AEM
Home Help [Feedback] [For Subscribers] [Archive] [Search] [Contents]
This Article
Right arrow Full Text
Right arrow Full Text (PDF)
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Services
Right arrow Similar articles in this journal
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Right arrow Copyright Information
Right arrow Books from ASM Press
Right arrow MicrobeWorld
Citing Articles
Right arrow Citing Articles via HighWire
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Fernández, M.
Right arrow Articles by Kuipers, O. P.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Fernández, M.
Right arrow Articles by Kuipers, O. P.
Agricola
Right arrow Articles by Fernández, M.
Right arrow Articles by Kuipers, O. P.

Applied and Environmental Microbiology, January 2000, p. 42-48, Vol. 66, No. 1
0099-2240/0/$04.00+0
Copyright © 2000, American Society for Microbiology. All rights reserved.

Molecular and Functional Analyses of the metC Gene of Lactococcus lactis, Encoding Cystathionine beta -Lyase

María Fernández,1 Wim van Doesburg,1 Ger A. M. Rutten,1 Joey D. Marugg,1,dagger Arno C. Alting,1 Richard van Kranenburg,1,2,* and Oscar P. Kuipers1,2,Dagger

Microbial Ingredients Section, NIZO food research, Ede,1 and Wageningen Centre for Food Sciences, Wageningen,2 The Netherlands

Received 6 July 1999/Accepted 12 October 1999

The enzymatic degradation of amino acids in cheese is believed to generate aroma compounds and therefore to be essential for flavor development. Cystathionine beta -lyase (CBL) can convert cystathionine to homocysteine but is also able to catalyze an alpha ,gamma elimination. With methionine as a substrate, it produces volatile sulfur compounds which are important for flavor formation in Gouda cheese. The metC gene, which encodes CBL, was cloned from the Lactococcus lactis model strain MG1363 and from strain B78, isolated from a cheese starter culture and known to have a high capacity to produce volatile compounds. The metC gene was found to be cotranscribed with a downstream cysK gene, which encodes a putative cysteine synthase. The MetC proteins of both strains were overproduced in strain MG1363 with the NICE (nisin-controlled expression) system, resulting in a >25-fold increase in cystathionine lyase activity. A disruption of the metC gene was achieved in strain MG1363. Determination of enzymatic activities in the overproducing and knockout strains revealed that MetC is essential for the degradation of cystathionine but that at least one lyase other than CBL contributes to methionine degradation via alpha ,gamma elimination to form volatile aroma compounds.


* Corresponding author. Mailing address: NIZO food research, P.O. Box 20, 6710 BA Ede, The Netherlands. Phone: 31-318-659511. Fax: 31-318-650400. E-mail: kranenbu{at}nizo.nl.

dagger Present address: Nestlé Research Center, Vers-chez-les-Blanc, CH-1000 Lausanne 26, Switzerland.

Dagger Present address: Dept. of Genetics, University of Groningen, Haren, The Netherlands.


Applied and Environmental Microbiology, January 2000, p. 42-48, Vol. 66, No. 1
0099-2240/0/$04.00+0
Copyright © 2000, American Society for Microbiology. All rights reserved.



This article has been cited by other articles:




Home Help [Feedback] [For Subscribers] [Archive] [Search] [Contents]
J. Bacteriol. Microbiol. Mol. Biol. Rev. Eukaryot. Cell All ASM Journals

Copyright © 2000 by the American Society for Microbiology. All rights reserved.