Understanding capsule production in Streptococcus thermophilus MR-1C

Principal Investigator:

Dr. Jeff Broadbent

Co-Investigators:

Dr. Dennis L. Welker

Project Summary:

Streptococcus thermophilus MR-1C enhances the functionality and yield of lowfat Mozzarella cheese. This effect is due to production of a capsular exopolysaccharide, and we have characterized several genes required for its synthesis. Since MR-1C does not have fast acid-producing ability, technology to make capsule-producing variants from fast acid-producing industrial S. thermophilus starters would benefit the US Mozzarella cheese industry. To reach this goal, we need to define the minimal genetic locus encoding capsule production in MR-1C. This project identified regions of the MR-1C cps cluster that are not present in the industrial, fast acid-producing, EPS-negative, Mozzarella cheese starter bacterium S. thermophilus TAO61.

Publications:

Broadbent, J. R., D. J. McMahon, D. Welker, C. J. Oberg, and S. Moineau. 2002. Biochemistry, genetics, and applications of exopolysaccharide production in Streptococcus thermophilus: a review. J. Dairy Sci. (accepted for publication).

Broadbent, J. R., D. J. McMahon, C. J. Oberg, and D. L. Welker. 2001. Use of exopolysaccharide-producing cultures to improve the functionality of low fat cheese. Int. Dairy J. 11:433-439.

Petersen, B. L., R. I. Dave, D. J. McMahon, C. J. Oberg, and J. R. Broadbent. 2000. Influence of capsular and ropy exopolysaccharide-producing Streptococcus thermophilus on Mozzarella cheese and cheese whey. J. Dairy Sci. 83:1952-1956.

Theses:

Petersen, B. L. 2001. Biochemistry and application of exopolysaccharide production in Mozzarella cheese starter cultures. MS thesis, Utah State University, Logan.

Published Abstract:

none

Presentations:

Welker, D. L., J. R. Broadbent, A. D. Cefalo, D. J. McMahon, and C. J. Oberg. 2002. Mechanism(s) for loss of exopolysaccharide synthesis phenotype in strains of Streptococcus thermophilus. Poster presentation at the 7th International Symposium of Lactic Acid Bacteria Genetics, Metabolism and Applications, Sept. 1-5, Egmond aan Zee, The Netherlands.

Welker, D. L., J. R. Broadbent, R. Jensen, D. J. McMahon, C. J. Oberg, and J. A. Ahlgren. 2002. Polymorphisms in closely related exopolysaccharide gene clusters of Streptococcus thermophilus may influence polymer type and composition. Poster presentation at the 7th International Symposium of Lactic Acid Bacteria Genetics, Metabolism and Applications, Sept. 1-5, Egmond aan Zee, The Netherlands.

Oberg, C.J., J.R. Broadbent, and D.J. McMahon. 2002. Applications of EPS production by lactic acid bacteria. Invited oral presentation for the symposium on exopolysaccharide production by lactic acid bacteria at the annual meeting of the American Dairy Science Association. July 21-25, Quebec City, Quebec, Canada.

Welker, D. L., C. J. Oberg, A. D. Cefalo, D. J. McMahon, and J. R. Broadbent. 2002. Insight on the mechanism(s) for loss of exopolysaccharide synthesis phenotype in Streptococcus thermophilus. Poster presentation at the 102nd general meeting of the American Society for Microbiology. May 19-23, Salt Lake City, UT.

Broadbent, J. R. 2001. Exopolysaccharide production in Streptococcus thermophilus: biochemistry, genetics, and applications. Invited oral presentation for Fifth Annual Symposium on Industrial and Fermentation Microbiology. April 27, University of Wisconsin, La Crosse.