻(Microcystis aeruginosa)和惠氏微囊藻(Microcystis wesenbergii)为研究对象。在实验室条件下,通过混合培养和过滤液培养两种方式探讨微囊藻种间的化感作用。铜绿微囊藻和惠氏微囊藻混合培养时,两者存在相互抑制作用。其中铜绿微囊藻对惠氏微囊藻有强烈的抑制作用,且主要是化感作用,而惠氏微囊藻对铜绿微囊藻的抑制作用则较弱。当两者藻密度为0.5×106个·mL-1以上时,培养9d后惠氏微囊藻的抑制率在80%以上。处于对数期的铜绿微囊藻过滤液能够抑制惠氏微囊藻的生长,当惠氏微囊藻初始藻密度为0.5×106个·mL-1以下时,连续滴加对数期的铜绿微囊藻过滤液后,惠氏微囊藻的生长受到了极显著抑制(p<0.01)。与之相反,对数期的惠氏微囊藻过滤液则显著地促进铜绿微囊藻的生长。用HLB-SPE小柱富集对数生长期的铜绿微囊藻过滤液,依次用正己烷、二氯甲烷和甲醇洗脱,所得的萃取物分别进行抑藻实验和定性分析。三种萃取物对惠氏微囊藻的抑藻活性随着洗脱溶剂极性的增强而增加,其中甲醇萃取物的抑藻活性最强。通过液质联用(LC-MS)在甲醇萃取物中检出的微囊藻毒素LR(microcystin-LR, MC-LR)是潜在的化感物质。同时,在二氯甲烷萃取物中检出分子量为678.5的潜在化感物质,但其具体结构尚需进一步确定。更多还原

【Abstract】 Cyanobacteria bloom has been becoming one of the most serious environmental problems in China. The formation of cyanobacteria bloom is often accompanied by the succession of different algae. Studing the allelopathic effect among different cyanobacteria and its contribution in competition process and identifying potential allelochemicals can provide important theoretical basis on the mechanism of the succession of dominant cyanobacteria species and cyanobacteria bloom-forming.Microcystis aeruginosa and Microcystis wesenbergii are two common cyanobacteria species in the eutrophic shallow lakes in China. In laboratory, allelopathic effect between the two cyanobacteria was studied by co-cultivation and cultivation with cell-free filtrates. The co-cultivation experiment showed that the mutual inhibition effect took place between them. M. wesenbergii was inhibited strongly due to the allelopathic effect from M. aeruginosa, and M. aeruginosa was also stressed slightly. When the initial cell density of both algae was more than0.5x106cells-mL-1, the inhibition rate of M. wesenbergii was more than80%after9days cultivation. Meantime, the growth of M. wesenbergii was also inhibited by adding cell-free filtrates from M. aeruginosa in exponential phase. M. wesenbergii was restrained significantly (p<0.01) when the initial cell density of M. wesenbergii was less than0.5x106cells-mL-1and the filtrates were added continuously into the culture solution. On the contrary, the growth of M. aeruginosa was promoted by adding cell-free filtrates from M. wesenbergii.The cell-free filtrate of M. aeruginosa was extracted by HLB-SPE column. The different extracts were obtained by eluting with n-hexane, dichloromethane and methanol in turn. The extracts were used for algicidal bioassay with M. wesenbergii and qualitative analysis with GC-MS and LC-MS. The results showed that the higher polarity the eluting solvents were, the stronger allelopathic effect of the extracts were, and the methanol extract had the strongest inhibtion activity to M. wesenbergii. Microcystin-LR, a potential allelochemical, was identified by HPLC and LC-MS in the methanol extract. Another potential allelochemical, was detected in the extract of dichloromethane, its molecular weight was678.5, but its chemical structure needed further research.更多还原