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Dissimilatory selenate reduction potentials in a diversity of sediment types

Applied and Environmental Microbiology

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Abstract

We measured potential rates of bacterial dissimilatory reduction of 75SeO42- to 75Se0 in a diversity of sediment types, with salinities ranging from freshwater (salinity = 1 g/liter) to hypersaline (salinity = 320 g/liter and with pH values ranging from 7.1 to 9.8. Significant biological selenate reduction occurred in all samples with salinities from 1 to 250 g/liter but not in samples with a salinity of 320 g/liter. Potential selenate reduction rates (25 nmol of SeO42- per ml of sediment added with isotope) ranged from 0.07 to 22 ??mol of SeO42- reduced liter-1 h-1. Activity followed Michaelis-Menten kinetics in relation to SeO42- concentration (K(m) of selenate = 7.9 to 720 ??M). There was no linear correlation between potential rates of SeO42- reduction and salinity, pH, concentrations of total Se, porosity, or organic carbon in the sediments. However, potential selenate reduction was correlated with apparent K(m) for selenate and with potential rates of denitrification (r = 0.92 and 0.81, respectively). NO3-, NO2-, MoO42-, and WO42- inhibited selenate reduction activity to different extents in sediments from both Hunter Drain and Massie Slough, Nev. Sulfate partially inhibited activity in sediment from freshwater (salinity = 1 g/liter) Massie Slough samples but not from the saline (salinity = 60 g/liter) Hunter Drain samples. We conclude that dissimilatory selenate reduction in sediments is widespread in nature. In addition, in situ selenate reduction is a first-order reaction, because the ambient concentrations of selenium oxyanions in the sediments were orders of magnitude less than their K(m)s.

Additional Publication Details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
Dissimilatory selenate reduction potentials in a diversity of sediment types
Series title:
Applied and Environmental Microbiology
Volume
56
Issue:
11
Year Published:
1990
Language:
English
Larger Work Type:
Article
Larger Work Subtype:
Journal Article
Larger Work Title:
Applied and Environmental Microbiology
First page:
3550
Last page:
3557
Number of Pages:
8