College of Chemistry and Materials Science, Jinan University, Guangzhou, China.
School of Environment, Jinan University, Guangzhou, China.
Ecotoxicol Environ Saf. 2021 Jan 15;208:111423. doi: 10.1016/j.ecoenv.2020.111423. Epub 2020 Oct 16.
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.
塔玛亚历山大藻（红藻门）是一种产生有毒藻华（HABs）的藻类，会对水生态系统和人类生活产生严重的负面影响。先前的研究表明，Nω-乙酰组氨酸（N-AcH），一种由杀藻细菌芽孢杆菌菌株 B1 分泌的杀藻化合物，可以抑制塔玛亚历山大藻的生长。本研究探讨了 N-AcH 对塔玛亚历山大藻的杀藻机制，并研究了 N-AcH 处理后的塔玛亚历山大藻毒性变化。采用光密度法计算藻抑制率，结果表明，当培养基中 N-AcH 浓度为 40μg/mL 时，96h 后塔玛亚历山大藻的生长抑制率约为 90%。72h 处理后，透射电子显微镜（TEM）显示，在该浓度下，塔玛亚历山大藻细胞的微观结构严重受损。叶绿素 a 和叶绿素 b 的含量降低，丙二醛含量升高，超氧化物歧化酶活性先升高后降低，可溶性蛋白含量也降低。GC-MS 显示，48h 和 96h 处理后，脂肪酸的种类和含量减少。溶血试验、MTT 试验和微核试验均表明，40μg/mL N-AcH 处理后的塔玛亚历山大藻毒性降低。总之，N-AcH 主要通过氧化应激杀死塔玛亚历山大藻细胞，同时还可以降低其毒性，因此是一种具有杀藻和抑制藻毒双重功能的有前途的杀藻剂。
