Application of a Metablic Control Switch to Improve and Control Starter Proteolysis in Mozzarella Cheese

Principal Investigator:

Dr. Jeffery R. Broadbent, Utah State University

Co-Investigators:

Dr. Donald J. McMahon, Utah State University
Dr. Craig Oberg, Weber State University

Project Summary:

The purpose of this project is to develop an expression system for important dairy starter cultures that will allow these bacteria to produce high levels of a desired protein during a specific (and transient) stage of cheese manufacture. Although such an expression system would have application in several dairy processes, research outlined in this proposal will focus on its use to avoid pitfalls presently associated with the addition of proteolytic enzymes to cheese. To accomplish this, we will investigate: (1) regulation of a tightly regulated Lactobacillus helveticus heat shock gene promoter; (2) application of this promoter in a gene expression system that can transiently induce enzyme production during the cook step in cheese manufacture and; (3) this system's performance in cheese using a model enzyme such as the Bacillus subtilus neutral protease. These experiments will allow us to determine whether a natural metabolic switch can be employed to avoid problems presently associated with the addition of proteolytic enzymes to cheese. Results from this work will provide basic and applied information needed by industry to control and accelerate functionality in Mozzarella cheese.

Publications:

Broadbent, J.R., B. Rodriguez, C.J. Oberg, and D.J. McMahon. 2001. Temperature-inducible expression of the Bacillus subtilis neutral proteinase in lactic acid bacteria. In preparation.

Oberg, C.J., J.R. Broadbent, and D.J. McMahon. 1998. Developments in thermophilic starter cultures for cheese. Aust. J. Dairy Technol. 53:102-104.

Broadbent, J.R., C.J. Oberg, and L. Wei. 1998. Characterization of the Lactobacillus helveticus groESL operon. Res. Microbiol. 149:247-253.

Theses:

None

Published Abstract:

Broadbent, J.R., L. Wei, D. J. McMahon, and C.J. Oberg. 1998. Characterization of the Lactobacillus helveticus groESL operon. J. Dairy Sci. 81(Suppl. 1):5.

Presentations:

Broadbent, J.R., L. Wei, D.J. McMahon, and C.J. Oberg. Characterization of the Lactobacillus helveticus groESL operon. Poster presentation at the Ann. Mtg. Amer. Dairy Sci. Assoc. July 27-30, Denver, CO.

Oberg, C.J., J.R. Broadbent, and D.J. McMahon. 1998. Developments in thermophilic starter cultures for cheese. Cheese Science '98, July 1-3, Melbourne, Australia.