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Applied and Environmental Microbiology, September 2000, p. 3686-3691, Vol. 66, No. 9
Laboratory of Food Microbiology, Wageningen
University, Wageningen,1 and Microbial
Ingredients Section, NIZO Food Research,
Ede,2 The Netherlands
Received 24 January 2000/Accepted 8 June 2000
The effects of low-temperature stress on the glycolytic activity of
the lactic acid bacterium Lactococcus lactis were studied. The maximal glycolytic activity measured at 30°C increased
approximately 2.5-fold following a shift from 30 to 10°C for 4 h
in a process that required protein synthesis. Analysis of cold
adaptation of strains with genes involved in sugar metabolism disrupted
showed that both the phosphoenolpyruvate-dependent sugar
phosphotransferase system (PTS) subunit HPr and catabolite control
protein A (CcpA) are involved in the increased acidification at low
temperatures. In contrast, a strain with the PTS subunit enzyme I
disrupted showed increased acidification similar to that in the
wild-type strain. This indicates that the PTS is not involved in this
response whereas the regulatory function of 46-seryl phosphorylated HPr [HPr(Ser-P)] probably is involved. Protein analysis showed that the
production of both HPr and CcpA was induced severalfold (up to two- to
threefold) upon exposure to low temperatures. The las operon, which is subject to catabolite activation by the
CcpA-HPr(Ser-P) complex, was not induced upon cold shock, and no
increased lactate dehydrogenase (LDH) activity was observed. Similarly,
the rate-limiting enzyme of the glycolytic pathway under starvation
conditions, glyceraldehyde-3-phosphate dehydrogenase (GAPDH), was not
induced upon cold shock. This indicates that a factor other than LDH or GAPDH is rate determining for the increased glycolytic activity upon
exposure to low temperatures. Based on their cold induction and
involvement in cold adaptation of glycolysis, it is proposed that the
CcpA-HPr(Ser-P) control circuit regulates this factor(s) and hence
couples catabolite repression and cold shock response in a functional
and mechanistic way.
0099-2240/00/$04.00+0
Copyright © 2000, American Society for Microbiology. All rights reserved.
Changes in Glycolytic Activity of Lactococcus
lactis Induced by Low Temperature

*
Corresponding author. Mailing address: Laboratory of
Food Microbiology, Wageningen University, Bomenweg 2, 6703 HD
Wageningen, The Netherlands. Phone: 31-317-484981. Fax: 31-317-484893. E-mail: Tjakko.Abee{at}micro.fdsci.wau.nl.
Present address: Department of Genetics, Groningen Biomolecular
Sciences and Biotechnology Institute (GBB), University of Groningen,
9750 AA Haren, The Netherlands.
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