Wu Donghao, Yang Caiyun, Zhang Xian, Hou Xiping, Zhang Siqi, Dai Xianzhu, Zhang Xiaohui, Igarashi Yasuo, Luo Feng
Research Center of Bioenergy and Bioremediation, College of Resources and Environment, Southwest University, Chongqing 400715, PR China.
State Cultivation Base of Eco-agriculture for Southwest Mountainous Land, Department of Environmental Sciences and Engineering, College of Resource and Environment, Southwest University, Chongqing 400716, China.
Sci Total Environ. 2022 Feb 1;806(Pt 4):150719. doi: 10.1016/j.scitotenv.2021.150719. Epub 2021 Oct 1.
Cyanobacterial blooms significantly decrease water quality and can damage ecosystems and, as such, require efficient control methods. Algicidal bacteria and their associated substances are promising tools for controlling cyanobacterial blooms; however, their specific algicidal mechanisms remain unclear. Therefore, the current study sought to investigate the algicidal mechanism of tryptoline (1,2,3,4-tetrahydro-9 h-pyrido[3,4-b]indole) against Microcystis aeruginosa, with a specific focus on the contribution made by reactive oxygen species (ROS), the underlying mechanisms of ROS increase, as well as the photosystem response. Results show that the algicidal ratio of tryptoline significantly and positively correlates with algal ROS. Moreover, 93.79% of the algicidal ratio variation is attributed to ROS in the tryptoline group, while only 47.75% can be attributed to ROS in the tryptoline + N-acetyl-L-cysteine (NAC) group, where ROS are partially scavenged by NAC. In the presence of tryptoline, algicidal effect and ROS levels were significantly enhanced in the presence of light as compared to those in the dark (P < 0.001). Hence, the increase in ROS production attributed to tryptoline is primarily affected by the presence of light and photosynthesis. Additionally, tryptoline significantly reduces F/F, PI, ET/RC, and the expression of psaB and psbA genes related to photosynthesis, while increasing V and DI/RC (P < 0.05). These results suggest that tryptoline hinders algal photosynthesis by significantly decreasing photosynthetic efficiency and carbon assimilation, inhibiting photochemical electron transfer, and increasing closed reaction centers and energy loss. Moreover, following partial blockade of the photosynthetic electron transfer from Q to Q by diuron (3-(3-4-dichlorophenyl)-1,1-dimethylurea), the ROS of algae exposed to tryptoline is significantly decreased. Thus, tryptoline inhibits electron transfer downstream of Q, which increase the number of escaping electron and thereby increase ROS generation. Collectively, this study describes the algicidal mechanism of tryptoline against M. aeruginosa and highlights the critical factors associated with induction of algicidal activity.
蓝藻水华会显著降低水质，并可能破坏生态系统，因此需要有效的控制方法。杀藻细菌及其相关物质是控制蓝藻水华的有前景的工具；然而，它们具体的杀藻机制仍不清楚。因此，本研究旨在探究色胺（1,2,3,4-四氢-9H-吡啶并[3,4-b]吲哚）对铜绿微囊藻的杀藻机制，特别关注活性氧（ROS）的作用、ROS增加的潜在机制以及光系统的反应。结果表明，色胺的杀藻率与藻类ROS显著正相关。此外，色胺组中93.79%的杀藻率变化归因于ROS，而在色胺+N-乙酰-L-半胱氨酸（NAC）组中，只有47.75%可归因于ROS，其中ROS被NAC部分清除。在有光条件下，与黑暗条件相比，存在色胺时杀藻效果和ROS水平显著增强（P<0.001）。因此，色胺导致的ROS产生增加主要受光照和光合作用的影响。此外，色胺显著降低F/F、PI、ET/RC以及与光合作用相关的psaB和psbA基因的表达，同时增加V和DI/RC（P<0.05）。这些结果表明，色胺通过显著降低光合效率和碳同化、抑制光化学电子传递以及增加封闭反应中心和能量损失来阻碍藻类光合作用。此外，在通过敌草隆（3-(3,4-二氯苯基)-1,1-二甲基脲）部分阻断从Q到Q的光合电子传递后，暴露于色胺的藻类的ROS显著降低。因此，色胺抑制Q下游的电子传递，这增加了逃逸电子的数量，从而增加ROS的产生。总体而言，本研究描述了色胺对铜绿微囊藻的杀藻机制，并突出了与杀藻活性诱导相关的关键因素。
