The Grazing and Microcystin Degradation Effects of <i>Poterioochromonas malhamensis</i> on <i>Microcystis aeruginosa</i>

目的：研究在高密度比(1:50)下杯棕鞭藻对铜绿微囊藻的摄食效率、降解藻毒素(MC-LR)效率以及该过程中的生理代谢变化。方法：通过室内微囊藻和杯棕鞭藻共培养试验，测定二者在不同时期密度变化以及谷胱甘肽(GSH)含量、超氧化物歧化酶(SOD)和过氧化氢酶(CAT)活性。结果：本研究发现并分离纯化一株可以摄食微囊藻的棕鞭藻，经形态学特征鉴定为Poterioochromonas属的杯棕鞭藻Poterioochromonas malhamensis，通过室内实验发现，杯棕鞭藻在降解过程中通过增加GSH含量、SOD和CAT活性，加速藻毒素降解速率并减少活性氧(ROS)和MC产生的氧化损伤。结论：杯棕鞭藻可以通过改变其自身生理代谢过程来摄食微囊藻并降解藻毒素，以上研究对合理利用生物策略控制微囊藻水华具有关键指导意义。Objective: The study investigates the grazing efficiency of Poterioochromonas malhamensis on Microcystis aeruginosa under high density ratio (1:50), its microcystin (MC-LR) degradation efficiency, and the changes of physiological metabolic during this process. Methods: Co-culture experiments of Microcystis aeruginosa and Poterioochromonas malhamensis were conducted under laboratory conditions. Temporal variations in cell densities, glutathione (GSH) content, as well as superoxide dismutase (SOD) and catalase (CAT) activities were measured. Results: A strain of Poterioochromonas malhamensis capable of grazing Microcystis aeruginosa was isolated and purified, which was morphologically identified as Poterioochromonas malhamensis. Laboratory experiments revealed that during the degradation process, Poterioochromonas malhamensis enhanced GSH content and increased SOD and CAT activities, thereby accelerating MC degradation rate and mitigating oxidative damage caused by reactive oxygen species (ROS) and MC. Conclusion: Poterioochromonas malhamensis can graze Microcystis aeruginosa and degrade algal toxins by modulating its physiological metabolic processes. These findings provide critical guidance for developing biological strategies to control blooms of Microcystis aeruginosa.