Affiliation:
1. Institute of Ecology and Genetics, University of Aarhus, DK-8000 Aarhus C, Denmark
Abstract
The addition of 20 mM MoO
4
2−
(molybdate) to a reduced marine sediment completely inhibited the SO
4
2−
reduction activity by about 50 nmol g
−1
h
−1
(wet sediment). Acetate accumulated at a constant rate of about 25 nmol g
−1
h
−1
immediately after MoO
4
2−
addition and gave a measure of the preceding utilization rate of acetate by the SO
4
2−
-reducing bacteria. Similarly, propionate and butyrate (including isobutyrate) accumulated at constant rates of 3 to 7 and 2 to 4 nmol g
−1
h
−1
, respectively. The rate of H
2
accumulation was variable, and a range of 0 to 16 nmol g
−1
h
−1
was recorded. An immediate increase of the methanogenic activity by 2 to 3 nmol g
−1
h
−1
was apparently due to a release of the competition for H
2
by the absence of SO
4
2−
reduction. If propionate and butyrate were completely oxidized by the SO
4
2−
-reducing bacteria, the stoichiometry of the reactions would indicate that H
2
, acetate, propionate, and butyrate account for 5 to 10, 40 to 50, 10 to 20, and 10 to 20%, respectively, of the electron donors for the SO
4
2−
-reducing bacteria. If the oxidations were incomplete, however, the contributions by propionate and butyrate would only be 5 to 10% each, and the acetate could account for as much as two-thirds of the SO
4
2−
reduction. The presence of MoO
4
2−
seemed not to affect the fermentative and methanogenic activities; an MoO
4
2−
inhibition technique seems promising in the search for the natural substrates of SO
4
2−
reduction in sediments.
Publisher
American Society for Microbiology
Subject
Ecology,Applied Microbiology and Biotechnology,Food Science,Biotechnology
Cited by
287 articles.
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