Heat Acclimation of Bifidobacterium longum and Proteomic Changes Behind It.

Bifidobacterium is an important probiotic bacterium and extensively applied to functional food. Its survival is strongly affected by the heat-shock process during manufacture. Acclimation is thought to be able to enhance Bifidobacterium's resistance to heat stress; however, so far little is known about the protein expression changes underlying the adaptation process. In this study, the appropriate acclimation temperature for Bifidobacterium longum was determined as 43 °C, and 2-dimensional gel electrophoresis-based proteomic analysis was performed to reveal the protein changes in expression levels behind heat acclimation. Twenty proteins displayed significantly expression changes after heat acclimation, including general stress response proteins, metabolic enzymes, components of ABC transporters, transcriptional regulators, and hypothetical proteins. Two important chaperones GroEL and IbpA were found to be induced during heat acclimation, implying that they might play key roles in the heat resistance of acclimation. Although many further studies are needed to explore the complex mechanisms, this study enhances the understanding of protein changes underlying the heat acclimation of Bifidobacterium and provides important molecular clues for its future research.