Chlorella vulgaris (C. vulgaris) and Raphidocelis subcapitata (R. subcapitata) are two model algal species applied for the testing of chemicals, whereas a considerable variation in their sensitivity to antibiotics has been reported. The difference in species sensitivity may be attributed to the xenobiotic-induced oxidative stress in algal cells. Thus, this study compared the responses of these two model green algae toward the exposure of erythromycin (ERY), a macrolide antibiotic, at the concentration levels of 0, 20, 40, 60 μg/L, and elucidated the toxic mechanism of action from the point of oxidative damage and antioxidant defense. To achieve this, effects on the endpoints of algal growth, malondialdehyde (MDA), antioxidants (superoxide dismutase [SOD], catalase [CAT], glutathione peroxidase [GP], glutathione, and glutathione S-transferase), and photosynthetic pigment contents were evaluated. After exposing for seven days, the growth of R. subcapitata was significantly stimulated at ERY 20 μg/L but inhibited at the higher exposure level of 60 μg/L. Contrarily, hormesis in C. vulgaris exposed to all ERY treatments was detected. With the increase in ERY exposure, MDA content, and the antioxidant activity of SOD, CAT, GP in R. subcapitata were gradually enhanced. In C. vulgaris, a declining trend in the MDA content and the activity of SOD, CAT, and GP was detected. These results provide insights into the ERY-altered production of reactive oxygen species and the antioxidant responses in two algae.

中文翻译：

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暴露于红霉素的两种绿藻物种的生长抑制和氧化应激

普通小球藻( C. vulgaris ) 和Raphidocelis subcapitata ( R. subcapitata) 是用于测试化学品的两种模型藻类物种，而据报道，它们对抗生素的敏感性存在相当大的差异。物种敏感性的差异可能归因于藻类细胞中异生物质诱导的氧化应激。因此，本研究比较了这两种模式绿藻对大环内酯类抗生素红霉素 (ERY) 暴露在 0、20、40、60 μg/L 浓度水平下的反应，并阐明了红霉素 (ERY) 的毒性作用机制。氧化损伤和抗氧化防御的点。为此，对藻类生长终点、丙二醛 (MDA)、抗氧化剂（超氧化物歧化酶 [SOD]、过氧化氢酶 [CAT]、谷胱甘肽过氧化物酶 [GP]、谷胱甘肽和谷胱甘肽 S-转移酶）和光合色素含量的影响是评估。R. subcapitata在 ERY 20 μg/L 时受到显着刺激，但在 60 μg/L 的较高暴露水平时受到抑制。相反，在暴露于所有 ERY 处理的C. vulgaris中检测到兴奋作用。随着增加ERY曝光，MDA含量，SOD，CAT的抗氧化活性，GP在R. subcapitata逐渐增强。在C. vulgaris 中，检测到MDA 含量和SOD、CAT 和GP 活性呈下降趋势。这些结果提供了对 ERY 改变的活性氧的产生和两种藻类的抗氧化反应的见解。