title: A novel Fe(III) dependent bioflocculant from Klebsiella oxytoca GS-4-08: culture conditions optimization and flocculation mechanism.
abstract: In this work, the effect of cultivation factors on the flocculation efficiency (FE) of bioflocculant P-GS408 from Klebsiella oxytoca was optimized by the response surface methodology. The most significant factor, i.e. culture time, was determined by gray relational analysis. A total of 240 mg of purified P-GS408 was prepared from 1 liter of culture solution under the optimal conditions. GC-MS analysis results indicated that the polysaccharide of P-GS408 mainly contains Rhamnose and Galactose, and the existence of abundant hydroxyl, carboxyl and amino groups was evidenced by FTIR and XPS analyses. With the aid of Fe3+, the FE of kaolin solution by P-GS408 could achieve 99.48% in ten minutes. Functional groups of polysaccharide were involved in the first adsorption step and the zeta potential of kaolin solution changed from -39.0 mV to 43.4 mV in the presence of Fe3+and P-GS408. Three-dimensional excitation-emission (EEM) fluorescence spectra demonstrates that the trivalent Fe3+and Al3+can bind efficiently with P-GS408, while those univalent and divalent cations cannot. With the help of SEM images, FTIR, zeta potential and EEM spectra, we proposed the P-GS408 flocculation mechanism, which consists of coordination bond combination, charge neutrality, adsorption and bridging, and net catching.
authors.affiliation: College of Biology and the Environment, Co-Innovation Center for Sustainable Forestry in Southern China, Nanjing Forestry University, Nanjing, 210037 China.
authors.forename: Lei
authors.initials: L
authors.lastname: Yu
authors.affiliation: College of Biology and the Environment, Co-Innovation Center for Sustainable Forestry in Southern China, Nanjing Forestry University, Nanjing, 210037 China.
authors.forename: Qing-Wen
authors.initials: QW
authors.lastname: Tang
authors.affiliation: College of Biology and the Environment, Co-Innovation Center for Sustainable Forestry in Southern China, Nanjing Forestry University, Nanjing, 210037 China.
authors.forename: Yu-Jia
authors.initials: YJ
authors.lastname: Zhang
authors.affiliation: College of Biology and the Environment, Co-Innovation Center for Sustainable Forestry in Southern China, Nanjing Forestry University, Nanjing, 210037 China.
authors.forename: Rong-Ping
authors.initials: RP
authors.lastname: Chen
authors.affiliation: College of Biology and the Environment, Co-Innovation Center for Sustainable Forestry in Southern China, Nanjing Forestry University, Nanjing, 210037 China.
authors.forename: Xin
authors.initials: X
authors.lastname: Liu
authors.affiliation: College of Biology and the Environment, Co-Innovation Center for Sustainable Forestry in Southern China, Nanjing Forestry University, Nanjing, 210037 China.
authors.forename: Wei-Chuan
authors.initials: WC
authors.lastname: Qiao
authors.affiliation: CAS Key Laboratory of Urban Pollutant Conversion, Department of Chemistry, University of Science &Technology of China, Hefei, 230026 China.
authors.forename: Wen-Wei
authors.initials: WW
authors.lastname: Li
authors.affiliation: College of Biology and the Environment, Co-Innovation Center for Sustainable Forestry in Southern China, Nanjing Forestry University, Nanjing, 210037 China.
authors.forename: Hong-Hua
authors.initials: HH
authors.lastname: Ruan
authors.affiliation: Key Laboratory of Soil Environment and Pollution Remediation, Institute of Soil Science, Chinese Academy of Science, Nanjing 210008, China.
authors.forename: Xin
authors.initials: X
authors.lastname: Song
mesh_terms: D001431:Bacteriological Techniques; D003470:Culture Media; D005290:Ferric Compounds / Q000378:metabolism; D005427:Flocculation; D006863:Hydrogen-Ion Concentration; D007616:Kaolin; D041121:Klebsiella oxytoca / Q000254:growth & development / Q000378:metabolism*; D011135:Polysaccharides, Bacterial / Q000737:chemistry / Q000378:metabolism*; D013052:Spectrometry, X-Ray Emission; D017550:Spectroscopy, Fourier Transform Infrared; D013696:Temperature
chemical_list: D003470:Culture Media; D005290:Ferric Compounds; D011135:Polysaccharides, Bacterial; D007616:Kaolin