期刊
SCIENCE OF THE TOTAL ENVIRONMENT
卷 806, 期 -, 页码 -出版社
ELSEVIER
DOI: 10.1016/j.scitotenv.2021.150719
关键词
Cyanobacterial bloom; Algicidal activity; Photosystem; Electron transport; Water quality; light conditions
资金
- Natural Science Foundation Project of CQCSTC [cstc2018jcyjAX0629]
- National Natural Science Foundation of China [31600095]
- Fundamental Research Funds for the Central Universities [XDJK2020B068, XDJK2020B070]
This study investigated the algicidal mechanism of tryptoline against Microcystis aeruginosa and found that its algicidal effect is correlated with algal reactive oxygen species levels, with significant enhancement in the presence of light and photosynthesis. Tryptoline inhibits algal photosynthesis by decreasing photosynthetic efficiency and carbon assimilation, inhibiting photochemical electron transfer, and increasing reaction centers and energy loss. Additionally, tryptoline inhibits electron transfer downstream of Q(A) in the photosynthetic process, leading to increased ROS generation.
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-v /F-m, PIABS, ETo/RC, and the expression of psaB and psbA genes related to photosynthesis, while increasing V-j and DIo/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 dosed reaction centers and energy loss. Moreover, following partial blockade of the photosynthetic electron transfer from Q(A) to Q(B) by diuron (3-(3-4-dichlorophenyI)-1,1-dimethylurea), the ROS of algae exposed to tryptoline is significantly decreased. Thus, tryptoline inhibits electron transfer downstream of Q(A), 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. (C) 2021 Published by Elsevier B.V.
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