Abstract：
Microalgae can promote antibiotic removal, which has attracted growing attention. However, its synergistic removal performance with bacteria in antibiotic pollutants is still poorly understood. In this study, firstly, we selected two green algae (Dictyosphaerium sp. and Chlorella sp.) and exposed them to Enrofloxacin (ENR) to observe their extracellular polysaccharides (EPS) concentration dynamic and the removal of antibiotics. Secondly, EPS was extracted and added to in situ lake water (no algae) to investigate its combined effect with bacteria. The results indicate that both Dictyosphaerium sp. and Chlorella sp. exhibited high tolerance to ENR stress. When the biomass of microalgae was low, ENR could significantly stimulate algae to produce EPS. The removal rates of Dictyosphaerium sp. and Chlorella sp. were 15.8% and 10.5%, respectively. The addition of EPS can both alter the microbial community structure in the lake water and promote the removal of ENR. The LEfSe analysis showed that there were significant differences in the microbial marker taxa, which promoted the increase of special functional bacteria for decomposing ENR, between the EPS-added group and the control group. The EPS of Dictyosphaerium sp. increased the abundance of Moraxellaceae and Spirosomaceae, while the EPS of Chlorella sp. increased the abundance of Sphingomonadaceae and Microbacteriaceae. Under the synergistic effect, Chlorella sp. achieved a maximum removal rate of 24.2%, while Dictyosphaerium sp. achieved a maximum removal rate of 28.9%. Our study provides new insights into the removal performance and mechanism of antibiotics by freshwater microalgae in water bodies and contribute to the development of more effective water treatment strategies.
摘要：
微藻可以促进抗生素去除，这引起了越来越多的关注。然而,其与细菌在抗生素污染物中的协同去除性能尚不清楚。在这项研究中,首先,我们选择了两种绿藻（Dictyosphaeriumsp。和小球藻sp。），并将其暴露于恩诺沙星（ENR）中，以观察其胞外多糖（EPS）的浓度动态和抗生素的去除。其次,提取EPS并将其添加到原位湖水（无藻类）中，以研究其与细菌的联合作用。结果表明，两种Dictyosphaeriumsp。和小球藻sp。表现出对ENR应力的高耐受性。当微藻的生物量较低时，ENR能显著刺激藻类产生EPS。Dictyospheriumsp.的去除率。和小球藻sp。分别为15.8%和10.5%，分别。EPS的添加既可以改变湖水中微生物群落结构，又可以促进ENR的去除。LEfSe分析表明,微生物标记类群存在显著差异,这促进了分解ENR的特殊功能细菌的增加，在EPS添加组和对照组之间。Dictyospheriumsp.的EPS。增加了桑兰科和螺旋体科的丰度，而小球藻的EPS。增加了Sphingomonadaceae和微生物科的丰度。在协同效应下,小球藻sp.最大去除率为24.2%，而Dictyosphaeriumsp.最大去除率为28.9%。我们的研究为淡水微藻在水体中对抗生素的去除性能和机理提供了新的见解，并有助于开发更有效的水处理策略。
