With the rapid changes in global climate and the frequent occurrence of regional extreme climates, the frequency and scale of the outbreak of filamentous cyanobacteria as the main type of bloom are increasing. These filamentous cyanobacteria not only release toxins, but also induce the formation of heteromorphic cells for nitrogen fixation in a low nitrogen environment. The contributing factors, duration and harm of the outbreak are more complex and diverse than Microcystis. However, most of the research focused on Microcystis blooms, and there are few studies on filamentous cyanobacteria.
Dr. Shenghua Zhang’s article entitled Physiological and morphological response of Aphanizomenon flos-aquae to watermelon (Citrullus lanatus) peel aqueous extract was published in Aquatic Toxicology. The article was supported by the National Natural Science Foundation Project.
In this study, the filamentous cyanobacteria Aphanizomenon flos-aquae was used as the tested algae. Based on the dual purpose of effectiveness and safety of biological materials for algae control and the waste recycling, the thesis studied the growth inhibitory effect of watermelon peel aqueous extract (WMPAE) on A. flos-aquae and the physiological response of A. flos-aquae. It provides some theoretical basis for the more effective use of agricultural waste watermelon peel to control algae in the future.
The results illustrated that (1) WMPAE has obvious inhibitory effect on A. flos-aquae. Exposure to different concentrations, the cell number and chlorophyll a content of A. flos-aquae showed a decreasing trend with time. Allelochemicals released from WMPAE decreased the cell viability promptly, causing the change of cell shape and damage of intracellular structure; (2) Due to the increase of malondialdehyde (MDA) content and the activation of antioxidant enzymes (SOD, CAT and POD), WMPAE caused excessive oxidative stress, and the cells suffered severe oxidative damage; (3) The photosynthetic pigment of A. flos-aquae first increased and then decreased. The chlorophyll fluorescence parameters Fv/Fm, Fv’/Fm’ and NPQ decreased significantly after 24 hours of exposure, and the photosynthesis of A. flos-aquae was significantly inhibited. It shows that WMPAE has some unfavorable biochemical and physiological effects on A. flos-aquae.
Linkof the paper via:
https://www.sciencedirect.com/science/article/pii/S0166445X20302988?via%3Dihub
