title: Production, characterization, and flocculation mechanism of cation independent, pH tolerant, and thermally stable bioflocculant from Enterobacter sp. ETH-2.
abstract: Synthetic high polymer flocculants, frequently utilized for flocculating efficiency and low cost, recently have been discovered as producing increased risk to human health and the environment. Development of a more efficient and environmentally sound alternative flocculant agent is investigated in this paper. Bioflocculants are produced by microorganisms and may exhibit a high rate of flocculation activity. The bioflocculant ETH-2, with high flocculating activity (2849 mg Kaolin particle/mg ETH-2), produced by strain Enterobacter sp. isolated from activated sludge, was systematically investigated with regard to its production, characterization, and flocculation mechanism. Analyses of microscopic observation, zeta potential and ETH-2 structure demonstrates the bridging mechanism, as opposed to charge neutralization, was responsible for flocculation of the ETH-2. ETH-2 retains high molecular weight (603 to 1820 kDa) and multi-functional groups (hydroxyl, amide and carboxyl) that contributed to flocculation. Polysaccharides mainly composed of mannose, glucose, and galactose, with a molar ratio of 1:2.9:9.8 were identified as the active constituents in bioflocculant. The structure of the long backbone with active sites of polysaccharides was determined as a primary basis for the high flocculation activity. Bioflocculant ETH-2 is cation independent, pH tolerant, and thermally stable, suggesting a potential fit for industrial application.
authors.affiliation: Research Center of Environmental Microbiology and Ecology, Chongqing Institute of Green and Intelligent Technology, Chinese Academy of Science, Chongqing, 400714, China.
authors.forename: Wei
authors.initials: W
authors.lastname: Tang
authors.affiliation: Research Center of Environmental Microbiology and Ecology, Chongqing Institute of Green and Intelligent Technology, Chinese Academy of Science, Chongqing, 400714, China; Key Laboratory of Reservoir Aquatic Environment, Chinese Academy of Sciences, Chongqing Institute of Green and Intelligent Technology, Chinese Academy of Sciences, Chongqing, 400714, China.
authors.forename: Liyan
authors.initials: L
authors.lastname: Song
authors.affiliation: Research Center of Environmental Microbiology and Ecology, Chongqing Institute of Green and Intelligent Technology, Chinese Academy of Science, Chongqing, 400714, China; Key Laboratory of Reservoir Aquatic Environment, Chinese Academy of Sciences, Chongqing Institute of Green and Intelligent Technology, Chinese Academy of Sciences, Chongqing, 400714, China.
authors.forename: Dou
authors.initials: D
authors.lastname: Li
authors.affiliation: Research Center of Environmental Microbiology and Ecology, Chongqing Institute of Green and Intelligent Technology, Chinese Academy of Science, Chongqing, 400714, China.
authors.forename: Jing
authors.initials: J
authors.lastname: Qiao
authors.affiliation: School of Chemistry and Chemical Engineering, Chongqing University of Technology, Chongqing, 400054, China.
authors.forename: Tiantao
authors.initials: T
authors.lastname: Zhao
authors.affiliation: Ministry of Education, Key Lab of Environmental Remediation and Ecosystem Health, College of Environmental and Resource Science, Zhejiang University, Hangzhou, 310058, China.
authors.forename: Heping
authors.initials: H
authors.lastname: Zhao
mesh_terms: D002412:Cations / Q000494:pharmacology*; D002849:Chromatography, Gas; D004754:Enterobacter / Q000302:isolation & purification* / Q000502:physiology*; D005427:Flocculation / Q000187:drug effects*; D005690:Galactose / Q000378:metabolism; D005947:Glucose / Q000378:metabolism; D006801:Humans; D006863:Hydrogen-Ion Concentration; D008358:Mannose / Q000378:metabolism; D010802:Phylogeny; D013696:Temperature
chemical_list: D002412:Cations; D005947:Glucose; D008358:Mannose; D005690:Galactose