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Applied and Environmental Microbiology, November 2005, p. 7414-7425, Vol. 71, No. 11
0099-2240/05/$08.00+0     doi:10.1128/AEM.71.11.7414-7425.2005
Copyright © 2005, American Society for Microbiology. All Rights Reserved.

Identification and Molecular Characterization of the Chromosomal Exopolysaccharide Biosynthesis Gene Cluster from Lactococcus lactis subsp. cremoris SMQ-461

N. Dabour1,2 and G. LaPointe1*

STELA Dairy Research Centre and Institute for Nutraceuticals and Functional Foods, Université Laval, Québec, QC, Canada G1K 7P4,1 Department of Dairy Science and Technology, Faculty of Agriculture, University of Alexandria, Alexandria, Egypt2

Received 9 March 2005/ Accepted 20 July 2005

The exopolysaccharide (EPS) capsule-forming strain SMQ-461 of Lactococcus lactis subsp. cremoris, isolated from raw milk, produces EPS with an apparent molecular mass of >1.6 x 106 Da. The EPS biosynthetic genes are located on the chromosome in a 13.2-kb region consisting of 15 open reading frames. This region is flanked by three IS1077-related tnp genes (L. lactis) at the 5' end and orfY, along with an IS981-related tnp gene, at the 3' end. The eps genes are organized in specific regions involved in regulation, chain length determination, biosynthesis of the repeat unit, polymerization, and export. Three (epsGIK) of the six predicted glycosyltransferase gene products showed low amino acid similarity with known glycosyltransferases. The structure of the repeat unit could thus be different from those known to date for Lactococcus. Reverse transcription-PCR analysis revealed that the eps locus is transcribed as a single mRNA. The function of the eps gene cluster was confirmed by disrupting the priming glycosyltransferase gene (epsD) in Lactococcus cremoris SMQ-461, generating non-EPS-producing reversible mutants. This is the first report of a chromosomal location for EPS genetic elements in Lactococcus cremoris, with novel glycosyltransferases not encountered before in lactic acid bacteria.

* Corresponding author. Mailing address: STELA Dairy Research Centre, Room 1316, Pavillon Paul-Comtois, Université Laval, Québec, QC, Canada G1K 7P4. Phone: (418) 656-2131, ext. 3100. Fax: (418) 656-3353. E-mail: gisele.lapointe{at}fsaa.ulaval.ca.

Applied and Environmental Microbiology, November 2005, p. 7414-7425, Vol. 71, No. 11
0099-2240/05/$08.00+0     doi:10.1128/AEM.71.11.7414-7425.2005
Copyright © 2005, American Society for Microbiology. All Rights Reserved.



This article has been cited by other articles:

  • Wegmann, U., O'Connell-Motherway, M., Zomer, A., Buist, G., Shearman, C., Canchaya, C., Ventura, M., Goesmann, A., Gasson, M. J., Kuipers, O. P., van Sinderen, D., Kok, J. (2007). Complete Genome Sequence of the Prototype Lactic Acid Bacterium Lactococcus lactis subsp. cremoris MG1363. J. Bacteriol. 189: 3256-3270 [Abstract] [Full Text]  


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