title: Bioremediation of Cr(VI) and immobilization as Cr(III) by Ochrobactrum anthropi.
abstract: Bioremediation of Cr(VI) through reduction relies on the notion that the produced Cr(III) may be precipitated or efficiently immobilized. However, recent reports suggest that soluble organo-Cr(III) complexes are present in various chromate-reducing bacterial systems. This work was designed to explore the factors that affect the immobilization of Cr(III) in the Ochrobactrum anthropi system. X-ray absorption fine structure analysis on the cell debris clearly verified that coordination of Cr(III) occurs on the surfaces via the chelating coordination with carboxyl- and amido-functional groups. However, competitive coordination experiments of Cr(III) revealed that the small molecules such as amino acids and their derivatives or multicarboxyl compounds hold stronger coordination ability with Cr(III) than with cell debris. We speculate that it is the preferential coordination of Cr(III) to the soluble organic molecules in the bacterial culture medium that inhibits effective immobilization of Cr(III) on the cells. On the basis of this understanding, a strategy with two-step control of the medium was proposed, and this achieved successful immobilization of Cr(VI) as Cr(III) by O. anthropi and Planococcus citreus in 5-50 L pilot-scale experiments.
authors.affiliation: State Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fujian 350002, China.
authors.forename: Yangjian
authors.initials: Y
authors.lastname: Cheng
authors.forename: Fenbo
authors.initials: F
authors.lastname: Yan
authors.forename: Feng
authors.initials: F
authors.lastname: Huang
authors.forename: Wangsheng
authors.initials: W
authors.lastname: Chu
authors.forename: Danmei
authors.initials: D
authors.lastname: Pan
authors.forename: Zhi
authors.initials: Z
authors.lastname: Chen
authors.forename: Jinsheng
authors.initials: J
authors.lastname: Zheng
authors.forename: Meijuan
authors.initials: M
authors.lastname: Yu
authors.forename: Zhang
authors.initials: Z
authors.lastname: Lin
authors.forename: Ziyu
authors.initials: Z
authors.lastname: Wu
mesh_terms: D001673:Biodegradation, Environmental; D002857:Chromium / Q000378:metabolism*; D020621:Ochrobactrum anthropi / Q000166:cytology / Q000254:growth & development / Q000378:metabolism*; D010084:Oxidation-Reduction; D010865:Pilot Projects; D013997:Time Factors; D014874:Water Pollutants, Chemical / Q000302:isolation & purification; D018508:Water Purification; D056928:X-Ray Absorption Spectroscopy
chemical_list: D014874:Water Pollutants, Chemical; D002857:Chromium