Effect of high temperature on viability of Lactobacillus casei and analysis of secreted and GroEL proteins profiles

The bacterial heat shock response is characterized by the elevated expression of a number of chaperone complexes including the GroEL and the rate change of synthesis of certain proteins (total and secreted). In this work, after incubation at 45°C, total and secreted proteins profiles of stressed bacteria were found to be altered when analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). In addition, the level expression of GroEL was evaluated with Western blot. Our results show a marked increase in both GroEL expression and protein synthesis at 45°C. These modifications were manifested by the appearance and/or disappearance of bands as well as in the level of expression of certain proteins.   Key words: Lactobacillus casei, heat shock, GroEL, secreted and total proteins, sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), Western blotting.