title: Production of a biopolymer flocculant from Bacillus licheniformis and its flocculation properties.
abstract: Bacillus licheniformis CCRC 12826 produced extracellularly an excellent biopolymer flocculant in a large amount when it was grown aerobically in a culture medium containing citric acid, glutamic acid and glycerol as carbon sources. The biopolymer flocculant was an extremely viscous material with a molecular weight over 2 x 10(6) by gel permeation chromatography. It could be easily purified from the culture medium by ethanol precipitation. It was shown to be a homopolymer of glutamic acid by amino acid analysis and thin layer chromatography and presumed to be poly-glutamic acid (PGA). This bioflocculant efficiently flocculated various organic and inorganic suspensions. It flocculated a suspended kaolin suspension without cations, although its flocculating activity was synergistically stimulated by the addition of bivalent or trivalent cations Ca2+, Fe3+ and Al3+. However, the synergistic effects of metal cations were most effective at neutral pH ranges. The comparison of the flocculating activity between the present biopolymer and a commercial lower molecular weight product showed that the biopolymer of the present study had much higher activity. The high productivity and versatile applications of PGA make its development as a new biodegradable, harmless, biopolymer flocculant economical and advantageous.
authors.affiliation: Department of Environmental Engineering, Da-Yeh University, Taiwan, ROC. ils@aries.dyu.edu.tw
authors.forename: I L
authors.initials: IL
authors.lastname: Shih
authors.forename: Y T
authors.initials: YT
authors.lastname: Van
authors.forename: L C
authors.initials: LC
authors.lastname: Yeh
authors.forename: H G
authors.initials: HG
authors.lastname: Lin
authors.forename: Y N
authors.initials: YN
authors.lastname: Chang
mesh_terms: D000332:Aerobiosis; D001407:Bacillus / Q000254:growth & development / Q000378:metabolism*; D001704:Biopolymers / Q000096:biosynthesis* / Q000737:chemistry; D002850:Chromatography, Gel; D006863:Hydrogen-Ion Concentration; D011099:Polyglutamic Acid / Q000096:biosynthesis* / Q000737:chemistry; D014783:Viscosity
chemical_list: D001704:Biopolymers; D011099:Polyglutamic Acid