溶藻细菌筛选及溶藻活性物质对铜绿微囊藻生理活性的影响

SCREENING OF ALGAE-LYSING BACTERIA AND THE EFFECTS OF ALGAELYSING ACTIVE SUBSTANCES ON THE PHYSIOLOGICAL ACTIVITIES OF MICROCYSTIS AERUGINOSA

  • 摘要: 从太湖水华水体中分离纯化细菌, 再将细菌的LB液体和固体斜面纯培养物分别收集后感染铜绿微囊藻(Microcystis aeruginosa)细胞, 从中筛选出7株具有溶藻活性的细菌, 并对其中一株溶藻细菌THW7的溶藻方式及溶藻活性物质对铜绿微囊藻生理活性的影响进行了初步研究。结果表明: 仅采用细菌的LB液体纯培养物进行溶藻细菌筛选会存在误筛或高估溶藻效率的风险, 而采用细菌的固体斜面纯培养物进行筛选则可避免以上风险; 溶藻细菌THW7通过分泌胞外活性物质的方式间接溶藻; 在THW7无菌滤液胁迫下, 铜绿微囊藻的生长受到显著抑制(P<0.01), 10d溶藻效率可达94.38%, 光合系统活性也显著降低(P<0.01), MDA含量积累, SOD、POD、CAT活性整体呈现先升高后降低的趋势且显著高于对照组(P<0.01)。推测菌株THW7分泌的溶藻活性物质可能作用于铜绿微囊藻细胞的光合系统Ⅱ, 阻碍电子传递, 抑制其光合作用过程, 并对藻细胞产生氧化损伤, 破坏藻细胞细胞膜的完整性, 从而实现溶藻作用。

     

    Abstract: Bacteria were isolated and purified from Taihu Lake, where algal blooms occur annually. We used LB liquid and solid slant pure culture solutions of bacteria to infect Microcystis aeruginosa cells, which resulted in the identification of seven strains of bacteria with algae-lysing activity. The method by which the algae-lysing bacterium THW7 lyses algae and the effects of its algae-lysing active substances on the physiological activities of Microcystis aeruginosa were preliminarily studied. The results showed that there was a risk of failed screening or overestimating the efficiency of algae-lysing bacteria when using only LB liquid pure culture solution to screen algae-lysing bacteria, and this risk could be avoided by using the solid slant pure culture solution of bacteria. The algae-lysing bacterium THW7 indirectly lysed algae by secreting extracellular active substances. When treated with the aseptic filtrate of THW7, the growth of Microcystis aeruginosa was significantly inhibited (P<0.01), and the algae-lysing efficiency reached 94.38% on the 10th day. Additionally, the activity of the photosynthetic system significantly decreased (P<0.01); the MDA content accumulated; and the activities of SOD, POD and CAT generally increased first and then decreased and were significantly higher in the treatment group than that in the control group (P<0.01). The algae-lysing active substances secreted by strain THW7 may act on photosynthetic system II of Microcystis aeruginosa cells, thus preventing electron transfer and inhibiting the photosynthetic process. These substances also induced oxidative damage in the algal cells and destroyed the integrity of the algal cell membrane to achieve the algae-lysing effect.

     

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