Previous Article | Next Article ![]()
Appl Environ Microbiol, July 1998, p. 2485-2489, Vol. 64, No. 7
Centre de Bioingénierie Gilbert Durand,
UMR CNRS, L. A. INRA, Institut National des Sciences
Appliquées, Complexe Scientifique de Rangueil, F-31077 Toulouse
Cedex 4, France
Received 4 November 1997/Accepted 29 April 1998
Unlike other lactic acid bacteria, Lactococcus lactis
subsp. lactis NCDO 2118 was able to grow in a medium
lacking glutamate and the amino acids of the glutamate family. Growth
in such a medium proceeded after a lag phase of about 2 days and with a reduced growth rate (0.11 h
0099-2240/98/$04.00+0
Copyright © 1998, American Society for Microbiology. All rights reserved.
Glutamate Biosynthesis in Lactococcus
lactis subsp. lactis NCDO 2118
1) compared to that in the
reference medium containing glutamate (0.16 h
1). The
enzymatic studies showed that a phosphoenolpyruvate carboxylase activity was present, while the malic enzyme and the enzymes of the
glyoxylic shunt were not detected. As in most anaerobic bacteria, no
-ketoglutarate dehydrogenase activity could be detected, and the
citric acid cycle was restricted to a reductive pathway leading to
succinate formation and an oxidative branch enabling the synthesis of
-ketoglutarate. The metabolic bottleneck responsible for the limited
growth rate was located in this latter pathway. As regards the
synthesis of glutamate from
-ketoglutarate, no glutamate dehydrogenase was detected. While the glutamate
synthase-glutamine synthetase system was detected at a low level, high
transaminase activity was measured. The conversion of
-ketoglutarate
to glutamate by the transaminase, the reverse of the normal
physiological direction, operated with different amino acids as
nitrogen donor. All of the enzymes assayed were shown to be
constitutive.
*
Corresponding author. Mailing address: INSA,
Département de Génie Biochimique et Alimentaire, Complexe
Scientifique de Rangueil, F-31077 Toulouse Cedex, France. Phone:
(33) 5 61 55 94 38. Fax: (33) 5 61 55 94 02. E-mail:
loubiere{at}insa-tlse.fr.
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»