铜绿微囊藻溶藻菌EA-1的分离鉴定及溶藻特性

Isolation and identification of an algicidal bacteria strain of EA-1 and algicidal characteristics on Microcystis aeruginosa

从广州流花湖分离获得一株溶藻菌株EA-1,16SrDNA分析表明菌株EA-1属于肠杆菌属(Enterobacter).研究了肠杆菌EA-1对铜绿微囊藻的溶藻效果和溶藻机制.结果表明,对数期EA-1具有最佳溶藻效果,投加比例为10%,初始叶绿素a含量为1.43mg/L时,EA-1能实现3d内完全除藻,叶绿素a含量为2.39mg/L时,共培养6d后,抑制率为84.1%±1.3%.EA-1通过分泌胞外溶藻物质间接溶藻,生理生化响应表明,EA-1无菌滤液胁迫下,藻细胞膜脂过氧化损伤严重,超氧化物歧化酶(SOD)、过氧化氢酶(CAT)和抗坏血酸过氧化物酶(APX)活性先急剧上升后下降.三维荧光光谱(EEM)表明溶藻产物为类腐殖酸,类富里酸和类蛋白类物质.扫描电子显微镜(SEM)显示藻细胞出现褶皱,内陷和萎缩现象.透射电子显微镜(TEM)显示藻细胞破坏过程为:首先,胶质层与细胞壁分离,光合片层变得松散和不规则,内含物被部分降解.随后,光合片层被彻底破坏,DNA核物质和多聚磷酸盐等营养物质颗粒被降解,藻细胞内部结构被完全破坏,藻细胞死亡.

An algicidal bacterium EA-1 was isolated from Liuhua Lake in Guangzhou.The 16 S rDNA analysis showed that the strain EA-1 belongs to the genus Enterobacter sp.The algicidal efficiency and mechanism of Enterobacter sp.EA-1 on Microcystis aeruginosa was studied.The logarithmic phase EA-1 exhibited the best algicidal effect.A 10%inoculation of EA-1 could achieve a complete lysis against Microcystis aeruginosa within 3 days with the initial Chl-a content of 1.43 mg/L.An inhibition rate of 84.1%±1.3%(t=6 d)was attained when the initial Chl-a content reached 2.39 mg/L.EA-1 lysed algae by secreting extracellular algicidal substances.The physiological and biochemical responses indicated that algae suffered serious lipid peroxidation,superoxide dismutase(SOD),catalase(CAT)and ascorbate peroxidase(APX)activities increased dramatically first and decreased subsequently under the oxidative stress of EA-1 sterile filtrate.Three-dimensional fluorescence spectroscopy(EEM)analysis showed that the algae lysates were humic acid-like,fulvic acid-like and protein-like substances.Scanning electron microscopy(SEM)showed that the surface of algae cells appeared wrinkled,invaded and atrophied.Transmission electron microscopy(TEM)showed that the destruction process of algae was as followed:first,the colloidal layer was separated from the cell wall,the photosynthetic lamellae became loose and irregular,the contents were partially degraded.Subsequently,the photosynthetic lamellae were completely destroyed,the DNA nuclear material and nutrient particles such as polyphosphate were degraded,the internal structure of algae cells was completely destroyed and the algae cells died.