Archives of Microbiology

, Volume 161, Issue 2, pp 168–175

Formation of l-alanine as a reduced end product in carbohydrate fermentation by the hyperthermophilic archaeon Pyrococcus furiosus

  • Servé W. M. Kengen
  • Alfons J. M. Stams
Original Papers

DOI: 10.1007/BF00276479

Cite this article as:
Kengen, S.W.M. & Stams, A.J.M. Arch. Microbiol. (1994) 161: 168. doi:10.1007/BF00276479

Abstract

The hyperthermophilic archaeon Pyrococcus furiosus was found to form substantial amounts of l-alanine during batch growth on either cellobiose, maltose or pyruvate. Acetate, CO2 and H2 were produced next to alanine. The carbon- and electron balances were complete for all three substrates. Under standard growth conditions (N2/CO2 atmosphere) an alanine/acetate ratio of about 0.3 was found for either substrate. The alanine /acetate ratio was influenced, however, by the hydrogen partial pressure. In the presence of S0 or in coculture with Methanococcus jannaschii this ratio was only 0.07, whereas under a H2/CO2 atmosphere this ratio could amount up to 0.8. Alanine formation was also aflected by the NHinf4sup+concentration, i.e. below 4 mM, NHinf4sup+becomes limiting to alanine formation. Alanine formation was shown to occur via an alanine aminotransferase, which exhibited a specific activity in cell-free extract of up to 6.0 U/mg (90°C; direction of pyruvate formation). The alanine aminotransferase probably cooperates with glutamate dehydrogenase (up to 23 U/mg; 90°C) and ferredoxin: NADP+ oxidoreductase (up to 0.7 U/mg, using methyl viologen; 90°C) to recycle the electron acceptors involved in catabolism. Thus, the existence of this unusual alanine-forming branch enables P. furiosus to adjust its fermentation, depending on the redox potential of the terminal electron acceptor.

Key words

Pyrococcus furiosusHyperthermophileArchaeaFermentationl-alanineAlanine aminotransferaseGlutamate dehydrogenaseInterspecies hydrogen transfer

Abbreviations

DTT

dithiothreitol

MV

methyl viologen

AAT

alanine aminotransferase

GDH

glutamate dehydrogenase

MV: NADP+ OR

methyl viologen: NADP+ oxidoreductase

Copyright information

© Springer Verlag 1994

Authors and Affiliations

  • Servé W. M. Kengen
    • 1
  • Alfons J. M. Stams
    • 1
  1. 1.Department of MicrobiologyWageningen Agricultural UniversityWageningenThe Netherlands