Effect of algicidal compound Nω-acetylhistamine on physiological response and algal toxins in Heterosigma akashiwo

• Published in: Ecotoxicology and environmental safety 2021-01, Vol.208, p.111423, Article 111423
• Main Authors: Zhu, Qiuyin, Wu, Biyu, Zhao, Ling
• Format: Article
• Language: English
• Subjects: Bacillus; Bacteria; Chlorophyll A; Dinoflagellida; Disinfectants - toxicity; Ecosystem; Genotoxicity; Harmful Algal Bloom; Hemolytic toxicity; HepG2 cell; Humans; Malondialdehyde; Marine Toxins - analysis; Oxidative stress; Stramenopiles - drug effects
• ISSN: 0147-6513; 1090-2414
• DOI: 10.1016/j.ecoenv.2020.111423

The toxic alga Heterosigma akashiwo (Raphidophyceae) is known to form harmful algal blooms (HABs), which can have serious negative effects on the aquatic ecosystem and human life. Previous study has shown that Nω-acetylhistamine (N-AcH), an algicidal compound secreted by algicidal bacteria Bacillus sp. Strain B1, can inhibit the growth of H. akashiwo. In this study, the algicidal mechanism of N-AcH against H. akashiwo was explored, and the changes of toxicity of H. akashiwo treated with N-AcH were investigated. The algal inhibition rate was calculated by the optical density method, and the results showed that the growth inhibition rate of H. akashiwo was about 90% when treated in the medium with 40 μg/mL N-AcH at 96 h. After 72 h treatment, transmission electron microscopy (TEM) showed that the microstructure of H. akashiwo cell was seriously damaged at this concentration. The content of Chlorophyll a and Chlorophyll b decreased while malonaldehyde levels increased, and superoxide dismutase activity first increased and then decreased as well as soluble protein content. GC-MS revealed that the type and content of fatty acids cut down after 48 h and 96 h treatment. Hemolytic test, MTT assay, and micronucleus test all demonstrated the decrease in the toxicity of H. akashiwo treated with 40 μg/mL N-AcH. In brief, N-AcH mainly kills H. akashiwo cell through oxidative stress and can also reduce its toxicity, so it is a promising algicide with the dual functions of killing algae and inhibiting algal toxic effects. •The growth of H.akashiwo is inhibited after being exposed to 0.5 μg/mL N-AcH for 96 h.•N-AcH induces ROS overproduction and destroys the integrity of H.akashiwo cells.•It can also reduce the toxic effects of algal toxins produced by H.akashiwo.•It is the first report that H.akashiwo has genotoxicity on HepG2 cells.