Mechanisms of the novel pesticide sodium dodecyl benzene sulfonate in the mitigation of protozoan ciliated pathogens during microalgal cultivation.

Protozoan ciliates represent a common biological contaminant during microalgae cultivation, which will lead to a decline in microalgae productivity. This study investigated the effectiveness of sodium dodecyl benzene sulfonate (SDBS) in controlling ciliate populations within microalgae cultures. SDBS concentrations of 160 mg/L and 100 mg/L were found to effectively manage the representative species of ciliates contamination by Euplotes vannus and Uronema marinum during the cultivation of Synechococcus and Chlorella, and the growth vitality of microalgae has been restored. Additionally, SDBS at these concentrations reduced oxidative stress resistance and induced membrane damage to remove biological pollutants by modulating enzyme activity, affecting lipid, energy, amino acid metabolism pathways, and processes such as translation and protein folding. This research provides insights into the mechanisms through which SDBS effectively combats protozoan ciliates during the microalgal cultivation. This contributes to reduce biological pollution, ensure the overall productivity and healthy and sustainable management of microalgae ecosystems.

Toxic effects on ciliates under nano-/micro-plastics coexist with silver nanoparticles.

Owing to the degradation of plastics, microplastics (MPs) and nanoplastics (NPs) have remained the focus of global attention. Silver nanoparticles (AgNPs) could adversely affect marine organisms due to their broad application. So far, the combined effects of MPs/NPs (strong adsorbents) with AgNPs on marine organisms are scant. Thus, four sizes polystyrene beads (80 nm, 220 nm, 1.07 µm, and 2.14 µm) combined with AgNPs (30 nm) were assessed using ciliated protozoa Uronema marinum. Results showed that MPs/NPs dramatically decrease the abundance, biovolume, and carbon biomass of U. marinum. And, exposure could cause changes of antioxidant enzyme activity and antioxidant content on U. marinum. The combined toxicity of MPs/NPs with AgNPs to ciliates showed an enhanced effect compared to exposure alone. Additionally, the negative effects under exposure of NPs plus AgNPs were more significant than those of MPs plus AgNPs. Transcriptome sequencing showed that co-exposure could affect the energy metabolism and lipid metabolism of ciliates, even cause DNA and protein damage. Our study provided a novel insight and first-hand basic data for the understanding of combined toxicity of MPs /NPs with AgNPs on the basic trophic level ciliated protozoa in marine ecosystems.