X Wu et al./Warer Research 165 (2019)114975 4.Conclusions 2 0-L An A an OTU d ARG subtypes ial hosts we in rive biofilms path dRC,2010 magnitude faster than BLASt ransfer o tal hehs for a mon dels Nat.Rev function of these anthropogenic particles in the freshwater KL Re rure:and ampotngpeedaigper tream MS Declaration of Competing Interest Acknowledgement心 iang.L.Hu> tion Committee )The authors are th 11810-1 Appendix A.Supplementary data nez,K.C be found References of bronchiectasis by Pseud r.S.K..Schloss,PD.,2013.Deve Alien.HK. ettle ikas.B..Boyd.G.D.Me e.R.R e in 9. M Zhang.H.Alv PJJ.2011.0 nic aggrega Bole AM-Lohse.M.Usadel.2014. -2433 50(4. Conclusions Microplastics provide a unique microhabitat that supports the growth of specific bacterial consortia. Microplastic biofilms have a distinctive microbial community structure compared with biofilms formed on natural substrates, as verified by taxon composition, community separation pattern (PCoA analysis), OTUs with signifi- cantly different abundance, and network relationships. Specific ARG subtypes and several pathogenic bacterial hosts were also selectively enriched by microplastic biofilm. Microplastics could be viewed as a novel, functionally important microhabitat in rivers and the dispersal of the microorganisms present within micro￾plastic biofilms, especially pathogenic microorganisms, may enhance the risks to human health. Further studies are therefore required to establish the mechanism of horizontal gene transfer of ARGs via microplastic biofilms. This could pave the way for a more thorough understanding of the environmental behaviour and function of these anthropogenic particles in the freshwater ecosystem. Differences among the microplastic and biofilm and the natural particles have the potential to affect river environments in at least two ways: first, by introducing species into places where rock and leaf particles cannot reach and change the local community struc￾ture; and second, by transporting species (including specific path￾ogens) with tolerance to antibiotics downstream. Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper. Acknowledgements This study was supported by National Key Basic Research Development Program (2015CB459000), the National Natural Sci￾ence Foundation of China (No. 31670498) and the Science and Technology Innovation Committee of Shenzhen (No. JCYJ20170818091727570). The authors are thankful to Dr. Zongbao Liu's help in data analysis. Appendix A. 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