title: Extracellular polymeric substances facilitate the biosorption of phenanthrene on cyanobacteria Microcystis aeruginosa.
abstract: Phytoplankton-derived extracellular polymeric substances (EPS) are of vital importance for the biogeochemical cycles of hydrophobic organic pollutants in lake ecosystems. In this study, roles of loosely-bound EPS (LB-EPS) and tightly bound EPS (TB-EPS) in biosorption of phenanthrene (PHE) on a typical cyanobacteria Microcystis aeruginosa were investigated. The results showed that the biosorption of PHE on M. aeruginosa cell varied lasted 24 h, while the binding of PHE to LB-EPS and TB-EPS reached equilibrium within less than 2 h. The equilibrium biosorption capacities of M. aeruginosa cell, LB-EPS and TB-EPS were 6.78, 12.31, and 9.47 μg mg(-1), respectively, indicating that the binding of PHE to EPS was a considerable process involved in biosorption. Fluorescence quenching titration revealed that increasing temperature induced more binding sites in EPS for PHE and the binding process was driven by electrostatic force and hydrophobic interactions. Interestingly, dynamic and static quenching processes occurred simultaneously for the binding of PHE to protein-like substances in EPS, whereas the binding of PHE to humic-like substances belonged to static quenching. The relatively higher contents of proteins in LB-EPS produced a stronger binding capacity of PHE. Overall, the interactions between hydrophobic organic pollutants and cyanobacterial EPS are favorable to the bioaccumulation of hydrophobic organic pollutants in cyanobacteria and facilitate the regulatory function of cyanobacterial biomass as a biological pump.
authors: State Key Laboratory of Lake Science and Environment, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, Nanjing, 210008, PR China; Graduate University of Chinese Academy of Sciences, PR China.
authors: Leilei
authors: L
authors: Bai
authors: State Key Laboratory of Lake Science and Environment, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, Nanjing, 210008, PR China.
authors: Huacheng
authors: H
authors: Xu
authors: State Key Laboratory of Lake Science and Environment, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, Nanjing, 210008, PR China.
authors: Changhui
authors: C
authors: Wang
authors: State Key Laboratory of Lake Science and Environment, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, Nanjing, 210008, PR China.
authors: Jiancai
authors: J
authors: Deng
authors: State Key Laboratory of Lake Science and Environment, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, Nanjing, 210008, PR China. Electronic address: hljiang@niglas.ac.cn.
authors: Helong
authors: H
authors: Jiang
mesh_terms: D001673:Biodegradation, Environmental; D001704:Biopolymers / Q000378:metabolism*; D004785:Environmental Pollutants / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism*; D005110:Extracellular Space / Q000378:metabolism*; D057927:Hydrophobic and Hydrophilic Interactions; D060106:Lakes / Q000737:chemistry; D046931:Microcystis / Q000166:cytology* / Q000378:metabolism; D010616:Phenanthrenes / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism*; D012722:Sewage / Q000737:chemistry; D055672:Static Electricity
chemical_list: D001704:Biopolymers; D004785:Environmental Pollutants; D010616:Phenanthrenes; D012722:Sewage; C031181:phenanthrene
keywords: Biosorption; Cyanobacteria; Extracellular polymeric substances; Fluorescence quenching; Phenanthrene