The effect of plant extracts on growth and photosynthetic fluorescence characteristics of Microcystis flos-aquae

Abstract

<jats:title>Abstract</jats:title> <jats:p>The cyanobacteria Microcystis flos-aquae can cause harmful algal blooms in waterbodies, which threaten the normal functioning of aquatic ecosystems and human health. The plant extracts are considered as the promising algaecides. In this study, the effects of ten plant extracts (Cinnamomum camphora, Ginkgo biloba, Firmiana platanifolia, Salix babylonica, Euphorbia humifusa, Erigeron annuus, Solidago canadensis, Alternanthera philoxeroides, Thalia dealbata and Eichhornia crassipes) against M. flos-aquae were investigated. The results showed that all ten plant extracts had a significant inhibitory effect on M. flos-aquae growth after 96 h (P &amp;lt; 0.01). The inhibition rates of S. babylonica, E. humifusa, S. canadensis and A. philoxeroides were over 70.00%. Furthermore, the E. humifusa extract had the best inhibitory effect on the photosynthesis of M. flos-aquae, with the effective quantum yield of photosystem II (YII) and maximal relative electron transport rate (rETRmax) decreasing by 97.50% and 97.00%, respectively, after 96 h. Additionally, the E. humifusa extract was found to be nontoxic to non-target organisms such as Brachydanio rerio and Vallisneria spiralis within 96 h. This study contributes to the existing knowledge and data of freshwater cyanobacteria blooms, and provides insights for their control and the restoration of freshwater systems affected by cyanobacteria blooms.</jats:p>

Assessment of the Effects of Four Plant Species Used in Mexican Traditional Medicine Against Microcystis aeruginosa

“…In liquid medium, methanolic extracts of the four plant species possess statistically signi cant algaecidal activity against the toxic cyanobacterium M. aeruginosa. These results are similar to values obtained in some works such as that of Shi et al 2020, where they analyzed the effects of ten plant species on the growth of Microcystis os-aquae, reporting that all species showed signi cant inhibitory effects, with Alternanthera philoxeroides showing the highest degree of inhibition (77.30%), after 4 days of exposure to a concentration of 3 g/L. In another study published by Tazart et al, 2018, they observed that, aqueous extracts of Ranunculus aquatilis and Nasturtium o cinale showed inhibitions of 100 and 75% in M. aeruginosa positively correlating the polyphenols, avonoids and total tannins levels and the degree of inhibition of these species, similar to what was observed in our research with extracts of A. mexicana, B. spectabilis and L. tridentata.…”