National School of Engineer of Sfax, Soukra Km 3.5 B.P. 1173-3038 Sfax,Tunisia.
Interdisciplinary Centre of Marine and Environmental Research, University of Porto, Terminal de Cruzeiros do Porto de Leixões, Avenida General Norton de Matos s/n, 4450-208 Matosinhos, Portugal; Institute of Biomedical Sciences Abel Salazar, University of Porto, Rua de Jorge Viterbo Ferreira 228, 4050-313 Porto, Portugal.
Sci Total Environ. 2019 Jan 15;648:962-972. doi: 10.1016/j.scitotenv.2018.08.193. Epub 2018 Aug 17.
This work investigated the potential of microbial communities native to an estuarine environment to biodegrade enrofloxacin (ENR) and oxytetracycline (OXY). Sediments collected from two sites in the Douro river estuary (Porto, Portugal) were used as inocula for the biodegradation experiments. Experiments were carried out for one month, during which ENR and OXY (1 mg L) were supplemented individually or in mixture to the cultures at 10-day intervals. Acetate (400 mg L) was added to the cultures every 3 days to support microbial growth. A series of experimental controls were established in parallel to determine the influence of abiotic breakdown and adsorption in the removal of the antibiotics. Removal of antibiotics was followed by measuring their concentration in the culture medium. Additionally, next-generation sequencing of the 16S rRNA gene amplicon was employed to understand how microbial communities responded to the presence of the antibiotics. At the end of the biodegradation experiments, microbial cultures derived from the two estuarine sediments were able to remove up to 98% of ENR and over 95% of OXY. The mixture of antibiotics did not affect their removal. ENR was removed mainly by biodegradation, while abiotic mechanisms were found to have a higher influence in the removal of OXY. Both antibiotics adsorbed at different extents to the estuarine sediments used as inocula but exhibited a higher affinity to the sediment with finer texture and higher organic matter content. The presence of ENR and OXY in the culture media influenced the dynamics of the microbial communities, resulting in a lower microbial diversity and richness and in the predominance of bacterial species belonging to the phylum Proteobacteria. Therefore, microbial communities native from estuarine environments have potential to respond to the contamination caused by antibiotics and may be considered for the recovering of impacted environments through bioremediation.
本研究考察了河口环境中原生微生物群落对恩诺沙星（ENR）和土霉素（OXY）的生物降解潜力。从葡萄牙杜罗河口的两个地点采集沉积物作为生物降解实验的接种物。实验进行了一个月，在此期间，每隔 10 天向培养物中单独或混合补充 ENR 和 OXY（1mg/L）。每隔 3 天向培养物中添加乙酸盐（400mg/L）以支持微生物生长。同时建立了一系列实验对照，以确定非生物降解和吸附对去除抗生素的影响。通过测量培养基中抗生素的浓度来跟踪抗生素的去除情况。此外，还采用 16S rRNA 基因扩增子的高通量测序来了解微生物群落对抗生素存在的反应。在生物降解实验结束时，从两个河口沉积物中获得的微生物培养物能够去除高达 98%的 ENR 和超过 95%的 OXY。抗生素混合物的存在并不影响它们的去除。ENR 主要通过生物降解去除，而发现非生物机制对 OXY 的去除有更高的影响。两种抗生素在不同程度上吸附到用作接种物的河口沉积物上，但对质地较细和有机物含量较高的沉积物的亲和力更高。ENR 和 OXY 在培养基中的存在影响了微生物群落的动态，导致微生物多样性和丰富度降低，并且优势细菌物种属于变形菌门。因此，来自河口环境的微生物群落有可能对抗生素污染作出反应，并可通过生物修复来考虑恢复受影响的环境。
