title: Extraction and characterization of bound extracellular polymeric substances from cultured pure cyanobacterium (Microcystis wesenbergii).
abstract: Preliminary characterization of bound extracellular polymeric substances (bEPS) of cyanobacteria is crucial to obtain a better understanding of the formation mechanism of cyanobacterial bloom. However, the characterization of bEPS can be affected by extraction methods. Five sets (including the control) of bEPS from Microcystis extracted by different methods were characterized using three-dimensional excitation and emission matrix (3DEEM) fluorescence spectroscopy combined chemical spectrophotometry; and the characterization results of bEPS samples were further compared. The agents used for extraction were NaOH, pure water and phosphate buffered saline (PBS) containing cationic exchange resins, and hot water. Extraction methods affected the fluorescence signals and intensities in the bEPS. Five fluorescence peaks were observed in the excitation and emission matrix fluorescence spectra of bEPS samples. Two peaks (peaks T₁ and T₂) present in all extractions were identified as protein-like fluorophores, two (peaks A and C) as humic-like fluorophores, and one (peak E) as a fulvic-like substance. Among these substances, the humic-like and fulvic-like fluorescences were only seen in the bEPS extracted with hot water. Also, NaOH solution extraction could result in strong fluorescence intensities compared to the other extraction methods. It was suggested that NaOH at pH10.0 was the most appropriate method to extract bEPS from Microcystis. In addition, dialysis could affect the yields and characteristics of extracted bEPS during the determination process. These results will help us to explore the issues of cyanobacterial blooms.
authors.affiliation: State Key Laboratory of Lake Science and Environment, Nanjing Institute of Geography & Limnology, Chinese Academy of Sciences, Nanjing 210008, China. E-mail: qinbq@niglas.ac.cn; University of Chinese Academy of Sciences, Beijing 100049, China.
authors.forename: Lizhen
authors.initials: L
authors.lastname: Liu
authors.affiliation: State Key Laboratory of Lake Science and Environment, Nanjing Institute of Geography & Limnology, Chinese Academy of Sciences, Nanjing 210008, China. E-mail: qinbq@niglas.ac.cn. Electronic address: qinbq@niglas.ac.cn.
authors.forename: Boqiang
authors.initials: B
authors.lastname: Qin
authors.affiliation: State Key Laboratory of Lake Science and Environment, Nanjing Institute of Geography & Limnology, Chinese Academy of Sciences, Nanjing 210008, China. E-mail: qinbq@niglas.ac.cn.
authors.forename: Yunlin
authors.initials: Y
authors.lastname: Zhang
authors.affiliation: State Key Laboratory of Lake Science and Environment, Nanjing Institute of Geography & Limnology, Chinese Academy of Sciences, Nanjing 210008, China. E-mail: qinbq@niglas.ac.cn.
authors.forename: Guangwei
authors.initials: G
authors.lastname: Zhu
authors.affiliation: State Key Laboratory of Lake Science and Environment, Nanjing Institute of Geography & Limnology, Chinese Academy of Sciences, Nanjing 210008, China. E-mail: qinbq@niglas.ac.cn.
authors.forename: Guang
authors.initials: G
authors.lastname: Gao
authors.affiliation: State Key Laboratory of Lake Science and Environment, Nanjing Institute of Geography & Limnology, Chinese Academy of Sciences, Nanjing 210008, China. E-mail: qinbq@niglas.ac.cn; University of Chinese Academy of Sciences, Beijing 100049, China.
authors.forename: Qi
authors.initials: Q
authors.lastname: Huang
authors.affiliation: School of Environment and Planning, Liaocheng University, Shandong 252059, China.
authors.forename: Xin
authors.initials: X
authors.lastname: Yao
mesh_terms: D005591:Chemical Fractionation; D046931:Microcystis / Q000737:chemistry* / Q000378:metabolism*; D011108:Polymers / Q000737:chemistry* / Q000378:metabolism*
chemical_list: D011108:Polymers
keywords: Bound extracellular polymeric substances (bEPS); Extraction; Fluorescence intensities; Microcystis; Three-dimensional excitation and emission matrix (3DEEM)