Stable expression of the Lactobacillus casei bacteriophage A2 repressor blocks phage propagation during milk fermentation

• Published in: Journal of applied microbiology 1999-05, Vol.86 (5), p.812-816
• Main Authors: Alvarez, M. A., Rodríguez, A., Suárez, J. E.
• Format: Article
• Language: English
• Subjects: Animals; Bacteriophages - growth & development; Biological and medical sciences; Fermentation; Food industries; Food Microbiology; Fundamental and applied biological sciences. Psychology; Gene Expression; Lactobacillus casei; Lactobacillus casei - genetics; Lactobacillus casei - virology; Milk - microbiology; Milk and cheese industries. Ice creams; Phage phi a; Phenotype; Repressor Proteins - genetics
• ISSN: 1364-5072; 1365-2672
• DOI: 10.1046/j.1365-2672.1999.00728.x

A general strategy was applied to implement resistance against temperate bacteriophages that infect food fermentation starters through cloning and expression of the phage repressor. Lactobacillus casei ATCC 393 and phage A2 were used to demonstrate its feasibility as milk fermentation is drastically inhibited when the strain is infected by this phage. The engineered strain Lact. casei EM40::cI, which has the A2 repressor gene (cI) integrated into the genome, was completely resistant and able to ferment milk whether phage was present or not. In addition, viable phages were eliminated from the milk, probably through adsorption to the cell wall. Finally, the integration of cI in the genome resulted in a stable resistance phenotype, being unnecessary selective pressure during milk fermentation.