Li Jiping, Wang Ying, Xu Zijie, Wu Chenyang, Zhu Zixin, Lyu Xingsheng, Li Jingjing, Zhang Xingru, Wang Yan, Luo Yuming, Li Wei
School of Life Sciences, Huaiyin Normal University, Huai'an 223300, China.
Jiangsu Collaborative Innovation Center of Regional Modern Agriculture & Environmental Protection, Huaiyin Normal University, Huai'an 223300, China.
Plants (Basel). 2025 Sep 4;14(17):2774. doi: 10.3390/plants14172774.
The ecotoxicity induced by macrolides has attracted widespread attention, but their impacts on the nitrogen metabolism and symbiotic environmental bacteria of microalgae remain unclear. This study examined the effects of roxithromycin (ROX) on the growth, chlorophyll levels, and nitrogen metabolism of ; investigated the changes in the composition and functions of environmental bacterial communities; and finally, analyzed the relationship between microalgae and environmental bacteria. The results indicated that all concentrations of ROX (0.1, 0.25, and 1 mg/L) inhibited microalgae growth, but the inhibition rates gradually decreased after a certain exposure period. For instance, the inhibition rate in the 1 mg/L treatment group reached the highest value of 43.43% at 7 d, which then decreased to 18.93% at 21 d. Although the total chlorophyll content was slightly inhibited by 1 mg/L ROX, the Chl-a/Chl-b value increased between 3 and 21 d. The nitrate reductase activities in the three treatments were inhibited at 3 d, but gradually returned to normal levels and even exceeded that of the control group at 21 d. Under ROX treatment, the consumption of NO by microalgae corresponded to the nitrate reductase activity, with slower consumption in the early stage and no obvious difference from the control group in the later stage. Overall, the diversity of environmental bacteria did not undergo significant changes, but the abundance of some specific bacteria increased, such as nitrogen-fixing bacteria ( and ) and organic contaminant-degrading bacteria (, , and ). The 0.25 and 1 mg/L ROX treatments significantly enhanced the carbohydrate metabolism, cofactor and vitamin metabolism, amino acid metabolism, and energy metabolism of the environmental bacteria, but significantly downregulated nitrogen denitrification. This study provides new insights into the environmental bacteria-driven recovery mechanism of microalgae under antibiotic stress.
大环内酯类抗生素引起的生态毒性已受到广泛关注，但其对微藻氮代谢及共生环境细菌的影响仍不明确。本研究检测了罗红霉素（ROX）对微藻生长、叶绿素水平和氮代谢的影响；研究了环境细菌群落组成和功能的变化；最后，分析了微藻与环境细菌之间的关系。结果表明，所有浓度的ROX（0.1、0.25和1mg/L）均抑制微藻生长，但在一定暴露期后抑制率逐渐降低。例如，1mg/L处理组在7d时抑制率达到最高值43.43%，在21d时降至18.93%。虽然1mg/L ROX对总叶绿素含量有轻微抑制作用，但在3至21d期间Chl-a/Chl-b值升高。三种处理中的硝酸还原酶活性在3d时受到抑制，但逐渐恢复到正常水平，甚至在21d时超过对照组。在ROX处理下，微藻对NO的消耗与硝酸还原酶活性相对应，前期消耗较慢，后期与对照组无明显差异。总体而言，环境细菌的多样性没有发生显著变化，但一些特定细菌的丰度增加，如固氮菌（和）以及有机污染物降解菌（、和）。0.25和1mg/L ROX处理显著增强了环境细菌的碳水化合物代谢、辅因子和维生素代谢、氨基酸代谢以及能量代谢，但显著下调了氮的反硝化作用。本研究为抗生素胁迫下环境细菌驱动的微藻恢复机制提供了新的见解。
