Abstract
BackgroundStreptococcus 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.ResultsIn this study, we demonstrated that Streptococcus thermophilus thermal stress adaptation required the rgg0182 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 Rgg0182 is a transcriptional regulator controlling the expression of its neighboring genes as well as chaperones and proteases encoding genes. Therefore, analysis of a Δrgg0182 mutant revealed that this protein played a role in the heat shock adaptation of Streptococcus thermophilus LMG18311.ConclusionsThese data showed the importance of the Rgg0182 transcriptional regulator on the survival of S. thermophilus during dairy processes and more specifically during changes in temperature.
Highlights
Streptococcus thermophilus is an important starter strain for the production of yogurt and cheeses
We demonstrate that (i) the transcription of rgg0182 gene from S. thermophilus LMG18311 is influenced by culture medium and growth temperature, (ii) Rgg0182 is a transcriptional regulator that modulate the transcription of its proximal target genes but is involved in the network of regulation of the transcription of genes coding chaperones and proteases, (iii) this gene is involved in heat shock response
The rgg0182 gene (864 bp) potentially encodes a protein of 288 amino acids with a predicted molecular mass of 35.6 kDa. This protein exhibited an identity of about 30% with other streptococcal proteins belonging to the Rgg family of transcriptional regulators and 35% identity (e-value = 8e-48) with Rgg1358 from S. thermophilus LMD-9 which was recently shown to be involved in a quorum sensing (QS) mechanism [9]
Summary
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. The species Streptococcus thermophilus is a Lactic Acid Bacterium (LAB) used as a starter of fermentation in yogurt and cheese production. During the production of dairy products, temperature shifts are applied to regulate the bacterial growth and, control the lactic acid production [1]. S. thermophilus survival against thermal stress is known about the network of regulation controlling S. thermophilus adaptation to temperature changes
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