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Hydrogen thresholds and steady-state concentrations associated with microbial arsenate respiration

H2 thresholds for microbial respiration of arsenate (As(V)) were investigated in a pure culture of Sulfurospirillum arsenophilum. H2 was consumed to threshold concentrations of 0.03-0.09 nmol/L with As(V) as terminal electron acceptor, allowing for a Gibbs free-energy yield of 36-41 kJ per mol of reaction. These thresholds are among the lowest measured for anaerobic respirers and fall into the range of denitrifiers or Fe(III)-reducers. In sediments from an arsenic-contaminated aquifer in the Red River flood plain, Vietnam, H2 levels decreased to 0.4-2 nmol/L when As(V) was added under anoxic conditions. When As(V) was depleted, H2 concentrations rebounded by a factor of 10, a level similar to that observed in arsenic-free controls. The sediment-associated microbial population completely reduced millimolar levels of As(V) to arsenite (As(III)) within a few days. The rate of As(V)-reduction was essentially the same in sediments amended with a pure culture of S. arsenophilum. These findings together with a review of observed H2 threshold and steady-state values suggest that microbial As(V)-respirers have a competitive advantage over several other anaerobic respirers through their ability to thrive at low H2 levels. © 2007 American Chemical Society.

 Heimann A.C., Blodau C., Postma D., Larsen F., Viet P.H., Nhan P.Q., Jessen S., Duc M.T., Hue N.T.M., Jakobsen R.
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  Từ khóa : Arsenic compounds; Concentration (process); Electrons; Hydrogen; Microorganisms; Sediments; Anaerobic respirers; Electron acceptor; Pollution control; arsenic acid; hydrogen; Arsenic compounds; Concentration (process); Electrons; Hydrogen; Microorganisms; Pollution control; Sediments; anoxic conditions; aquifer pollution; arsenate; floodplain; Gibbs free energy; hydrogen; microbial community; respiration; river; steady-state equilibrium; threshold; anoxia; aquifer; article; concentration (parameters); microbial respiration; nonhuman; reduction kinetics; Spirillum; steady state; Sulfurospirillum arsenophilum; Arsenates; Biodegradation, Environmental; Chromatography, Gas; Environmental Pollutants; Epsilonproteobacteria; Geologic Sediments; Hydrogen; Methane; Thermodynamics; Vietnam; Asia; Eurasia; Red River [Asia]; Southeast Asia; Viet Nam; Sulfurospirillum arsenophilum