The rgg0182 gene encodes a transcriptional regulator required for the full Streptococcus thermophilus LMG18311 thermal adaptation

Background: Streptococcus thermophilus is an important starter strain for the production of yogurt and cheeses. The analysis of sequenced genomes of four strains of S. thermophilus indicates that they contain several genes of the rgg familly potentially encoding transcriptional regulators. Some of the Rgg proteins are known to be involved in bacterial stress adaptation. Results: In this study, we demonstrated that Streptococcus thermophilus thermal stress adaptation required the rgg(0182) gene which transcription depends on the culture medium and the growth temperature. This gene encoded a protein showing similarity with members of the Rgg family transcriptional regulator. Our data confirmed that Rgg(0182) is a transcriptional regulator controlling the expression of its neighboring genes as well as chaperones and proteases encoding genes. Therefore, analysis of a Delta rgg(0182) mutant revealed that this protein played a role in the heat shock adaptation of Streptococcus thermophilus LMG18311. Conclusions: These data showed the importance of the Rgg(0182) transcriptional regulator on the survival of S. thermophilus during dairy processes and more specifically during changes in temperature.