The antibacterial agent Triclosan (TCS) is a ubiquitous environmental contaminant due to its widespread use. Sensitivity to TCS varies substantially among eu- and pro-karyotic species and its risk for the marine environment remains to be better elucidated. In particular, the effects that TCS causes on marine microbial communities are largely unknown. In this study we therefore used 16S amplicon rDNA sequencing to investigate TCS effects on the bacterial composition in marine periphyton communities that developed under long-term exposure to different TCS concentrations. Exposure to TCS resulted in clear changes in bacterial composition already at concentrations of 1 to 3.16 nM. We conclude that TCS affects the structure of the bacterial part of periphyton communities at concentrations that actually occur in the marine environment. Sensitive taxa, whose abundance decreased significantly with increasing TCS concentrations, include the Rhodobiaceae and Rhodobacteraceae families of Alphaproteobacteria, and unidentified members of the Candidate division Parcubacteria. Tolerant taxa, whose abundance increased significantly with higher TCS concentrations, include the families Erythrobacteraceae (Alphaproteobacteria), Flavobacteriaceae (Bacteroidetes), Bdellovibrionaceae (Deltaproteobacteria), several families of Gammaproteobacteria, and members of the Candidate phylum Gracilibacteria. Our results demonstrate the variability of TCS sensitivity among bacteria, and that TCS can change marine bacterial composition at concentrations that have been detected in the marine environment.

抗菌剂三氯生（TCS）由于其广泛用途而成为普遍存在的环境污染物。真核生物和原核生物对TCS的敏感性差异很大，其对海洋环境的风险仍有待进一步阐明。特别是，TCS对海洋微生物群落的影响在很大程度上尚不清楚。因此，在这项研究中，我们使用16S扩增子rDNA测序来研究TCS对长期暴露于不同TCS浓度下发育的海洋附生生物群落中细菌组成的影响。暴露于TCS会导致细菌成分在1至3.16 nM的浓度下发生明显变化。我们得出的结论是，TCS在海洋环境中实际发生的浓度下会影响周围植物群落细菌部分的结构。敏感的分类单元Rhodobiaceae和Rhodobacteraceae家族的Alphaproteobacteria和身份不明的成员候选部门Parcubacteria。宽容的类群，其丰度较高浓度的TCS增加显著，包括家庭Erythrobacteraceae（α-变形菌），黄杆菌（拟杆菌），Bdellovibrionaceae（δ-变形菌），几个家庭γ-变形菌候选门，以及成员Gracilibacteria。我们的结果证明了细菌之间TCS敏感性的差异，并且TCS可以在海洋环境中检测到的浓度下改变海洋细菌的组成。