SCNU Environmental Research Institute, Guangdong Provincial Key Laboratory of Chemical Pollution and Environmental Safety & MOE Key Laboratory of Theoretical Chemistry of Environment, South China Normal University, Guangzhou, 510006, China; School of Environment, South China Normal University, University Town, Guangzhou, 510006, China; State Key Laboratory of Organic Geochemistry, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou, 510640, China; University of Chinese Academy of Sciences, Beijing, 100049, China.
SCNU Environmental Research Institute, Guangdong Provincial Key Laboratory of Chemical Pollution and Environmental Safety & MOE Key Laboratory of Theoretical Chemistry of Environment, South China Normal University, Guangzhou, 510006, China; School of Environment, South China Normal University, University Town, Guangzhou, 510006, China.
Chemosphere. 2020 Aug;253:126722. doi: 10.1016/j.chemosphere.2020.126722. Epub 2020 Apr 8.
Levofloxacin (LEV) and sulfamethoxazole (SMX) are two extensively used antibiotics. Most investigations have been concentrated on the toxic effects of antibiotics on algal species evaluated with traditional ecotoxicological endpoints; however, limited information is available on the alterations in biomolecules induced by antibiotics. Here we investigated alterations in the structure and function of biomolecules to a model species Pseudokirchneriella subcapitata following exposure of LEV and SMX by applying Fourier transform infrared spectroscopy (FTIR). The growth inhibition tests revealed that both LEV and SMX had negative effects on algal growth, while SMX was found to be more toxic to P. subcapitata than LEV. Based on the FTIR analysis, alterations in the structure, composition and function of lipids and proteins were observed on microalgal cells, which were correlated with the dosage of LEV and SMX. As a result of lipid peroxidation induced by LEV and SMX, an increase in the lipid/protein ratio and decrease in the ratios of CH/lipid, CH/lipid, carbonyl ester/lipid and olefinic = CH/lipid were observed in all treatment groups with respect to the reference control. Moreover, alterations in the composition and secondary structure of proteins were also observed in accompany with a decrease in the Amide I/Amide II ratio and an increase of the loose β-sheet structure protein. LEV caused an elevated level of lipid peroxidation, while SMX induced a more obvious protein aggregation. The findings from this study showed that FTIR could reveal the toxic mechanism of these two antibiotics to algae at the biochemical level by linking alterations in biomolecules to biochemical dynamics and function.
左氧氟沙星（LEV）和磺胺甲恶唑（SMX）是两种广泛使用的抗生素。大多数研究都集中在抗生素对藻类物种的毒性影响上，这些研究采用了传统的生态毒理学终点进行评估；然而，关于抗生素引起的生物分子变化的信息有限。在这里，我们通过傅里叶变换红外光谱（FTIR）研究了 LEV 和 SMX 暴露后对模式物种假鱼腥藻（Pseudokirchneriella subcapitata）的生物分子结构和功能的改变。生长抑制试验表明，LEV 和 SMX 对藻类生长均有负面影响，而 SMX 对 P. subcapitata 的毒性大于 LEV。基于 FTIR 分析，观察到微藻细胞的脂质和蛋白质结构、组成和功能发生了变化，这些变化与 LEV 和 SMX 的剂量有关。由于 LEV 和 SMX 诱导的脂质过氧化，与对照相比，所有处理组的脂质/蛋白质比值增加，CH/脂质、CH/脂质、羰基酯/脂质和烯键=CH/脂质比值降低。此外，还观察到蛋白质组成和二级结构的变化，酰胺 I/酰胺 II 比值降低，疏松β-折叠结构蛋白质增加。LEV 导致脂质过氧化水平升高，而 SMX 诱导更明显的蛋白质聚集。本研究结果表明，FTIR 可以通过将生物分子的变化与生化动力学和功能联系起来，揭示这两种抗生素对藻类的毒性机制。
