title: Microbial recovery of vanadium by the acidophilic bacterium, Acidocella aromatica.
abstract: OBJECTIVE
  To investigate the bioreduction of toxic pentavalent vanadium [vanadate; V(V)] in the acidophilic, Fe(III)-reducing obligately heterotrophic bacterium, Acidocella aromatica PFBC.
  
  
  RESULTS
  Although the initial lag-phase of growth became extended with increasing initial V(V) concentrations, the final cell density during aerobic growth of A. aromatica PFBC was unaffected by up to 2 mM V(V). While strain PFBC is an aerobe, growth-decoupled PFBC cell suspensions directly reduced V(V) using fructose, both micro-aerobically and anaerobically, under highly acidic (pH 2) and moderately acidic (pH 4.5) conditions. Bio reduced V(IV) was subsequently precipitated even under micro-aerobic conditions, mostly by encrusting the cell surface. An anaerobic condition at pH 4.5 was optimal for forming and maintaining stable V(IV)-precipitates. Recovery of approx. 70 % of V(V) from the solution phase was made possible with V(V) at 1 mM.
  
  
  CONCLUSIONS
  The first case of direct V(V) reducing ability and its subsequent V recovery from the solution phase was shown in acidophilic prokaryotes. Possible utilities of V(V) bioreduction in acidic conditions, are discussed.
authors.affiliation: Department of Earth Resources Engineering, Faculty of Engineering, Kyushu University, 744 Motooka, Nishi-Ku, Fukuoka, 819-0395, Japan. okibe@mine.kyushu-u.ac.jp.
authors.forename: Naoko
authors.initials: N
authors.lastname: Okibe
authors.affiliation: Department of Earth Resources Engineering, Faculty of Engineering, Kyushu University, 744 Motooka, Nishi-Ku, Fukuoka, 819-0395, Japan.
authors.forename: Masashi
authors.initials: M
authors.lastname: Maki
authors.affiliation: Department of Earth Resources Engineering, Faculty of Engineering, Kyushu University, 744 Motooka, Nishi-Ku, Fukuoka, 819-0395, Japan.
authors.forename: Daisuke
authors.initials: D
authors.lastname: Nakayama
authors.affiliation: Department of Earth Resources Engineering, Faculty of Engineering, Kyushu University, 744 Motooka, Nishi-Ku, Fukuoka, 819-0395, Japan.
authors.forename: Keiko
authors.initials: K
authors.lastname: Sasaki
mesh_terms: D016947:Acetobacteraceae / Q000378:metabolism; D001673:Biodegradation, Environmental; D005632:Fructose / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D014639:Vanadium / Q000378:metabolism*
chemical_list: D014639:Vanadium; D005632:Fructose
keywords: Acidocella aromatica; Acidophile; Bioreduction; Bioremediation; Iron-reducing bacteria; Vanadium