Roxithromycin (ROX) has received increasing concern due to its large usage, ubiquitous detection in environment and high ecotoxicology risk. This study investigated the acute and chronic effects of ROX on the growth, chlorophyll, antioxidant enzymes, and malonaldehyde (MDA) content of Chlorella pyrenoidosa, as well as the removal mechanism of ROX during microalgae cultivation. The calculated 96 h median effective concentration of ROX on yield (EyC50) and specific growth rate (ErC50) of C. pyrenoidosa was 0.81 and 2.87 mg/L, respectively. After 96 h exposure, 1.0 ~ 2.0 mg/L of ROX significantly inhibited the synthesis of chlorophyll and promoted the activities of SOD and CAT (p < 0.05). The MDA content increased with the ROX concentration increasing from 0.5 ~ 1.0 mg/L, and then decreased to 105.76% of the control exposure to 2.0 mg/L ROX, demonstrating the oxidative damage could be moderated by the upregulation of SOD and CAT activities. During the 21 d chronic exposure, low concentration of ROX (0.1 and 0.25 mg/L) showed no significant effect on the growth and chlorophyll content of algae during the first 14 d, but significantly inhibited the growth of algae and the synthesis of chlorophyll at 21 d (p < 0.05 or p < 0.01). 1.0 mg/L ROX significantly inhibited the growth of microalgae during 3 ~ 21 d and the synthesis of chlorophyll at 7 ~ 21 d. High concentration and long-term exposure of low concentration of ROX caused the SOD and CAT activities and MDA content to increase, demonstrating a higher level of oxidative damage of microalgae. During the first 14 d, abiotic removal of ROX played a more important role, contributing about 12.21% ~ 21.37% of ROX removal. After 14 d, the biodegradation of ROX by C. pyrenoidosa gradually became a more important removal mechanism, contributing about 45.99% ~ 53.30% of ROX removal at 21 d. Bio-adsorption and bioaccumulation both played minor roles in the removal of ROX during algae cultivation.

中文翻译：

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罗红霉素和淡水微藻，小球藻小球藻的相互作用：毒性和清除机制。

罗红霉素（ROX）由于其使用量大，在环境中无处不在的检测以及较高的生态毒理学风险而受到越来越多的关注。本研究调查了ROX对小球藻的生长，叶绿素，抗氧化酶和丙二醛（MDA）含量的急性和慢性影响，以及ROX在微藻培养过程中的去除机理。计算得出的96小时ROX的平均有效浓度为0.81和2.87 mg / L，这是对吡虫假单胞菌的产量（EyC50）和比生长速率（ErC50）的影响。暴露96 h后，1.0〜2.0 mg / L的ROX显着抑制叶绿素的合成并促进SOD和CAT的活性（p <0.05）。随着ROX浓度从0.5〜1.0 mg / L增加，MDA含量增加，然后降至2.0 mg / L ROX的对照暴露的105.76％，证明SOD和CAT活性上调可以减轻氧化损伤。在21 d的长期暴露过程中，低浓度的ROX（0.1和0.25 mg / L）在开始的14 d内对藻类的生长和叶绿素含量没有明显影响，但显着地抑制了藻类的生长和叶绿素的合成。 21 d（p <0.05或p <0.01）。1.0 mg / L ROX在3〜21 d显着抑制微藻的生长，在7〜21 d抑制叶绿素的合成。高浓度和低浓度ROX的长期暴露导致SOD和CAT活性以及MDA含量增加，表明微藻的氧化损伤水平更高。在最初的14 d中，非生物去除ROX发挥了更重要的作用，占ROX去除的大约12.21％〜21.37％。14天后，C.pyrenoidosa对ROX的生物降解逐渐成为更重要的去除机理，在21 d时约占ROX去除量的45.99％〜53.30％。在藻类培养过程中，生物吸附和生物富集在去除ROX方面均起着较小的作用。