title: Long-term effects of CuO nanoparticles on the surface physicochemical properties of biofilms in a sequencing batch biofilm reactor.
abstract: In this study, we examined the long-term effects of copper oxide nanoparticles (CuO NPs) on the production and properties of EPS and the resulting variations in surface physicochemical characteristics of biofilms in a sequencing batch biofilm reactor. After exposure to 50 mg/L CuO NPs for 45 days, the protein (PRO) and polysaccharide (PS) contents in loosely bound EPS (LB-EPS) decreased as the production of LB-EPS decreased from 34.4 to 30 mg TOC/g EPS. However, the production of tightly bound EPS (TB-EPS) increased by 16.47 % as the PRO and PS contents increased. The content of humic-like substances (HS) increased significantly, becoming the predominant constituent in EPS with the presence of 50 mg/L CuO NPs. Furthermore, the results of three-dimensional excitation-emission fluorescence spectra confirmed the various changes in terms of the LB-EPS and TB-EPS contents after exposure to CuO NPs. Fourier transform infrared spectroscopy showed that the -OH and -NH2groups of proteins in EPS were involved in the reaction with CuO NPs. Moreover, the chronic exposure to CuO NPs induced a negative impact on the flocculating efficiency of EPS and on the hydrophobicity and aggregation ability of microbial cells. The PRO/PS ratios of different EPS fractions were consistent with their hydrophobicities (R2>0.98) and bioflocculating efficiencies (R2>0.95); however, there was no correlation with aggregation ability. Additionally, the presence of bovine serum albumin (BSA) prevented the physical contact between CuO NPs and EPS as a result of NP aggregation and electrostatic repulsion.
authors: Key Laboratory of Integrated Regulation and Resources Development on Shallow Lakes, Ministry of Education, Hohai University, Nanjing, 210098, People's Republic of China.|College of Environment, Hohai University, Nanjing, 210098, People's Republic of China.
authors: Jun
authors: J
authors: Hou
authors: Key Laboratory of Integrated Regulation and Resources Development on Shallow Lakes, Ministry of Education, Hohai University, Nanjing, 210098, People's Republic of China.|College of Environment, Hohai University, Nanjing, 210098, People's Republic of China.
authors: Guoxiang
authors: G
authors: You
authors: Key Laboratory of Integrated Regulation and Resources Development on Shallow Lakes, Ministry of Education, Hohai University, Nanjing, 210098, People's Republic of China.|College of Environment, Hohai University, Nanjing, 210098, People's Republic of China.
authors: Yi
authors: Y
authors: Xu
authors: Key Laboratory of Integrated Regulation and Resources Development on Shallow Lakes, Ministry of Education, Hohai University, Nanjing, 210098, People's Republic of China.|College of Environment, Hohai University, Nanjing, 210098, People's Republic of China.
authors: Chao
authors: C
authors: Wang
authors: Key Laboratory of Integrated Regulation and Resources Development on Shallow Lakes, Ministry of Education, Hohai University, Nanjing, 210098, People's Republic of China. pfwang2005@hhu.edu.cn.|College of Environment, Hohai University, Nanjing, 210098, People's Republic of China. pfwang2005@hhu.edu.cn.
authors: Peifang
authors: P
authors: Wang
authors: Key Laboratory of Integrated Regulation and Resources Development on Shallow Lakes, Ministry of Education, Hohai University, Nanjing, 210098, People's Republic of China. mlz1988@126.com.|College of Environment, Hohai University, Nanjing, 210098, People's Republic of China. mlz1988@126.com.
authors: Lingzhan
authors: L
authors: Miao
authors: Key Laboratory of Integrated Regulation and Resources Development on Shallow Lakes, Ministry of Education, Hohai University, Nanjing, 210098, People's Republic of China.|College of Environment, Hohai University, Nanjing, 210098, People's Republic of China.
authors: Yi
authors: Y
authors: Li
authors: Key Laboratory of Integrated Regulation and Resources Development on Shallow Lakes, Ministry of Education, Hohai University, Nanjing, 210098, People's Republic of China.|College of Environment, Hohai University, Nanjing, 210098, People's Republic of China.
authors: Yanhui
authors: Y
authors: Ao
authors: Key Laboratory of Integrated Regulation and Resources Development on Shallow Lakes, Ministry of Education, Hohai University, Nanjing, 210098, People's Republic of China.|College of Environment, Hohai University, Nanjing, 210098, People's Republic of China.
authors: Bowen
authors: B
authors: Lv
authors: Key Laboratory of Integrated Regulation and Resources Development on Shallow Lakes, Ministry of Education, Hohai University, Nanjing, 210098, People's Republic of China.|College of Environment, Hohai University, Nanjing, 210098, People's Republic of China.
authors: Yangyang
authors: Y
authors: Yang
mesh_terms: D018441:Biofilms / Q000187:drug effects*; D019149:Bioreactors / Q000382:microbiology*; D055598:Chemical Phenomena; D003300:Copper / Q000378:metabolism*; D053758:Nanoparticles / Q000378:metabolism*; D011134:Polysaccharides / Q000032:analysis; D011506:Proteins / Q000032:analysis; D013499:Surface Properties / Q000187:drug effects*
chemical_list: D011134:Polysaccharides; D011506:Proteins; D003300:Copper; C030973:cupric oxide
keywords: Biofilms; Bioflocculating efficiency; CuO nanoparticles; Extracellular polymeric substances; Microbial adhesion to hydrocarbons; Microbial cell aggregation