一株溶藻细菌对铜绿微囊藻的溶藻机理初探

为确定溶藻细菌S7（Chryseobaterium）对铜绿微囊藻的溶藻方式,分别采用高温灭菌（121~123℃）、离心（10 000 r.min-1）、0.22μm滤膜过滤等方式对S7菌液进行处理,检测其对铜绿微囊藻的去除效果。并通过对溶藻过程中叶绿素a和丙二醛（MDA）含量的测定,藻细胞显微结构的观察和细胞成分的红外光谱分析,初步探讨菌株S7对铜绿微囊藻的作用机理。结果表明,S7是通过释放胞外活性物质间接溶藻,该物质具有很强的热稳定性,不属于蛋白质类物质。该活性物质对铜绿微囊藻的叶绿素a有明显的去除效果,并可导致藻细胞膜脂过氧化产物MDA积累量的显著提高和藻细胞解体。藻细胞红外光谱分析表明,经过溶藻物质作用的藻细胞,其蛋白质结构遭到破坏。通过试验结果,推测出菌株S7的溶藻机理：溶藻物质先损伤铜绿微囊藻的细胞壁和粘质胶被,然后通过改变膜的选择透过性进入藻细胞内部,分解叶绿素a,破坏蛋白质,造成藻体正常生理功能的丧失,最终导致藻细胞破裂。

Primary research on algicidal mechanism of an algae-lysing bacterium to Microcystis aeruginosa

The removing effects of algae-lysing bacterium S7（Chryseobaterium） with different treatments on the chlorophyll-a of Microcystis aeruginosa were detected to find its algicidal method.These treatments included high temperature（121~123 ℃）,centrifugation（10000 r·min-1）,and filtration with micropore membrance of 0.22 μm.The algicidal mechanism of algae-lysing bacterium S7 to Microcystis aeruginosa was investigated by measuring the content of chlorophyll-a and MDA,observing microstructure of algal cells in the algae-lysing process and analyzing algal components by infrared spectroscopy.Results showed that strain S7 killed Microcystis aeruginosa indirectly by secreting extracellular active substances which had strong thermo-stability and was not protein.These active substances not only had significant removing effects on chlorophyll-a,but also could result in remarkable growth of MDA and effectively dissolve algal cells.The analysis of algal cells by infrared spectroscopy indicated that the protein of Microcystis aeruginosa was destroyed.So the algae-lysing mechanism was speculated as following： algicidal substances firstly destroyed the cell wall and mucilage envelope of Microcystis aeruginosa,then entered into algal cells by changing selective permeability of the cell membrane,and damaged the chlorophyll-a and protein.Finally the cells of Microcystis aeruginosa lysed resulting from the loss of normal biological function.