目的 筛选高效溶藻菌，初步观察其对铜绿微囊藻的溶藻效果。方法 从处理生活污水的活性污泥中分离菌株，将其接种至微囊藻培养液中，通过观察培养液颜色和藻细胞数量的变化，初步筛选出溶藻菌。重复上述过程3次，并用溶藻率来初步评价其溶藻效果，获得较为高效的溶藻菌。用PCR的方法，对高效菌株的16S rDNA进行测序并与GeneBank对比，鉴定其种属。运用透射电子显微镜观察藻类在溶藻菌作用下48 h内发生的形态学变化，证实溶藻效果。结果 从活性污泥中分离得到一株高效溶藻菌，命名为N25-2（以下简称为N25）。经过16S rDNA鉴定，该菌与芽孢杆菌（Bacillus SP.）或纺缍形赖氨酸芽孢杆菌（Lysinibacillus fusiformis）的匹配度均为99%。当培养液中藻的数量达到1×10⁶个/mL，细菌的数量达到1×10⁶ cfu/mL时，在48 h内，该菌的溶藻率达到72%以上。透射电子显微镜观察发现，经过N25处理后，微囊藻出现空泡增加，多面体深染，藻胆体增加，质壁分离和内部结构破坏等形态学改变。结论 N25具有较好的溶藻效果，能诱导微囊藻出现多种形态学改变，其溶藻机制可能是细菌分泌物导致藻类细胞死亡所致，但需进一步研究证实。

Objective To isolate high efficient algicidal bacteria, and investigate their algicidal effect on Microcystis aeruginosa. Methods Bacteria were isolated from activated sludge, and were inoculated in Microcystis aeruginosa culture fluid. Algicidal bacteria were screened through observation of color of culture fluid and number of Microcystis aeruginosa. Algicidal efficiency was evaluated by calculating the algicidal rates, and high efficient algicidal bacteria were obtained. PCR was employed to sequence 16S rDNA of high efficient algicidal bacteria, and was aligned with the data of Genebank to identify the target bacterium. Transmission electronic microscopy was used to observe the morphological changes in the algae treated with algicidal bacteria for 48 h. Results A strain of algicidal bacterium was isolated from activated sludge samples, which was designated as N25-2 (hereinafter to be referred as N25). It was identified by 16S rDNA that the match rates of N25 with Bacillus SP. and Lysinibacillus fusiformis were both 99%. When the concentration of Microcystis aeruginosa was over 1×10⁶/mL and the concentration of bacteria reached 1×10⁶ cfu/mL, the algicidal rate was higher than 72% within 48 h. Transmission electronic microscopy revealed that there were increased vacuoles, deep staining of polyhedrons and increased phycobilisomes in Microcystis aeruginosa after being treated with N25, and the main morphological changes were plasmolysis and inner structural damage. Conclusion N25 has a high algicidal efficiency, and the algicidal mechanism may be associated with the secretion of bacteria, which needs further study.