Previous Article | Next Article ![]()
Applied and Environmental Microbiology, August 1998, p. 3004-3008, Vol. 64, No. 8
Department of Microbiology and Molecular
Genetics1 and
Department of Chemical
Engineering,2 University of California, Los
Angeles, California 90095-1489
Received 23 April 1998/Accepted 9 June 1998
Pyrobaculum aerophilum, a hyperthermophilic archaeon,
can respire either with low amounts of oxygen or anaerobically with nitrate as the electron acceptor. Under anaerobic growth conditions, nitrate is reduced via the denitrification pathway to molecular nitrogen. This study demonstrates that P. aerophilum
requires the metal oxyanion WO42
0099-2240/98/$04.00+0
Copyright © 1998, American Society for Microbiology. All rights reserved.
Effect of Tungstate on Nitrate Reduction by the Hyperthermophilic
Archaeon Pyrobaculum aerophilum
for its
anaerobic growth on yeast extract, peptone, and nitrate as carbon and
energy sources. The addition of 1 µM MoO42
did not replace WO42
for the growth of
P. aerophilum. However, cell growth was completely inhibited by the addition of 100 µM MoO42
to the culture medium. At lower tungstate concentrations (0.3 µM and
less), nitrite was accumulated in the culture medium. The accumulation
of nitrite was abolished at higher WO42
concentrations (<0.7 µM). High-temperature enzyme assays for the
nitrate, nitrite, and nitric oxide reductases were performed. The
majority of all three denitrification pathway enzyme activities was
localized to the cytoplasmic membrane, suggesting their involvement in
the energy metabolism of the cell. While nitrite and nitric oxide
specific activities were relatively constant at different tungstate concentrations, the activity of nitrate reductase
was decreased fourfold at WO42
levels of 0.7 µM or higher. The high specific activity of the nitrate reductase
enzyme observed at low WO42
levels (0.3 µM
or less) coincided with the accumulation of nitrite in the culture
medium. This study documents the first example of the effect of
tungstate on the denitrification process of an extremely thermophilic
archaeon. We demonstrate here that nitrate reductase synthesis in
P. aerophilum occurs in the presence of high concentrations
of tungstate.
*
Corresponding author. Mailing address: Department of
Microbiology and Molecular Genetics, 1602 Molecular Sciences Building, University of California, Los Angeles, CA 90095-1489. Phone: (310) 825-8085. Fax: (310) 206-5231. E-mail:
imkes{at}microbio.ucla.edu.
This article has been cited by other articles:
Copyright © 2009 by the American Society for Microbiology. For an alternate route to Journals.ASM.org, visit: http://intl-journals.asm.org | More Info»